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The effect of progressive muscle relaxation in the basal cortisol response of high and low neurocitism students

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(1)DOCTORAL THESIS 2014. THE EFFECT OF PROGRESSIVE MUSCLE RELAXATION IN THE BASAL CORTISOL RESPONSE OF HIGH AND LOW NEUROTICISM STUDENTS. Karin Chellew Gâlvez.

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(3) Universität de les Ules Balears DOCTORAL THESIS 2014 Doctoral Programme of Cognition and Human Evolution. THE EFFECT OF PROGRESSIVE MUSCLE RELAXATION IN THE BASAL CORTISOL RESPONSE OF HIGH AND LOW NEUROTICISM STUDENTS. Karin Chellew Gâlvez. Director: Gloria Garcia de la Banda Co-director: Phil Evans Ponent: Enric Munar Roca Doctor by the Universitat de les Illes Balears.

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(5) To my parents,. and to my godparents,. Tito and Lily. Olivia and. Roberto.

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(7) "We have negative mental habits that come up over and over again. One of the most significant negative habits we should be aware of is that of constantly allowing our mind to run off into the future. Perhaps we got this from our parents. Carried away by our worries, we're unable to live fully and happily in the present. Deep down, we believe we can't really be happy just yet—that we still have a few more boxes to be checked off before we can really enjoy life. We speculate, dream, strategize, and plan for these "conditions of happiness" we want to have in the future; and we continually chase after that future, even while we sleep. We may have fears about the future because we don't know how it's going to turn out and these worries and anxieties keep us from enjoying being here now." Thich Nhat Hanh Peace is every breath: A practice for our busy lives (2012, p. 23).

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(9) Acknowledgements. Infinitive thanks: T o my w h o l e family w h o is always there to support m e and gives me the w i n g s to pursue my goals and help m e to carry on all these y e a r s . always been easy.. I know that it has not. To my girls, Vicky, Malen, Julia F. C., Natalia, Julia U., and. Emnita, for always being there w h e n I needed it the m o s t ! T o my very good friends from IFISC, specially to: Pedrito, Enrico, Miguel, and P r z e m e k for all those great times that w e. shared this. last two. years. at. lunch, rutas. martianas,. "fiestas. multiculturales",. outings, paintballs, etc., that gave m e the strength and motivated me. to carry on. G u y s , Y O U R O C K ! T o María Saletas w h o always w a s there to help me. T o Diego, w h o always m a d e m e laugh and m a d e my day a little bit less stressful at the bar. T o my colleagues, good friends, and my s e c o n d family: Vicky, Jacobo, P e p , Malen, and S e l e n e for all these years of hard w o r k at the office, travels, breakfasts, etc. Guys you are the best, thank you for all the g o o d experiences! T o Esperanga, thank you for all those m o m e n t s that w e shared, at breakfast, travelling by car, conversations, etc., they w e r e very special to me.. T o all the extraordinary people. and professors that I had the pleasure to meet in so m a n y places all these years, thank y o u for all that I learned from y o u ! T o y o u Przemek, y o u have m a d e my last years a very special time. T o Phil Evans, thank you to be part of this process and thank you to share all your knowledge and time with me. Finally, to Gloria, since the m o m e n t I met you, y o u have b e e n an inspiration and a role model for me. I have no w o r d s to express my gratitude to you for always being there for me, to share all your knowledge, time and dedication..

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(11) Agradecimientos. Gracias infinitas: A toda mi familia que siempre está allí para a p o y a r m e y d a r m e las alas para perseguir mis objetivos y a y u d a r m e a continuar durante todos estos años.. Sé que. no siempre ha sido fácil. A mis chicas: Vicky, Malen, Julia F. C., Natalia, Julia U. y Emnita por estar siempre allí cuando m á s las he necesitado.. A mis m u y buenos. amigos del IFISC, especialmente a: Pedrito, Enrico, Miguel y P r z e m e k por todos esos buenos m o m e n t o s que h e m o s compartido estos últimos años en las comidas, rutas. martianas,. fiestas multiculturales, excursiones, paintballs, etc., que m e han. d a d o la fuerza y me han motivado a seguir. quien siempre ha estado allí para a y u d a r m e .. Chicos, Y O U R O C K ! A María Saletas, A Diego, que siempre m e hizo reír y. hacer mi día un poco m e n o s estresante en el bar. A mis colegas, buenos amigos y mi s e g u n d a familia: Vicky, Jacobo, Pep, Malen y Selene por todos estos años de arduo trabajo en el despacho, viajes, desayunos, etc. Chicos sois lo mejor, gracias por todas las buenas experiencias! A Esperanga, gracias por todos esos m o m e n t o s que h e m o s compartido, en los desayunos, viajando en el coche, conversaciones, etc. han sido m u y especiales para mí.. A todas las extraordinarias personas y. profesores que he tenido el placer de conocer en tantos sitios todos estos años, gracias por todo lo que he aprendido de vosotros! A ti Przemek, has hecho de mis últimos años un tiempo m u y especial.. A Phil Evans, gracias por formar parte de. este proceso, gracias por compartir tu conocimiento y tiempo conmigo.. Finalmente. a Gloria, desde que te conocí has sido una inspiración y un modelo a seguir.. No. tengo palabras para expresar mi gratitud por estar siempre allí para mí,. por. compartir tu conocimiento, tiempo y dedicación..

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(13) Table of contents Preface Resum Resumen Abstract. 15 17 19 21. Chapter 1 Introduction and theoretical framework 1. 2. 3. 4.. 5. 6.. Introduction Personality 2 . 1 . Neuroticism Stress Cortisol 4 . 1 . Daytime Cortisol circadian cycle 4 . 1 . 1 . Cortisol awakening cortisol (CAR) 4.1.2. Area under the curve (AUC) 4.2. Cortisol Reactivity Personality and cortisol: relation between concepts A P M R as an intervention to reduce stress. 25 27 29 31 35 37 37 40 43 47 51. Chapter 2 Study 1 : Cortisol response under a stressful situation: Public speaking 1. 2. 3. 4. 5.. Introduction Aim Method Results Discussion. 57 58 58 61 65. Chapter 3 Study 2: Cortisol secretion under daily situations in participants with extreme scores on neuroticism 1. 2. 3. 4. 5.. Introduction Aim Method Results Discussion. 69 71 71 79 85. Chapter 4 Study 3: Abbreviated Progressive Muscle Relaxation to reduce psychological and physiological stress 1. Introduction 2. A i m 3. Method 4. Results. 89 92 92 100.

(14) 5.. 104. Chapter 5 Discussion, conclusions and future lines of research 1. General discussion 2. Limitations 3. Conclusion 3 . 1 . Future lines of research References. 109 117 119 121 123. Appendix 1. 2. 3. 4. 5. 6. 7.. Personality questionnaires Rating scales MEMS CAPS AARDEX Saliva collection device Centrifuge for saliva samples Salivary sampling protocol. 149 153 155 156 157 158 159.

(15) PREFACE T h e aim of the present PhD dissertation is to assess how personality traits influence. the. cortisol. response. of. undergraduate. conditions; stressful, baseline, and relaxation. cortisol. response facing. undergraduate students.. a. stressful. situation. students. in. three. different. This w o r k starts evaluating the (public. speaking). of. psychology. T h e n continues with the study of daily cortisol (baseline. cortisol) in students with extreme scores in Neuroticism (N). Finally, this dissertation ends with the evaluation of the efficacy of abbreviate progressive muscle relaxation (APMR), to reduce overall levels of both psychological and physiological stress in undergraduate students scoring high and low in N.. T h e s e three studies have. resulted in two publications:. •. García-Banda, G., Servera, M., Chellew, K., Meisel, V., Fornes, J., Cardo, E., Perez, G., Riesco, M., & Doctor, R. M. (2011). Prosocial personality traits and adaptation to stress. Social Behavior. & Personality,. 39(10), 1337-1348. doi:. 10.2224/sbp.2011.39.10.1337. •. García-Banda, G., Chellew, K., Fornes, J., Perez, G., Servera, M., & Evans, P. (2014). Neuroticism and cortisol: Pinning d o w n an expected effect. International. Journal. of Psychopathology,. 91, 132-138. doi:. 10.1016/j.ijpsycho.2013.12.05 A n d , a future publication, w h i c h manuscript has been recently submitted:. •. Chellew, K., Evans, P., Fornes, J., Perez, G., & García-Banda, G. (Submitted). T h e effect of progressive muscle relaxation on daily cortisol secretion. International. Journal. of Stress. Management..

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(17) RESUM. Els trets individuals. en. de. personalitat j u g u e n. la secreció. del. un. Cortisol.. No. paper. rellevant. obstant. això,. en. les. diferencies. la naturalesa. i els. m e c a n i s m e s subjacents d'aquesta relació tot i r o m a n e n poc clars. El Cortisol, producte final de l'eix Hipotàlem-pituìtari-Adrenal (HPA), és un glucocorticoide que el nostre cos secreta naturalment seguint un pronunciat cicle diürn, a m b nivells elevats davant de situacions particularment estressants (reactivitat del cortisol). La present tesi doctoral té com a objectiu elucidar com els trets de personalitat influeixen en la resposta. del. cortisol. d'estudiants. universitaris. en. tres. condicions. diferents:. estressant, basal i de relaxació. A q u e s t treball c o m e n g a avaluant la resposta del cortisol. davant. psicologia. relacionada. d'una. Esperàvem amb. situació que. Obertura,. estressant la. (parlar. reactivitat. Amabilitat. i. del. en. public). cortisol. Responsabilitat,. en. estigués. estudiants. de. positivament. i negativament. amb. Extraversió, Neuroticisme i Psicoticisme. En el nostre segon estudi, avaluem el perfil de secreció de cortisol basal en estudiants universitaris a m b puntuacions extremes en Neuroticisme (N) tractant de demostrar una associació teòrica esperat entre N i la secreció de cortisol diürn. P e n s à v e m que participants a m b puntuacions altes en N exhibirien constantment nivells elevats de cortisol diürn basal comparat a m b aquells a m b puntuacions baixes en N. Finalment, volíem examinar si una setmana de Relaxació Muscular Progressiva Abreujada ( A P M R ) era eficag per reduir nivells totals d'estrès psicològic i fisiològic de participants a m b puntuacions extremes en N. Els nostres resultats confirmen, en primer lloc, que parlar en public a u g m e n t a significativament la secreció de cortisol en comparació a m b una activitat a c a d è m i c a.

(18) no estressant. A m é s a més, Responsabilitat ha estât associada a m b un a u g m e n t significatiu dels nivells de Cortisol, i Psicoticisme a m b una a la baixa. En s e g o n lloc, trobem que Neuroticisme ha estat associat a m b una elevada secreció de cortisol davant de situacions d'estrès diari, encara que n o m é s després dels primers 45 min. després de despertar (CAR). A q u e s t a associació ha estat independent del genere i edat dels participants, si f u m a v e n o no, l'hora de despertar, o del dia de l'estudi. Finalment, en tercer lloc, A P M R és una eina eficaç per disminuir tant. l'estrès. psicológic com fisiológic en tots els participants, independentment de puntuacions altes o baixes en Neuroticisme, el gènere, o l'edat dels participants..

(19) RESUMEN. Los rasgos de personalidad j u e g a n un papel relevante en las diferencias individuales. en. la. secreción. del. cortisol.. Sin. embargo,. la. naturaleza. y. los. m e c a n i s m o s subyacentes a esta relación aún p e r m a n e c e n poco claros. El cortisol, producto final del eje Hipotálamo-Pituitario-Adrenal (HPA), es un glucocorticoide que nuestro cuerpo secreta naturalmente de acuerdo a un ciclo diurno pronunciado, con niveles elevados ante situaciones estresantes (reactividad del cortisol). El objetivo de la presente tesis doctoral ha sido elucidar c ó m o los rasgos de personalidad influyen en la respuesta del cortisol de estudiantes universitarios en tres condiciones distintas: estresante, basal y de relajación. Este trabajo comienza evaluando la respuesta. del. cortisol. ante. una. situación. estresante. (hablar. en. público). en. estudiantes de psicología. E s p e r á b a m o s que la reactividad del cortisol estuviera positivamente. relacionada. con. Apertura,. Amabilidad. y. Responsabilidad,. y. negativamente con Extraversión, Neuroticismo y Psicoticismo. En nuestro segundo estudio,. evaluamos. universitarios. con. el. perfil. de. secreción. de. puntuaciones. extremas. en. cortisol. basal. Neuroticismo. en (N).. estudiantes Con. ello. pretendíamos demostrar de f o r m a experimental una asociación planteada a nivel teórico entre N y secreción de cortisol diurno. A s í e s p e r á b a m o s que los participantes con puntuaciones altas en N exhibieran niveles elevados de cortisol diurno basal c o m p a r a d o con participantes con puntuaciones bajas en este rasgo. Por último, queríamos examinar si una s e m a n a de Relajación Muscular Progresiva A b r e v i a d a ( A P M R ) era efectiva en reducir los niveles totales de estrés psicológico y fisiológico de participantes con puntuaciones extremas en N. Nuestros resultados confirman,.

(20) en primer lugar, que hablar en público a u m e n t a significativamente la secreción de cortisol en c o m p a r a c i ó n con una actividad a c a d é m i c a no estresante.. Además,. Responsabilidad se asoció con un aumento significativo de la respuesta de cortisol, y Psicoticismo con una respuesta a la baja. En s e g u n d o lugar, encontramos que altos niveles de Neuroticismo se asociaron con una secreción elevada de cortisol en situaciones de estrés diario, a u n q u e solo después de los primeros 45 min después de despertar (CAR). Esta asociación fue independiente del género y edad de los participantes, si f u m a b a n o no, de la hora de despertar, o del día del estudio. Por último, en tercer lugar, A P M R fue eficaz en disminuir tanto el estrés psicológico c o m o fisiológico en todos los participantes, independientemente del género, la edad o. de. la. puntuación. de. Neuroticismo. de. los. participantes..

(21) ABSTRACT. Personality traits play a significant role in individual differences in Cortisol response (LeBlanc,. Ducharme, & T h o m p s o n , 2004). However,. the nature. and. underlying m e c h a n i s m s of the relationship between cortisol secretion and personality traits still remain unclear. Cortisol, an end product of the Hypothalamic-PituitaryAdrenal axis (HPA), is a glucocorticoid that our body naturally secretes according to a pronounced diurnal cycle with increased values under stressful situations (cortisol reactivity). T h e aim of the present PhD dissertation w a s to elucidate how personality traits influence the cortisol secretion of undergraduate students in three different conditions; stressful, baseline, and relaxation. This w o r k began by evaluating the cortisol. response facing. students.. We. believed. a that. stressful cortisol. situation reactivity. (public would. speaking) be. of. positively. psychology related. to. Openness, Agreeableness, and Conscientiousness, and negatively to Extraversion, Neuroticism and Psychoticism. In our second study, w e a s s e s s e d the baseline cortisol in students with extreme scores in Neuroticism (N) attempting to prove a theoretical expected association between. N and diurnal cortisol secretion.. We. postulated that high N participants w o u l d display elevated diurnal background levels of cortisol c o m p a r e d to low N participants. Finally, w e e x a m i n e d whether one w e e k of Abbreviated Progressive Muscle Relaxation ( A P M R ) w a s effective in reducing overall. levels. of. psychological. and. physiological. stress. of. high-. and. low-N. participants. Our results confirmed, firstly, that public speaking significantly increased cortisol secretion w h e n c o m p a r e d to a non-stressful academic activity. In addition, Conscientiousness w a s associated with an e n h a n c e d cortisol response to public.

(22) speaking, and Psychoticism with a blunted one. Secondly, w e found that high levels of Neuroticism w e r e associated with elevated cortisol secretion on daily stress, but only after the first 45. min following. awakening. (CAR). This. association. was. independent of sex and age, s m o k i n g status, awakening time, and day of study. Finally, in third place, A P M R w a s effective in decreasing both psychological and physiological stress in all participants independently of their N-score, gender, or age..

(23) Chapter 1. Introduction and theoretical framework.

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(25) 1.. Introduction. Traditionally, aberrant cortisol dynamics and personality traits have closely linked to m o o d and anxiety disorders (Oswald et al., 2006).. been. Evidence. suggests that personality traits m a y play a significant role in individual differences in cortisol response (LeBlanc, Ducharme, & T h o m p s o n , 2004).. However, the nature. and the underlying m e c h a n i s m s of the relation between cortisol secretion personality. traits. still. remain. unclear.. Cortisol, the. HPA. end. product,. and is. a. glucocorticoid that our body naturally secretes according to a pronounced diurnal cycle with increased values under particularly stressful conditions (cortisol reactivity). In this thesis, cortisol responses to public speaking w e r e e x a m i n e d to test the hypotheses that reactivity w o u l d be positively related with openness, agreeableness, and. conscientiousness,. psychoticism.. and. negatively. to. extraversion,. neuroticism. and. Moreover, there are strong theoretical arguments that those high on. neuroticism (N) should normally exhibit higher prevailing levels of the stress-linked hormone cortisol.. Thus, in the second study presented in this thesis w e tried to. prove expected associations between N and diurnal cortisol secretion. W e had one simple but clear theoretically derived formal hypothesis, that high N participants w o u l d constantly display elevated diurnal background levels of cortisol c o m p a r e d to low N participants. Finally, w e w a n t e d to examine whether an intervention consisting of o n e - w e e k of Abbreviate Progressive Muscle Relaxation ( A P M R ) w a s effective in reducing overall levels of both psychological and physiological stress of high- and low-N participants. In this chapter w e present a description of the main concepts used along this thesis. that. include: personality,. neuroticism,. stress,. cortisol,. daytime. cortisol.

(26) circadian cycle (CAR and A U C ) , cortisol reactivity, and Abbreviated Muscle Relaxation (APMR).. Progressive. In the second chapter, w e will introduce the three. studies that form part of this thesis, and finally, in the last chapter w e discuss and highlight the main results and limitations of these studies, reach conclusions, and suggest future lines of research that arise from this work..

(27) 2.. Personality. Eysenck (1970) defined personality as: "A more or less stable organization. of a person's. determines person's. his unique more. temperament,. adjustment. or less his more. (emotion);. intellect,. behaviour. (intelligence);. bodily configuration. character,. his. stable. and. temperament,. to the environment. enduring. or less stable more. or less. physique,. and enduring stable. his more. and neuroendocrine. system. and or less. endowment". intellect, Where. and. and physique, character. of conative. of affective. enduring. system. which. denotes. behaviour. system. stable. enduring. a. (will); behaviour. of. and enduring. cognitive system. (p. 243).. In this thesis w e f o c u s e d on the Eysenck's t e m p e r a m e n t aspect of personality that refers to intrapersonal processes (cognitive, emotional, and motivational) that determine our individual behaviour.. More specifically, personality can be described. as consistent behaviour patterns, stable across time and consistent across situations and can be quantitatively assessed (Burger, 2011). P a u n o n e n (1998) pointed out that there is s o m e intuitive appeal to the conceptualization that factors of personality are organized hierarchically, arranged according to the breadth of the behaviour d o m a i n s represented (see Figure 1). There are several approaches that have a hierarchical structure to describe, explain, and assess personality traits.. In the present thesis w e are going to present two of. the most used and well-known models: the Eysenck's biosocial approach (Eysenck & Eysenck, 1969; Eysenck & Eysenck, 1985a) and the psycholexical approach of the Five-Factor Model (FFM; Costa & McCrae, 1985)..

(28) Figure. 1.. Representation of a hierarchical model of. organization. A d a p t e d from "Hierarchical and prediction Personality. of behavior,". organization. personality. of. personality. by S. V. Paunonen, 1998, Journal. and Social Psychology,. of. 74(2), p. 539. Copyright 1998 by. the A m e r i c a n Psychological Association, Inc.. In. both. approaches. neuroticism and extraversion.. two. basic. personality. traits. are. acknowledged,. People with high scores in emotional instability or. 'neuroticism' dimension are moody, touchy and anxious, w h e r e a s those with low scores. are relaxed, even t e m p e r e d. and calm.. People with. extraversion are enthusiastic, sociable, talkative and optimistic.. high scores. in. On the contrary,. introverts are reserved, pessimistic and keep themselves to themselves.. Eysenck. proposed a third dimension called psychoticism, reflecting impulsive, antisocial, aggressive,. cold,. egocentric,. lack. of. empathy,. behaviours (Eysenck, 1 9 9 1 , 1992a, 1992b).. creative,. and. tough-minded. In the FFM of Costa and McCrae. (1985) three more fundamental traits w e r e included: openness, agreeableness, and conscientiousness.. O p e n n e s s involves active imagination, aesthetic sensitivity,. attentiveness to inner feelings, preference for variety, and intellectual curiosity. Characteristics s u c h as trust, straightforwardness, altruism, compliance, modesty,.

(29) and tender-mindedness are c o m p o n e n t s of agreeableness.. Qualities of order,. dutifulness, achievement striving, self-discipline, and deliberation are characteristics of conscientiousness (Costa, McCrae, & Dye, 1 9 9 1 ; Costa and McCrae, 1992b).. 2.1.. Neuroticism. T h e personality trait of neuroticism (N) refers to relatively stable tendencies to respond with negative emotions to threat, frustration, or loss (Costa & McCrae, 1992a).. Individuals in the general population vary noticeably on this trait, ranging. from frequent and intense emotional reactions to minor challenges to almost non¬ emotional response even if they are facing significant difficulties (Lahey, 2009). N is operationally defined by items referring to irritability, anger, sadness, anxiety, worry, hostility,. self-consciousness,. and. vulnerability,. which. have. been f o u n d. to. be. substantially correlated with one another in factor analyses (Costa & McCrae, 1992a).. People w h o score low in N, contrary to people high in N, tend to be more. calmed and confident, and appear to cope better with stress.. N is believed to reflect a stable disposition involving specific biological and psychological m e c h a n i s m s that produce its robust association with psychopathology. In fact, N has been s h o w n prospectively to predict the development of emotional disorders. including. major. depression,. posttraumatic-stress. disorder. (PTSD),. phobias, and panic attacks (e.g., Breslau, Davis, & Andreski, 1995; Clark, W a t s o n , & Mineka, 1994; Hayward, Killen, Kraemer, & Taylor, 2 0 0 0 ; Krueger, Caspi, Moffitt, Silva, & M c G e e , 1996).. In addition, females N scores have been s h o w n to be. slightly but significantly higher than in males (Costa, Terracciano, & McCrae, 2001),.

(30) w h i c h could explain w h y w e f o u n d more w o m e n developing these type of disorders than m e n .. O n e essential aspect of neuroticism is that it involves individual differences in cognition and information processing, producing biases, specifically, under stressful situations.. In fact, high-N individuals, c o m p a r e d with low-N ones, show heightened. attention to negative or threatening information (rather than neutral information), as evidenced by a faster response to and a slower detachment from negative or threatening stimuli (Ormel et al., 2013).. Such negative responses to challenges are. both frequent and out of proportion to the circumstances for individuals w h o are high in this trait (McCrae & Costa, 2003).. Therefore in our last two studies w e included. extreme N-scores participants (high vs. low) in order to observe better differences between these t w o groups.. In the next section, w e will introduce the concept of stress and its definition, the main stress sources (stressors) that could affect us. This include the description of major life events and hassles, and finally how w e can measure t h e m ..

(31) 3.. Stress. Stress occurs w h e n environmental d e m a n d s overwhelm one's abilities to meet those d e m a n d s (Lazarus & Folkman, 1984) and is an influential construct in health research (Keller et al., 2012).. T h e interactionist model of stress (Lazarus &. Folkman, 1984; Mischel, 2009) suggests a bidirectional relationship between an individual's response and a stressful situation.. T h e recent development of this. model (Conger & Donnellan, 2007) differentiates between stress causation (stress, such. as. life. events,. may. lead. to. a. change. in. an. individual's. personality. characteristics that in turn affects their response to stressful events) and stress selection (one or more individual personality characteristics may increase the degree to w h i c h a life event is experienced as stressful).. In this study w e f o c u s e d in the. latest one. There are several sources of stress that can interfere in our lives: chronic stress, acute stress and daily stress (APA, 2014).. Chronic stress refers to the. constant and persisting stress stimuli over an extended period of time that can lead to. psychological. conditions.. and. physical. debilitation. and. it can. result. in serious. health. A c u t e stress is the most c o m m o n form of stress a m o n g h u m a n s and,. contrary to chronic stress, it refers to particular short-term stressful situations (e.g., an e x a m , an interview) that produces an acute stress response, but that decreases or disappears after the stressor is no longer available.. Finally, another c o m m o n. source of stress is daily stress, w h i c h refers to minor stressful events s u c h as, daily a n n o y a n c e s and hassles (e.g., making decisions, meeting deadline at w o r k or university, traffic j a m s , etc.) that are present in everybody's life.. W h a t is relevant. about this type of stress is that continue exposure to them can generate as m u c h.

(32) d a m a g e in the long-term than chronic stress.. In this thesis w e focus on acute and. daily stress because w e considered that both stressors are part of the student's life. W e did not include chronic stress because it w o u l d needs a longitudinal study design and w h a t w a s out of our study scope. In relation to acute stress, w e believe that undergraduate students. have. frequently to face several a c a d e m i c stressors (e.g., a c a d e m i c exams, written assays, public speaking, etc.), that generate an acute stress response.. Public speaking has. been proved to be a potent social stimuli widely used in stress research (Schoofs, Hartmann, & Wolf, 2008).. Specifically, this task involves social evaluation by peers. (Andrews et al., 2007) that triggers intense emotional responses provoking changes in HPA-axis activity and, consequently, eliciting strong cortisol responses (Dickerson, Mycek, & Zaldivar, 2008). Therefore, in our first study w e use 10-minute-long public speaking presentation to assess individual's stress responses. Minor stressors are another source of stress that people have to face frequently and reflect the daily stress load.. However, not every person will interpret. them as stressful or respond in the s a m e w a y than other person m a y do.. These. differences m a y be explained by s o m e personality traits, in particular, neuroticism (N). A s w e mention previously, people high in N are characterized by the tendency to perceive more stressors and to respond negatively to these situations than people low in this trait (Lahey, 2009). studied. only. participants. Thus, in our last two studies presented here, w e. with extreme. N-scores. to denote. clearly. differences. between them in relation to daily stress.. Psychological or perceived stress can be assessed by using self-reports that collect information about the number, frequency and intensity of the. stressors. experienced during a period of time (e.g., hassles, recent life experiences, etc.)..

(33) However these instruments present s o m e limitations, mostly due to a high intra- and between-subjects variability in their ratings.. For instance, a person w h o has to. describe its level of stress in several time points could use the s a m e value but denoting something different (intra-subjects) or, two people using the s a m e score m a y signify something completely different from one participant to another ( b e t w e e n subject).. Finally, the instruments used to evaluate stress m a y be not sensitive. e n o u g h to denote changes over time.. Therefore, in order to obtain a reliable. m e a s u r e of perceived stress w e included in our last study the S R L E scale.. This. scale has been shown to be a decontaminated hassles m e a s u r e to determine accurately how m u c h everyday stressors affect physical and mental health (Kohn & Macdonald,. 1992),. and. sensitive. enough. to detect. individual. differences. and. changes over time (de Jong, T i m m e r m a n , & E m m e l k a m p , 1996).. To. complement. this. subjective. measure. (SRLE),. we. also. include. an. "objective" m e a s u r e to increase the reliability of our results and, to demonstrate that stress is not only affecting us psychologically, but also physiologically.. Indeed, w h e n. w e are experiencing stress, immediately our brain generates a signal that provokes a physiological response activating the HPA-axis (e.g., Gaab, Sonderegger, Scherrer, & Ehlert, 2006).. A s a result, our organism gets ready to deal with daily stress.. A. g o o d and reliable biomeasure of stress is the hormone, cortisol - end product of HPA-axis activity..

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(35) 4.. Cortisol. Cortisol is the main glucocorticoid hormone responsible for mobilizing energy to deal with daily activities and contributes fundamentally to the maintenance of basal and stress-related homeostasis ( M c E w e n , 2003).. However, Selye (1936). recognized the paradox that the physiologic systems activated by stress can not only protect and restore but also d a m a g e the body.. T h e primary biological m e c h a n i s m. underlying stress regulation and adaptation is the. hypothalamic-pituitary-adrenal. (HPA) axis (see Figure 2).. Figure. 2.. Illustrates the physiological. hypothalamic-pituitary-adrenal. (HPA). cascade. axis. and. involved the. in the. regulation. f e e d b a c k after the cortisol secretion. A d a p t e d from Tittp://total-bodypsychology.com .au/stress-response-hpa-axis/"..

(36) T h e H P A axis activity is governed by the secretion of corticotrophin-releasing h o r m o n e (CRH) and vasopressin (AVP) from the hypothalamus, which in turn activates the secretion of adrenocorticotrophic hormone (ACTH) from the pituitary, w h i c h finally stimulates the secretion of the glucocorticoids from the adrenal cortex, s u c h as cortisol. O n c e the glucocorticoids are secreted into the blood stream, they interact with their receptors in multiple target tissues including the HPA axis.. The. activated glucocorticoid receptor (GR), in turn, induces a f e e d b a c k inhibition signal on both C R H and A V P from the hypothalamus and directly on the secretion of A C T H from pituitary that leads the reduction of H P A axis activity. Glucocorticoids not only influence the activity of pituitary but also m a n y other functions of the central nervous system s u c h as, arousal, cognition, m o o d and sleep, also the activity and direction of intermediary metabolism, the maintenance of a normal cardiovascular tone, the activity and quality of the i m m u n e and inflammatory reaction, including the manifestations of the sickness syndrome, as well as growth and reproduction (Chrousos & Kino, 2007).. Glucocorticoids influence the brain,. regulating the neuronal survival, neurogenesis, and sizes of complex anatomical structures s u c h as the hippocampus, the acquisition of new m e m o r i e s and the emotional appraisal of events (Herbert et al., 2006).. In that way, any generalized. change in the glucocorticoid signalling system w o u l d be followed by corrective, compensatory changes in the activity of the H P A axis. However, s o m e t i m e s this "compensatory" activity does not occur.. In fact,. w h e r e a s cortisol generally helps the organism f a c e daily life activities, disturbed patterns of cortisol secretion are potentially detrimental in long-term, for instance, the deregulation of daytime cortisol activity has indeed been associated with stress-.

(37) related pathologies, including depression, post-traumatic stress disorder, anxiety, externalizing behaviours, and cognitive deficits, as occur with chronic stress.. 4.1. Daytime Cortisol circadian cycle. Daytime cortisol cycle refers to the cortisol secreted along the day. cortisol. secretion. presents. a. circadian. rhythm. of. 24. hours. that. The. follows. a. characteristic diurnal rhythm with several secretory episodes of short duration and high amplitude (Fries, Dettenborn, & Kirschbaum, 2009).. Under normal conditions,. the typical diurnal cortisol profile shows a sharp rise upon awakening, called cortisol awakening response (CAR), w h e r e thereafter there is a steady decline over the rest of the day with lower levels in the evening and night (Tsigos & Chrousos, 2002). T h e C A R appears to be a distinct feature of the hypothalamus-pituitary-adrenal (HPA) axis, superimposing the circadian rhythmicity of cortisol secretion (Fries, Dettenborn, & Kirschbaum, 2009) as it adds a substantial incremental effect to the linear trend of increasing. cortisol. concentrations. Kudielka, Scholtz & Wust, 2007).. in the early. morning. hours. (Wilhelm,. Born,. More importantly, the a w a k e n i n g itself is a. consistent, recurring, and strong stimulus for H P A activity (Wilhelm et al., 2007).. 4.1.1. Cortisol Awakening Response (CAR). T h e C A R is a discrete and distinctive part of the cortisol circadian cycle.. In. healthy adults salivary free cortisol concentrations increase by between 50 and.

(38) 1 6 0 % in the first 30-45 min immediately post-awakening (approximate. average. increase of 9 nmol/l, range 4 - 1 5 nmol/l, estimated to be equivalent, to about three secretory episodes; Clow, Thorn, Evans, & Hucklebridge, 2004). This response w a s coined the "Cortisol A w a k e n i n g Response" (CAR) by Federenko et al. in 2 0 0 4 (see Figure 3).. s1 1.25-. /. \. /. 1.00-. sO. .75". CAR. l\ » •. I. .50". \ \. * •. \u s3. i : • : : i : :. .25". .00-. i. i : : : i : :. s4. *. *. Time from awakening (hours). Figure period. 3.. Characteristic of the cortisol diurnal profile during 12hs. where. the. Cortisol. Awakening. Response. (CAR). is. represented, between 0h (wake-up) and first 45 minutes (0.75h) after awakening.. Pruessner et al. (1997) w e r e the first w h o proposed that the. repeated. assessment of this cortisol increase after a w a k e n i n g in saliva might represent a useful and easy index of cortisol regulation. I n d e e d , the C A R has b e e n attracting.

(39) attention from researchers for a number of reasons.. First, the C A R is one of the. most important a n d easy p a r a m e t e r of H P A axis function to measure. S e c o n d , the CAR. is under s o m e w h a t. independent. control from. cortisol output d u r i n g the. remainder of the day, a n d associations between the C A R a n d cortisol s a m p l e d later in the day are quite low (Edwards, Evans, Hucklebridge, & Clow, 2001). Third, twin studies have d o c u m e n t e d a genetic influence o n the C A R that is distinct from the heritability of daytime cortisol levels (Kupper et al., 2005).. Finally and. very. important, the magnitude of the C A R appears to be associated with psychosocial factors and health in potentially significant w a y s .. In fact, Chida and Steptoe (2009). suggest that the magnitude of the C A R m a y be a distinctive indicator of HPA function and dysfunction. Early psychological studies of the C A R indicated that the response w a s heightened a m o n g individuals experiencing job stress, overload, and low self-esteem (Schulz, Kirschbaum, Pruessner, & Hellhammer, 1998; Pruessner, Hellhammer, & Kirschbaum, 1999; Wüst, Federenko, Hellhammer, & Kirschbaum, 2000).. Others. suggest that the C A R might be a n indicator of chronic psychosocial stress (e.g., Bhagwagar, Hafizi, & C o w e n , 2005). be a marker of neuroendocrine. Furthermore, larger C A R s w e r e suggested to. activation as the. individual contemplated. challenges of the day a h e a d (Chida and Steptoe, 2009).. the. B y contrast, a diminished. C A R appeared to be present in people suffering from post-traumatic stress disorder (de Kloet et al., 2006; W a h b e h & O k e n , 2013), m e n with systemic hypertension (Wirtz et al., 2007), and w o m e n with mild or moderate depression (Stetler & Miller, 2005)..

(40) Nonetheless, the C A R is particularly volatile and variable intra- and b e t w e e n subjects.. This variability has been reported at the awakening time but not later. during the day (Kupper et al., 2005) and may be affected by biological m e c h a n i s m s of control.. T h e s e m e c h a n i s m s are the suprachiasmatic nucleus circadian clock. (Postnova, Fulcher, B r a u n , & R o b i n s o n , 2013), the hippocampal regulation (Fries et al., 2009), and biological processes associated with sleep-wake cycles (Smyth, Clow, Thorn, Huckebridge, & Evans, 2013).. Therefore, in our second and third. study, due to the fact that cortisol secretion during the first 45 min is too volatile, w e also evaluated the area under the curve (AUC), which represents the total cortisol secreted during a predefined period of time, w h i c h s e e m s to be more stable than the C A R to evaluate changes over time.. 4.1.2. Area under the curve (AUC). T h e area under the curve (AUC) is another cortisol secretion parameter that provides relevant information about the functioning of HPA.. T h e A U C is often used. to estimate total cortisol secretion during a predefined time period (Hansen, Garde, & Persson, 2008).. In research and clinical settings, the salivary cortisol m e a s u r e s are. used as a physiology indicator of responsiveness of the HPA axis to determine the health c o n s e q u e n c e s of stress. In research involving repeated m e a s u r e m e n t s of a response variable, there is a need to derive parameters that s u m m a r i z e the information contained in the multivariate data.. T h e A U C is a good parameter to get this information and it is. c o m p u t e d following a trapezoidal formula separated into triangles and rectangles..

(41) Pruessner,. Kirschbaum,. Meinlschmid,. &. Hellhammer. (2003). provide. a. simple. formula for the computation of two types of A U C that reveal different information (see Figure 4): A U C g (area under the curve to the ground) and A U C i (area under the curve to the increase).. Figure 4. T i m e course of an artificial dataset with six measurements; the triangles and rectangles illustrate the composition of the area under. the. curve. (AUC).. 'ml'. to. 'm6'. denote. the. single. measurements, and ' t 1 ' to 't5' denote the time interval between the measurements. area. under. the. A d a p t e d from "Two formulas curve. represent. concentration. versus time-dependent. Kirschbaum,. G.. Meinlschmid,. Psychoneuroendocrinology, Science Ltd.. measures change". and. 28, p. 918.. D.. H.. for computation of. total. of the hormone. by J. C. Pruessner, C. Hellhammer,. 2003,. Copyright 2 0 0 3 by Elsevier.

(42) T h e A U C i is calculated with reference to the baseline m e a s u r e m e n t a n d it ignores t h e distance from zero for all measurements a n d emphasizes t h e changes over t i m e . A U C g is t h e total area under t h e c u r v e , a n d it takes into account both sensitivity intensity. (the difference between t h e single m e a s u r e m e n t s from each other) a n d (the distance from these measures from ground), a n d it is a s s u m e d to be a. measure more related to total h o r m o n e output.. B o t h formulas are basically simple additions of areas consisting of triangles and rectangles:. AUC. q. 9. =. c. ]. Er="i ^i=. ^" '=(|. (m +mi)-tj ii+1). 1. (. m. (. 2. '. +. i. ). +. m. '. ). ,. t. ')-(. m. t. i-!| '). In this study w e focused o n t h e A U C g parameter a n d w e divided it in t w o different parameters: A U C 0 _ 4 5 m i n (the area under t h e curve the first 4 5 m i n after awakening) and A U C 0 7 5 h _ 1 2 h (also called "total Cortisol secretion" - T C S in our last study), w h i c h represent t h e cortisol secreted during t h e remainder of t h e 12h period after C A R (see Figure 5 ) ..

(43) AUCO 45min. 0.00h. 0.75h. 2.50h. AUC075h_12h. 8.00h. 12.00h. Time from awakening (hours). Figure. 5.. 0.00h. 0.75h. 2.50h. 6.00h. 12.00h. Time from awakening (hours). Plots showing two forms of A U C g : A U C 0 _ 4 5 m i n. and. A U C 0 7 5 h _ 1 2 h or T C S .. W e have described how the cortisol diurnal profile normally behaves under daily situations and several w a y s to assess the functioning of H P A - a x i s obtained from saliva samples. However, this daytime cortisol profile can be s u p p l e m e n t e d by episodic Cortisol. reactivity. to unpredictable,. uncertain, and novel. psychological. challenges (Bosch et al, 2009).. 4.2. Cortisol Reactivity. T h e HPA-axis is a major endocrine system adapting the organism to bodily and environmental challenges by inducing behavioral and physiological c h a n g e s , improving the organism's ability to adjust homeostasis (Tsigos & Chrousos, 2002). Cortisol plays a crucial role in the organism's efforts to adjust to these challenges. In fact, under unpredictable, uncertain, and novel challenges an increase in cortisol secretion is considered an adaptive response to a mismatch between the individual.

(44) needs and factors in the environment (de Kloet, 2003; M c E w e n , 2000).. This. reactivity has widely been considered an endocrine index of the stress response (Miller, C h e n , & Cole, 2009).. However, s o m e studies have been found that not. always there is an increase in the cortisol response during the acute stressful situation, but also a flat or blunted cortisol response (e.g., Loft et al., 2007; Roy, 2004; Saxbe, Repetti, & Nishina, 2008), w h i c h have been associated with a poor or less adaptive response.. A n excessive d e m a n d over time on energy mobilization due to frequent stress, failed shutdown of the stress reactivity system or inadequate response to challenges, generates an allostatic load ( M c E w e n , 1998).. M c E w e n (2000) define. allostatic load as a result of the effort that our body as to tolerate trying to keep the allostasis (homeostasis) during stressful d e m a n d s .. This load at s o m e point might. affect not only the HPA axis function ( M c E w e n , 2008; Oswald et al., 2006), but also the autonomic nervous system function (Appelhans & Luecken, 2006; Chida & Hamer, 2008; Thayer, A h s , Fredrikson, Sollers, & Wager, 2011), and. produce. changes in the structure of the brain with a decline of cognitive functions (Herbert et al., 2006; M c E w e n , 2012; Lupien, M c E w e n , Gunnar, & Heim, 2009). Concretely, the accumulation of this load (called overload by M c E w e n ) s o m e t i m e s lead to target tissue. pathology,. as. occurs. in chronically. stressed. or. depressed. individuals. (Chrousos 2000; Gold & Chrousos, 2002).. Although all h u m a n beings encounter stressful events, they do not respond identically to such experiences.. W h e r e a s s o m e individuals adapt flexibly to the. changing d e m a n d s of stressful experiences, others cope far less effectively.. Thus,. in relation to these differences in cortisol responses, a large number of studies have found a substantial inter- and intra-individual variability to similar challenges (Chida &.

(45) Steptoe, 2009; Kudielka, Hellhammer, & Wüst, 2009; Thorn, Hucklebridge, Evans, & Clow, 2009) and it has been suggested that personality traits m a y play a significant role in their explanation (LeBlanc, Ducharme, & T h o m p s o n , 2 0 0 4 ; Oswald et al., 2006; Pruessner et al., 1997)..

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(47) 5.. Personality and Cortisol: relation between concepts. W h e n e v e r the brain needs energy, the HPA-axis will help to allocate glucose to. the. brain,. increasing. this. dynamic. conditions (Peters et al., 2004).. (higher. Cortisol. peaks). under. stressful. A s w e mentioned above, there is s o m e inter- and. intra-individual variability in cortisol secretion, and part of this variability m a y be explained by personality traits.. Associations between cortisol and personality have. been f o u n d under stressful situations (acute stress) and under daily activities (daily stressors). In relation to acute stress, associations between neuroticism and elevated urinary cortisol have been d o c u m e n t e d in a c a d e m i c e x a m s (Garcia de la Banda, Martinez-Abascal, Riesco, & Perez, 2004) and mental arithmetic tasks (Habra, Linden, A n d e r s o n , & W e i n b e r g , 2003). On the contrary, neuroticism w a s also linked to blunted salivary cortisol responses to public speaking (Garcia de la Banda, Martinez-Abascal, Pastor, et al., 2004), mental arithmetic tasks (Phillips, Carroll, Burns, & Drayson, 2005), and cold exposure (LeBlanc & Ducharme, 2005). are also other personality traits that have been related with cortisol.. There. A diminished. cortisol response to stress has been linked to extraversion (Garcia de la Banda, Martinez-Abascal, Pastor, et al., 2004; Kirschbaum et al., 1995; Oswald et al., 2006), but directionally opposite results have been reported by LeBlanc and Ducharme (2005). Social. O p e n n e s s has been linked to higher cortisol levels evaluated by the Trier Stress. Test. (TSST;. Kirschbaum,. Pirke,. &. Hellhammer,. 1993),. while. participants low in agreeableness (who tend to be mistrusting and hostile) secreted more cortisol c o m p a r e d to people that have higher scores in agreeableness (in males; Suarez, Kuhn, Schanberg, Williams, & Z i m m e r m a n , 1998)..

(48) On the contrary, conscientiousness, considered a buffer for stress (Korotkov, 2008) and a g o o d predictor of health and longevity (Friedman, 2008), has not been associated with cortisol secretion (Nater, H o p p m a n , and Klumb, 2010; Oswald et al., 2006; Schoofs, Hartmann, & Wolf, 2008). previous studies between psychoticism. Finally, no association has been f o u n d in a n d cortisol (Kirschbaum, Bartussek,. &. Strasburger, 1992; Schommer, Kudielka, Hellhammer, & Kirschbaum, 1999). In relation to daily stress, a small body of research has tried to relate basal cortisol and personality.. In particular, the trait of neuroticism.. In fact, neuroticism. has been not only associated to psychological stress but also with excessive cortisol secretion that predisposes individuals to psychopathology (Lahey, 2009; Ormel et al., 2013).. However, the direction of this association remained inconclusive, since. s o m e studies found increased, showing individuals with high N scores to have greater cortisol levels (Nater, H o p p m a n n , & Klumb, 2010; Portella, Harmer, Flint, C o w e n , & Goodwin, 2005) and others decreased cortisol concentrations (Hauner et al., 2008; LeBlanc & Ducharme, 2005).. In addition, Mikolajczak et al. (2010) f o u n d. that high N w a s associated with significantly less flexibility of the CAR, w e e k e n d and w e e k d a y profiles are c o m p a r e d .. when. Also a flatter diurnal cortisol slope. has been linked to higher N, but only in male participants (Hauner et al., 2008). Nonetheless, in a majority of studies, the predicted link between high N and high basal cortisol it has not been found (Adler, W e d e k i n d , Pilz, Weniger, & Huether, 1997; C h a n , Goodwin, & Harmer, 2007; Ferguson, 2008; Gerritsen et al., 2009; Hill, Billington, & Krägelog, 2013; Riese, Rijsdijk, Rosmalen, Snieder, & Ormel, 2009; Schommer, Kudielka, Hellhammer, & Kirschbaum, 1999; V a n Santen et al., 2011). This generally inconsistent picture in regard to personality and cortisol might partly reflect methodological differences.. For example, early researchers used the.

(49) Eysenck Personality Questionnaire-Revised (EPQ-R; Eysenck & Eysenck, 1985b) to assess personality measures ( S c h o m m e r et al., 1999) while later researchers relied on the N E O. Personality. Inventory (Costa & McCrae,. 1985) or selected. other. personality questionnaires such as the Freiburg Personality Inventory (Fahrenberg, Hampel, & Selg,. 1989). used by. Brandtstädter,. Baltes-Götz,. Kirschbaum,. and. Hellhammer (1991). In our three studies w e include both questionnaires to solve this problem and to guarantee the reliability of our results.. A n o t h e r problem is that in. s o m e studies laboratory stressors have been used with a lack of validation of their stress-eliciting properties.. independent. Speak in front of an audience, is a. proven social stressor and has b e c o m e c o m m o n l y used in the study of stress (Schoofs, Hartmann, & Wolf, 2008). Therefore, in our first study w e used 10-minutes public presentation as an acute stressor to assess the stress response.. A rigorous assessment of cortisol is critical in this type of studies as well. However, w h e n cortisol reactivity has been assessed, only a pretest and posttest m e a s u r e has been typically used. Many studies used the first saliva sample, before the stressful situation, as a pretest condition, without taking into consideration that this cortisol level value m a y be influenced by anticipation.. Therefore, in both. stressful and basal cortisol studies w e include baseline measures of cortisol a w e e k before to the specific situation (acute or daily stress), to control the effect of anticipation or novelty respectively.. Additionally, m a n y researchers exploring personality and cortisol activity have relied on samples consisting of either adults or very y o u n g children (Bouma, Riese, Ormel, Verhulst, & Oldehinkel, 2009). W e consider that late adolescence represents the ideal time for the evaluation of cortisol, because is the period before personality and cortisol patterns have been further affected by a long history of major life events.

(50) or psychopathology, permitting a relatively "clean" observation of the inter-correlation pattern between cortisol and personality traits (Hauner et al., 2008). For that reason this population has been our target sample in the three studies.. In s u m , w e have used both personality questionnaires, naturalistic a c a d e m i c settings to assess acute stress, including baseline cortisol measures in all studies, and f o c u s e d on y o u n g population.. In addition, in our second and third study, w e. used both electronic monitoring devices and manual registration of the exactly time w h e n each saliva s a m p l e w a s collected to increase compliance.. W e included as. well several control features that could be affecting cortisol secretion, such as stress level, f o o d or drinks intakes, smoking status, medication, etc.. Finally,. sample. characteristics w e r e also controlled: similar number of participants in relation to sex, participant's homogeneity in age and education, and careful selection of extreme high versus low scores in neuroticism..

(51) 6.. APMR. as. an. intervention. to. reduce. psychological. and. physiological stress. Relaxation is a behavioural intervention used to release bodily tensions and promote positive feelings to deal with stressors.. Relaxation is one of the primary. c o m p o n e n t s of all kinds of meditation, w h i c h induce a pleasant and deep relaxed state of body and mind (Hussain & Bhushan, 2010). techniques are a central c o m p o n e n t. More importantly, relaxation. in most comprehensive. programs for. the. treatment of stress-related problems (Benson, Beary & Carol, 1974), w h i c h is the focus of our study. Jacobson. (1938) discovered that by systematically tensing and. relaxing. different muscle groups and by learning to focus on and discriminate between the resulting sensations of tension and relaxation, a person m a y almost alleviate muscle contractions and experience a feeling of deep relaxation (Bernstein & Borkovec, 1973).. Progressive Muscle Relaxation (PMR) training produces extraordinarily low. levels of muscle tension, and that patients suffering from a variety of psychological and somatic disorders experience significant relief w h e n they practice this technique (Lehrer, 1978).. However, even w h e n P M R w a s originally conceived by J a c o b s o n ,. requiring more than 40 individual sessions, w a s not until 1973 w h e n Bernstein and Borkovec streamlined Jacobson's training approach and specified in a step-by-step manner the procedures for administering relaxation training to clients in 8 to 12 sessions.. Bernstein. and. Borkovec. provided. a. protocol. called. Abbreviated. Progressive Muscle Relaxation (APMR), that involves shorter sessions and only 16 muscle groups rather than the nearly 30 indicated by J a c o b s o n ..

(52) A P M R is one the most techniques used with a long history of studies showing positive results based on clinical population with several diseases and sub-clinical population. Certainly, A P M R has s h o w n to produce effective psychological changes w h i c h include, reduced anxiety levels (Rausch, Gramling, & A u e r b a c h ,. 2006),. decreased perceived stress (Emery, France, Harris, N o r m a n , & V a n Arsdalen, 2008) and increased feelings of relaxation (Pawlow & Jones, 2002), and physiological benefits, such as decreased cortisol levels (Krajewski, Saverland, & W i e l a n d , 2 0 1 1 ; Pawlow & Jones, 2002, 2005). Due to its historical pedigree, its well-defined and easily taught procedures, its comparatively low cost delivery, and s o m e evidence of efficacy, A P M R has b e c o m e justly popular as a promising stress-reduction intervention. Given such promise, it is an ideal candidate for more detailed scrutiny of its efficacy.. However, mostly of the. existing studies that assess changes in cortisol present s o m e limitations in their designs.. For instance, using only a single session of A P M R for 2 0 min and just one. cortisol m e a s u r e taken immediately before and after (Dolbier & Rush, 2012; Pawlow & Jones, 2005), or applying two A P M R sessions spaced seven days apart, but again assessing cortisol immediately before and after each session (Pawlow & Jones, 2002), or using good cortisol measures but very small s a m p l e size (n=7) in both control and experimental groups (Krajewski et al., 2011). So, even w h e n in essence all these studies are positive in suggesting that cortisol decreases. immediately. before and after A P M R sessions (Dolbier & Rush, 2012; Pawlow & Jones, 2002, 2005) or during a six-month period of daily practice (Krajewski et al., 2011), none of these studies examine changes in measures designed to be stable estimates of prevailing cortisol levels, such as A U C , in a meaningful period o n e - w e e k before and after a well-controlled intervention..

(53) Therefore, in our last study, a carefully constructed cortisol m e a s u r e (TCS) and an appropriate self-report (SRLE) w a s used in order to provide a physiological and psychological markers of stress.. robust. W e investigated w h e t h e r 5. consecutive days of A P M R training impacts on 'prevailing' levels of stress comparing o n e - w e e k before and o n e - w e e k after the intervention, rather than just its efficacy in reducing spot measures of stress from start to finish a single session of A P M R . also examine whether the efficacy of this intervention neuroticism.. may. be modulated. We by.

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(55) Chapter 2. Cortisol response under a stressful situation: Public speaking.

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(57) Introduction. Cortisol, end product of the HPA-axis, follows a circadian rhythm (24 hours) of secretion with a significant peak in the first 0.75h after awakening allowing us to face daily activities.. However, this basal rhythm is s u p p l e m e n t e d by episodic cortisol. reactivity under stressful situations. Current research shows that university is a very stressful time for at least 5 0 % of the student body (Regehr, Glancy, & Pitts, 2013). Potential stressors derive from the need to adjust to heavy a c a d e m i c d e m a n d s and the need for students to immerse themselves in a novel social network (Dolbier & Rush, 2012).. Public speaking is one of the most frequent stressors. students. experience during their a c a d e m i c training and is a proven social stressor used to assess cortisol reactivity.. Finally, w e have described previously that personality. plays a significant role in the w a y people react under similar stressful conditions, and therefore s o m e of these traits are associated with differences in cortisol response to challenge.. However, in prior research several inconsistencies have been found in. the relationship between personality and cortisol reactivity that might partly reflect s o m e methodological issues.. Therefore in our study w e w a n t e d to control several factors that in our opinion might help to clarify s o m e of these inconsistencies. validity. of. personality. assessment,. we. used. First, in order to increase the both. EPQ-R. and. NEO-FFI. questionnaires. S e c o n d , w e used a 10-minute-long class public presentation to evaluate cortisol response, as a students' real life stressor (opposite to laboratory stressors).. Third, in order to increase methodological rigor w e include additional. baseline cortisol sampling taken on a previous day to the stressful situation but at the.

(58) s a m e time that the public speaking samples w e r e taken.. Finally, because late. adolescent represents the period before personality and cortisol patterns have been further affected by a long history of major life events or psychopathology, will permit us a "clean" observation of the relationship between cortisol and personality, w e focused on this group population.. S u m m i n g up, the aim of this first study w a s to c o m p a r e salivary cortisol secreted by a group of university students in two different conditions: non-stressful and stressful. traits.. Differences in cortisol reactivity will be correlated with personality. Our first hypothesis w a s : public speaking (stressful condition) will increase. cortisol secretion c o m p a r e d with a daily a c a d e m i c activity (baseline condition).. We. anticipated also that cortisol reactivity w o u l d be positively related to Openness, Agreeableness. and Conscientiousness,. and negatively related to. Extraversion,. Neuroticism and Psychoticism.. Method. Participants. Seventy-five students from University of Balearic Islands (UIB) participated in our study, 56 w e r e w o m a n and 19 w e r e m e n (mean age = 20.9 years).. All w e r e. volunteers enrolled in a Psychology of Personality class at UIB across. three. a c a d e m i c intakes with no exclusion criteria except the provision of both complete questionnaire and complete cortisol data..

(59) Instruments. -. Participants completed the 83-items of the Spanish version of the. Eysenck. Personality Questionnaire-Revised (EPQ-R; Eysenck & Eysenck, 1997), using a dichotomous. yes/no. response.. This. questionnaire. provides. three. major. personality dimensions: Extraversion (E), Neuroticism (N) and Psychoticism (P). -. Participants also completed the revised short-form version of the Spanish N E O Five Factor Inventory ( N E O - F F I ; Costa & McCrae, 1999). This inventory consists in 60-items of w h i c h m e a s u r e the five major personality dimensions: Neuroticism (N), Extraversion (E), O p e n n e s s (O), Agreeableness (A) and Conscientiousness (C). Participants responded on a 5-point Likert scale from 0 (totally disagree) (totally. to 4. agree).. Procedure. At the start of the semester, students completed the E P Q - R and the NEO-FFI scales, and after providing written informed consent, four salivary samples w e r e taken to assess cortisol levels during the late afternoon (between 4 and 6 pm).. Two. baseline samples w e r e taken on a day during a class period w h e r e the student had no paper, examination, or class participation at approximately the s a m e time w h e n the samples w e r e taken during the stressful day. T w o stress samples w e r e taken for each participant during a class performance, w h e r e the student providing the sample had to give a 10-minutes presentation to the class and answer classmates' questions after the presentation. T h e first s a m p l e w a s taken just prior the presentation and the second 30-minutes after (see Figure 1)..

(60) CONDITION 2. NONSTRESSFUL. 3. STRESSFUL (Public Speaking). EPQ-R NEO-FFI Y. C Figure. INFORMED CONSENT. ^ \. 1. Procedure and saliva sample collection.. Salivary Cortisol samples w e r e collected with a cotton s w a b c h e w e d for one minute, stored in a c a p p e d plastic vial ("Salivette" Sarstdet Inc.).. T h e s e samples. w e r e centrifuged at 3000g for 3 minutes, and then the filtrates w e r e stored frozen at 80°C until analysis.. Before analysis, the samples w e r e t h a w e d , mixed, centrifuged. and analyzed without pre-treatment. T o reduce error, all samples of each participant w e r e analyzed in one assay. Salivary cortisol w a s m e a s u r e d using a modification of the Bayer A D V I A Centaur cortisol assay, a competitive direct chemiluminescence's i m m u n o a s s a y that uses a rabbit polyclonal antibody. E n d o g e n o u s cortisol contained in the samples competes with a cortisol labeled with acridinium-ester for the binding sites of the anti-cortisol rabbit polyclonal antibody-coated paramagnetic particles. T h e intra- and inter-assay coefficients of variation w e r e less than 1 0 % for 0.30 ug/dL of cortisol..

(61) Statistical. analysis. A two-way repeated measures analysis of variance ( A N O V A ) w a s used to test the effects of stress/baseline and first/second s a m p l e of cortisol, and correlations. were. carried. out. to. examine. associations. between. Pearson. cortisol. and. personality m e a s u r e s .. Results. Table. 1. provides. a. summary. of. descriptive. dimensions and cortisol levels at the two conditions.. statistics. for. personality. Distributions of cortisol data. w e r e substantially positively s k e w e d , so values w e r e analyzed as logarithmically transformed with one extreme outlier r e m o v e d .. Table 1. Descriptive. statistics. for personality. traits and cortisol. measures. Minimum. Maximum. M. SD. NEO-FFI Neuroticism. 1.00. 44.00. 23.36. 8.63. NEO-FFI Extraversion. 6.00. 46.00. 31.37. 8.37. NEO-FFI O p e n n e s s. 11.00. 48.00. 31.91. 7.43. NEO-FFI Agreeableness. 12.00. 43.00. 28.59. 6.21. NEO-FFI Conscientiousness. 6.00. 40.00. 27.56. 7.30. E P Q - R Extraversion. 6.00. 19.00. 13.13. 3.30. E P Q - R Neuroticism. 2.00. 23.00. 12.09. 5.01. E P Q - R Psychoticism. 0.00. 19.00. 5.03. 3.27. CortBL1. 0.02. 2.19. 0.55. 0.38. CortBL2. 0.09. 2.00. 0.44. 0.28. CortPS1. 0.24. 3.05. 0.82. 0.60. CortPS2. 0.10. 2.40. 0.71. 0.47. Note: Cortisol levels are presented in ug/dL. CortBLI: Baseline Cortisol at time 1 taken at the beginning of an ordinary class. CortBL2: Baseline cortisol at time 2 taken at the end.

(62) of that class. CortPS1: Stress cortisol at time 1 taken at the beginning of a class where participants had to speak in public. CortPS2: Stress cortisol at time 2 taken at the end of the class. Two-way. repeated-measures. ANOVA. was. performed with the first. and. second cortical a s s e s s m e n t s on the s a m e day and non-stressful (baseline) v s . stressful (stress) condition (see Figure 2 ) . A significant main effect w a s obtained for 2. the non-stressful /stressful factor ( F ( 1 , 73) = 34.99, p = .000, partial n = .32, n o n transformed M. no-stress. = .50; M. stress. = .77), also for first (before) vs. second (after) 2. sample ( F ( 1 , 73) = 21.20, p = .000, partial n = .22, non-transformed M second. = .58).. first. = .69; M 2. There w a s no interaction effect ( F ( 1 , 73) = 1.15, p = .29, partial n =. .02).. Figure. 2.. Cortisol secretion before and after the presentation in baseline and. stressful condition.. W e e x a m i n e d next correlations between personality and cortisol measures. All. personality. measure. distributions. were. plausibly. normal. except. for.

(63) Conscientiousness. and for Psychoticism, which w e r e negatively and. s k e w e d respectively.. positively. B o t h , therefore, underwent a square root transformation (with. prior reflection for negative skew).. Pearson correlation coefficients w e r e. between cortisol scores and the personality variables.. run. T h e two cortisol measures. taken at the beginning and at the end of both baseline (CortBL) and stress (CortPS) conditions w e r e averaged and e x a m i n e d to reflect m e a n cortisol on each day; both had significant positive skewness and w e r e log transformed.. T h e difference score,. reflecting the cortisol response to the stressor, w a s calculated by subtracting the baseline average from the stress day average. T h e distribution of this variable w a s plausibly normal without transformation.. T h e correlations. between. personality. variables and the three cortisol scores appear in Table 2. Neuroticism scores on the E P Q - R and N E O - F F I questionnaires w e r e positive and highly correlated (.73), as it w a s Extraversion (.61).. Psychoticism (EPQ-R) and Conscientiousness (NEO-FFI). w e r e negatively correlated (-.48). Conscientiousness. (.31). and. Cortisol response to stress w a s. inversely to. Psychoticism. (-.31).. No. related. to. significant. correlations w e r e found between personality and the average scores at baseline and stressful condition, except a small negative relationship between baseline cortisol and the personality trait of Conscientiousness (-.23).. Finally, although the s a m p l e w a s primarily females, and therefore there w e r e not e n o u g h males to m a k e a powerful analysis, it is possible that being male or f e m a l e m a y have s o m e influence on the cortisol response.. However,. multiple. regression analyses controlling for gender and also for year of recruitment into the study did not significantly alter the univariate effect sizes reported above..

(64) Table 2. Pearson. product. moment. NEO. correlations. NEO. for cortisol. NEO. and personality. NEO. dimensions. sqrNEO. EPQ. EPQ. Cort Log CortLB Log CortPS. Neuroticism Extraversion Openness Agreeableness Conscientiouness Extraversion Neuroticism NEO Neuroticism NEO Extraversion. -.08. NEO Openness. .12. .23*. -.06. .20. .02. -.39***. -.03. -.11. .16. EPQ Extraversion. -.22. .61***. -.01. .01. -.02. EPQ Neuroticism. .73***. -.11. -.01. -.04. -.14. -.34**. .14. .14. .38***. -.30**. -.48***. .04. NEO Agreeableness Sqr(reflex)NEO Conscientiousness. EPQ sqr Psychoticism. Note:. .02. PS-BL. -.06. -.09. -.14. -.16. -.14. -.02. -.01. .08. .01. -.01. .06. .08. -.23*. .02. .31**. -.07. -.13. -.07. -.03. .13. .15. .02. -.19. -.31**. logCortBL = log Baseline cortisol. LogCortPS = log Public Speaking cortisol. CortPS-BL = cortisol changes between. baseline and public speaking scores. s q r N E O Conscientiousness = square root of reflex of N E O Conscientiousness scores. s q r E P Q Psychoticism = square root transformation of EPQ Psychoticism scores. * p < .05, ** p < . 0 1 , *** p < . 0 0 1 ..

(65) Discussion. Our. results. confirm. that. public. speaking. increased. significantly. cortisol. secretion w h e n c o m p a r e d with a non-stressful a c a d e m i c activity, validating our task as an effective stressor to trigger the H P A - a x i s activity. partly c o n f i r m e d : Conscientiousness. and. Psychoticism. Our s e c o n d hypothesis is appear to be the. only. personality traits related with cortisol secretion levels, both playing a relevant role in the response to stress.. Particularly, conscientiousness w a s associated with an. e n h a n c e d cortisol response to stress, w h i c h it has been associated with a better adaptation behavioural style to stress conditions (Roy, 2004). psychoticism w a s related with a blunted (plain) cortisol response.. On the contrary, Blunted cortisol. reactivity m a y reflect poorer response to the stressful d e m a n d s , could be associated with certain underlying deregulation of the HPA system (Phillips, Carroll, Burns, & Drayson, 2005), and persistent aggression (McBurnett, Lahey, Rathouz, & Loebeer, 2000).. Indeed, blunted cortisol reactivity has been implicated in the development of. psychopathic personality traits (O'Leary, Loney, & Eckel, 2006)..

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(67) Chapter 3. Cortisol response under daily situations in participants with extreme scores on neuroticism.

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(69) Introduction. S o far,. our results. have s h o w n. that. Conscientiousness. is directly. and. Psychoticism is inversely associated with cortisol reactivity produced by an acute stressor as public speaking. But, what happens with cortisol w h e n w e are not facing a particular stressful situation? A r e personality traits also associated to daily cortisol secretion?. T h e "wear and tear" model of stress ( M c E w e n & Wingfield, 2010) introduced the concept of allostasis, maintaining stability through changes, to refer to the neural, endocrine and immune activation with w h i c h our body reacts w h e n facing short-term stress. On the contrary, they used allostatic load to allude to the price the body pays for this repetitive effort over time resulting in chemical imbalances and perturbation in (e.g. cortisol) diurnal rhythms ( M c E w e n , 2000).. According to this model. some. people have to m a k e more effort than others to maintain homeostasis.. Neuroticism. (N). is a relatively stable trait that can. be defined. as. the. predisposition to respond with intense emotional reactions to psychological stressors (Lahey, 2009).. In fact, individuals high on N perceive and have more stressors,. respond exaggeratedly to them. (called hyperractivity;. Suls, 2001), and. require. significantly more time to recover (Suls & Martin, 2005). Therefore, w e w o u l d expect that those high on Neuroticism (N) w o u l d normally exhibit higher levels of the stresslinked hormone cortisol, reflecting greater frequency and intensity of H P A stimulation from the psychological domain.. Several studies have tried to explain the relationship between daily cortisol secretion and neuroticism with surprisingly inconsistent results. S o m e f o u n d e d h i g h -.

(70) N associated with higher levels of daily cortisol (AUC; Nater, H o p p m a n n , & Klumb, 2010) and elevated C A R (Portella, Harmer, Flint, C o w e n , & Goodwin, 2005); with less C A R flexibility, w h e n w e e k days and w e e k e n d s are c o m p a r e d (Mikolajczak et al., 2010), and with flatter diurnal cortisol slope, but only in high-N males (Hauner et al., 2008).. Nonetheless, other studies have not found a significant relationship. between N and the C A R (Chan et al., 2007; Hill et al., 2013; Riese et al., 2009; V a n Santen et al., 2011), cortisol slope (Ferguson, 2008), or awakening/evening cortisol (Gerritsen et al., 2009).. S o m e methodological issues might explain these inconsistent results.. First,. differences in d e m o g r a p h i c characteristics of sample populations such as sex and age. S e c o n d , diversity in the scales used to m e a s u r e N. Third, differing statistical power reflecting different samples sizes.. However, crucial for cortisol m e a s u r e m e n t. are factors related to the a d e q u a c y of timing and frequency of salivary cortisol samples along the day, synchronization (or not) of cortisol sampling times in relation to awakening time, n u m b e r of sampling days over which daily levels are averaged to obtain valid "typical" values over time, and finally, a d e q u a c y of procedures to ensure participants strict adherence to protocol in relation to time sampling, w h i c h. is. essential if saliva collection is carried out by participants.. T h e data presented here w e r e obtained from a large research project studying individual. differences. students.. In this study, w e have applied sufficient methodological rigor to achieve. valid. results. regarding. and. various. expected. interventions. associations. on. diurnal. between. cortisol. N and. profiles. diurnal. of. cortisol. secretion. W e w a n t e d to demonstrate replicability of effects over time, and given its pronounced diurnal cycle, w e utilized objective checks on the timings of all cortisol samples.. Therefore,. over four year. cohorts, w e. recruited. extreme. N. score.

Figure

Figure 1. Representation of a hierarchical  m o d e l of personality  organization.  A d a p t e d from &#34;Hierarchical organization of personality  and prediction of behavior,&#34; by S
Figure 2. Illustrates the physiological  c a s c a d e involved in the  hypothalamic-pituitary-adrenal (HPA) axis  a n d the regulation  f e e d b a c k after the cortisol secretion
Figure 3. Characteristic of the cortisol diurnal profile during 12hs  period  w h e r e the Cortisol  A w a k e n i n g  R e s p o n s e (CAR) is  represented,  b e t w e e n 0h (wake-up) and first  4 5 minutes (0.75h) after  a w a k e n i n g
Figure 4.  T i m e  c o u r s e of an artificial dataset with six  m e a s u r e m e n t s ;  the triangles  a n d rectangles illustrate the composition of the area  under the curve (AUC)
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