Noyos Cascara o Croning Generalidades

Malzberg’s paper in 1937"^^ is commonly cited as the first paper to highlight the risk of heart disease in patients with depression, and the concept that sadness leads to ill-health, and is particularly associated with the heart, has been in literature in its widest sense for many centuries. Malzberg’s paper was an early example o f what is now a large body of work assessing the mortality rates o f psychiatric patients. These studies were initially on institutionalised patients, were small and often relied on standardised mortality rates as a comparison group and hence were poorly adjusted. Later studies have used out-patient samples. A range o f psychiatric conditions has been considered. Although several had indicated that heart disease appeared to be more common in depressed patients'^*'^^ this was sometimes confused with issues o f treatment^^ and the toxicity o f anti-depressant therapy. The effect size o f depressive illness on CHD was usually poorly quantified. Others, although finding an increased mortality, found no evidence that CHD deaths were specifically increased^^'^^. Anxiety disorders have also been examined. Some have reported increased cardiovascular deaths particularly in panic disorder^^’ whilst others found no increase in cardiovascular mortality^^’ Increased mortality is not restricted to affective disorders. It has also been shown in schizophrenics^®. Most o f the psychiatric studies were not designed to study CHD, lacked power and are probably best considered as hypothesis-generating studies.

Alongside this work on psychiatric patients, other investigators were working on the role o f psychosocial influences in the development o f coronary heart disease. Interest was initially in personality as a predictor o f CHD. Ostfeld demonstrated that personality, including the K scale on MMPI, a measure o f neuroticism, was not related to objective measures o f CHD such as myocardial infarction®L Recent reviews have also reported that neuroticism is not related to CHD endpoints, but may lead to an increase in symptom reporting®^. Following positive reports from the Western Collaborative Groups’ Study and the Framingham S t u d y ® ^ ’ ®^, attention was focused on the Type A behaviour pattern (TABP). Subsequent reports did not confirm the early findings and hostility, a component

o f TABP, was considered as the aetiological factor. Recent reviews o f hostility as an aetiological risk factor for CHD have been divided as to its importance and certainly several large studies have not been not supportive^^’ Barefoot has published two small, strongly positive studies^^’ using the Cook -M edley scale^^, which is derived from the MMPI. He demonstrated that, within the whole questionnaire, the subscales o f hostile affect and attribution were related to the incidence of myocardial infarction^^.

In general, the psychological tests used in this psychosocial literature were not designed to measure depressive illness, so that the results could not readily be compared to the clinical diagnoses used in the psychiatric studies. Personality measures, such as the D subscale of M M Pf^, were often used and there were important negatives^\ However, it can be argued the current scientific interest in the relationship between CHD and psychological distress originated in 1987, with Booth-Kewley and Friedman’s review o f the psychological predictors o f heart disease^’. Prior to this, neither studies o f the physical health of psychiatric patients nor community based studies of the psychological predictors o f heart disease had particularly focused on the distress/heart disease link. The review aimed to assess the importance o f TABP in the aetiology of CHD, but showed that the association between measures o f depression and heart disease was larger than that for Type A scales. This conclusion was somewhat unexpected and acted as an impetus to further research. The review also found a weaker association between anxiety and heart disease, and suggested that further work was needed.

In 1993, Anda published a large well-designed study and showed an association between depressive symptoms, measured on the General Well-Being Schedule, and future CHD^^. Since then, many studies on depression have been published and much of data discussed in this review focuses on depression rather than anxiety or more general distress. The categories o f studies included in the review are summarised below.

Depression as an aetiological risk factor

At least 24 cohort studies have considered depressive symptoms as a risk factor for future CHD events^’’ In comprehensive reviews, Kuper et al considered 22 o f these papers^^’ O f these eight were negative^*’ four moderately positive, with relative risks of

than The remaining studies reported that the effect varied by type of event^^"^% length or severity of depression^^’ or gender^'^.

Most recent reviews accept depression as a risk factor for CHD, although there is still considerable confusion over key issues^^'^^. Others remain cautious about the independence o f depression from underlying personality c o n s t r u c t s T w o recent, small meta-analyses estimated the pooled relative risk o f future CHD associated with depression as 1.40 [95% Cl 1.3-1.6]*®* and 1.64 [1.29-2.08]^^l

Anxietv as an aetiological risk factor

There are fewer aetiological studies on anxiety. Eight aetiological cohort studies were identified by Kuper et al, and the results are rather confused. Two were positive for a n g i n a ' a n d two showed an association between phobic anxiety and fatal CHD, particularly sudden cardiac death^^’ A later study from Northwick Park, with follow-up extended to 20 years, was negative for phobic anxiety but positive for obsessional neurosis and somatic complaints*^. Two studies using more generalised anxiety measures were significant in unadjusted analyses only^"'' Kubzansky showed an association between worries about social conditions and CHD, but this was not adjusted for social class"^^. Reviews are mixed with some supportive o f a link'^* and others more guarded^^.

Prognostic studies

Although not directly relevant to the aetiological focus o f this thesis, a large number of papers have examined the role o f anxiety or depressive symptoms in the prognosis of CHD. Interest in the psychological influences on CHD recovery was initially concentrated on social s u p p o r t b u t now a large body o f work exists investigating the role of depressive symptoms in the prognosis o f established CHD"^"'^' . Kuper et al^^ reviewed 34 studies o f which 16 were negative, 7 moderately supportive and 11 strongly supportive. Although the proportion o f positive findings does not differ between the aetiological and prognostic studies, the effect sizes are larger in the prognostic studies. Anxiety and generalized distress have also been examined as prognostic factors, often in the same studies as depression O f 18 studies identified by Kuper et al, half were negative, four showed strong and five moderate support for an association.

This prognostic work is clearly relevant to a discussion o f the second acceleration model, with depression and distress symptoms leading to a progression o f established disease, but it may also be important in identifying potential mediating pathways for other models.

Other work included

Work examining related psychological constructs, such as vital exhaustion, hostility or hopelessness, either as predictors o f future CHD or in prognostic studies, was included where it contributed to the argument concerning psychological distress and CHD.

II.2.2 Measurement instruments, definitions used for distress, anxiety, depressive