psychology, obesity and molecular genetics together.
4. Similarly, it is the first study to attempt to validate a PPI by using OXTR expression as a model system.
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1.2.4. Overview of the remaining chapters
The first four chapters of the thesis provide supporting information for the development of the PPI for weight management, and justification of its structure, design and application.
The remaining six chapters focus on addressing the four main aims of this research through different studies that were conducted over the past three years, and discussing the main findings and overall implications of this research.
Chapter 2 has three main parts. The first one will review the literature on different approaches currently used to treat obesity discussing their effectiveness. Looking through the history of positive psychology and its applications, part two will discuss the effects of positive psychology on physical and mental health problems related to obesity and/or leading towards its development. Part three will explore the principles of genotype-environment interactions in greater detail highlighting the significance of the role of the environment in gene expression.
It will discuss how the application of “-OMICS2” approaches to the study of treatment methodologies in medical and biomedical sciences can aid understanding of the dynamic interactions between genetic variants associated with well-being and genetic variants related to obesity, and how these can be affected by the environment.
Chapter 3 focuses on reviewing the general methodologies used in psychological and biological sciences, which are directly relevant to the current research. The chapter has two main parts: (1) describes quantitative methodology used within psychology to assess effectiveness of novel treatments, (2) describes methodologies of gene-expression analysis
2 “-OMICS” refers to a field of study ending in the neo-suffix “-omics” [from Greek -ωμα (-ōma)], such as genomics, transcriptomics, epigenomics, proteomics, metabolomics or interactomics.
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used within the field of molecular genetics with particular focus on the real-time reverse-transcriptase quantitative polymerase chain reaction (real-time RT-qPCR) used in this research.
Chapter 4 provides information on the theoretical background justifying the structure, design, and development of the PPI for weight management created within the scope of this PhD. It discusses each of the positive psychological themes intentionally selected as the most suitable for use in addressing overweight and obesity, and it provides justification for all exercises used throughout the intervention.
Chapter 5 describes the use and application of bioinformatics approaches used to identify gene networks, which offer functional basics of the complexity of gene and protein, and their interacting partners. Using the network study on genes and proteins, researchers are able to find novel candidate genes based on the assumption that neighbours of a disease-causing gene in a network are more likely to cause either the same or a similar disease. For the purpose of the present research, gene networks will be used to identify whether and how genes involved in positive psychological functioning can be implicated in obesity. That will serve as a basis for creating a model describing potential molecular genetic pathways through which the PPI functions/affects weight loss.
Chapter 6 discusses the first two studies conducted to pilot the present PPI. It reports the results of the two pilot studies, and discusses the major implications of the pilot findings leading to the development of a full randomised controlled trial (RCT). The chapter also provides an overview of the main differences between the two studies, and a detailed explanation and justification of the changes and alterations made for the purpose of the main trial.
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Chapter 7 reports the results obtained in the RCT which was conducted with an immediate intervention group and a wait list control group. Implications of these findings are discussed in terms of well-being, body-image flexibility, depression, anxiety, and weight loss.
Chapter 8 provides a detailed review of the protocols adopted for the RT-qPCR, and results of the OXTR gene expression analyses combining samples from all conducted studies.
It also reports results from psychological analyses that have been conducted after merging all data from all the studies together to enable comparison with the OXTR expression findings.
Chapter 9 provides a detailed summary of all the findings discussing their major implications for both fields, positive psychology and molecular genetics, in terms of addressing overweight and obesity. It addresses limitations of this research, and presents suggestions for future studies.
Chapter 10 is devoted to concluding remarks. Re-visiting the four main aims of this research, the chapter finishes with highlighting the original contributions to knowledge brought by this PhD research.
1.3. Chapter Summary
Until now, there seems to be inconsistent evidence for long-lasting effects or health improvements of any currently applied obesity treatments (Fradkin, Wallander, Elliott, Cuccaro & Schuster, 2016). This suggests that there is a need for development of an alternative treatment approach, which would target the problem of obesity more comprehensively. A large amount of research evidence shows that positive psychology can be successfully applied to comorbidities associated with obesity, such as depression (Layous & Lyubomirsky, 2014; Sin
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& Lyubomirsky, 2009), addiction (Krentzman, 2013), alcohol misuse (Akhtar & Boniwell, 2010), overeating (Bardone-Cone et al., 2012), and binge eating disorder (Pinto-Gouveia et al., 2017). However the role of positive psychology in the reduction of obesity itself remains unexplored. Given the recent debate in molecular genetics on the interactions between genes and environment (Plomin et al., 2013), it may be possible that the gene-environmental interactions play a significant role in the responsiveness of obese or overweight individuals to a particular type of treatment. Some individuals may be more responsive to the treatment than others, depending on their specific genotypes and phenotypes (Beevers et al., 2011).
The aim of this PhD research is to explore whether positive psychology could be used as an alternative or complementary treatment for overweight and obesity, while also identifying potential molecular genetic pathways through which positive psychological stimuli might affect weight loss. Using OXTR expression as a model system, this PhD aims to validate a PPI for weight management, which, if successful, could subsequently serve as an objective method for the validation of other interventions in positive psychology.
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