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Neurobiological and metabolic mechanisms of binge-eating in anorexia and bulimia nervosa


Type

Thesis

Change log

Authors

Westwater-Wozniak, Margaret  ORCID logo  https://orcid.org/0000-0002-2918-0979

Abstract

Binge-eating is characterised by the recurrent consumption of large amounts of food, which co-occurs with a subjective loss of control over intake. This transdiagnostic syndrome results in significant distress, functional impairment and comorbidity. However, precise characterisation of the physiological and neurobiological mechanisms that give rise to, or maintain, this behaviour is lacking. This thesis integrates observations across metabolic, neural and behavioural levels in women with and without eating disorders, providing novel insights into how perturbations across each strata interact with one another in illness and in health to shape eating behaviour.

In Chapter 1, I review the classification of binge-eating disorders prior to summarising the extant literature on homeostatic and non-homeostatic mechanisms that influence (ab)normal eating behaviour. This introductory chapter also reviews current perspectives on how psychological stress influences disordered eating, outlining the motivation for the multimodal neuroimaging protocol detailed in Chapter 2. Chapter 2 focuses on the specific methodology of this neuroimaging study, which examined the impact of acute, psychological stress on gut hormones, endocrine responses, and inhibitory control in women acutely ill with the binge-eating and purging subtype of anorexia nervosa, bulimia nervosa and matched controls. Chapters 3 through 5 report the results of this study.

Chapter 3 focuses on findings of dissociable hormonal responses to stress in anorexia and bulimia nervosa, presenting novel evidence that links acute changes in mental state to altered gut hormone signalling in anorexia nervosa. Chapter 4 is dedicated to the functional magnetic resonance imaging arm of the protocol, which rigorously examined the impact of diagnosis and induced stress on two forms of response inhibition: proactive and reactive control. Chapter 5 provides insight into associations between peripheral metabolic markers and neural integrity of the cerebral cortex in patients and controls.

Finally, Chapter 6 provides a brief summary, discusses the implications of these findings and presents some ongoing and future research that extends this original work.

In summary, this thesis represents, to my knowledge, the first attempt to generate a multi-level framework for understanding the physiological and psychological mechanisms of illnesses characterised by binge-eating. Findings identify important metabolic and neurobiological distinctions between two eating disorders with shared symptomatology, demonstrating the need for, and value in, integrative models of mental illness.

Description

Date

2020-09-01

Advisors

Fletcher, Paul
Ziauddeen, Hisham

Keywords

eating disorders, acute stress, fMRI, cognitive control, inhibitory control, ghrelin, magnetic resonance spectroscopy

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsorship
Wellcome Trust (206368/Z/17/Z)
Cambridge International Trust; NIH Oxford Cambridge Scholars Program