Understanding the nature of association between anxiety disorders and anorexia nervosa
: a triangulation approach

  • E C Lloyd

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Anorexia nervosa (AN) is a psychiatric disorder that has severe impacts on physical and mental health. More effective prevention interventions may reduce the burden of AN, however this rests on targeting factors with known causal effects on AN development. This thesis aims to further knowledge of the nature of association between anxiety disorders and AN, to inform the utility of addressing anxiety disorder pathology for AN prevention.

Four studies were completed. Study 1 comprised a systematic review of investigations probing the longitudinal association between anxiety and subsequent AN onset; findings indicated that anxiety disorder pathology generally, rather than that specific to a given diagnosis, may be relevant to AN. In Study 2 the association of anxiety disorder presence with later AN behaviour was assessed in a large adolescent population cohort; a positive association was supported. Study 3 assessed the association of anxiety disorder presence, and the worry central to anxiety disorders, with AN. Two methods were used: longitudinal data analysis; and Mendelian randomization (MR), a framework for causal inference. Evidence provided strong support for a prospective association between anxiety disorders and AN, yet suggested only worry (i.e. not anxiety disorders more broadly) causally influenced AN risk. Study 4 assessed the causal influence of worry, depressed affect and neuroticism (of which worry and depressed affect are manifestations) on anxiety disorders and AN using MR. Statistical evidence supported neuroticism causally influencing both anxiety disorders and AN, with worry the specific component relevant to AN.

Outcomes support a causal role of worry in AN development, and suggest that the anxiety disorder and AN association is to some extent explained by the two sharing causal risk factors. The mechanism by which worry translates into AN risk requires elucidation, however findings indicate addressing processes underlying worry may improve the efficacy of AN prevention efforts.
Date of Award28 Nov 2019
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorCharlie E M Foster (Supervisor), Bas Verplanken (Supervisor), Anne M Haase (Supervisor) & Jeff Brunstrom (Supervisor)

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