The role of habit in maintaining binge/purge behaviors: An ecological momentary assessment study

Habitual behavioural control moderates the relation between daily perceived stress and purging

OBJECTIVE

Evidence suggests that interpersonal stress plays a role in maintaining binge eating and purging (e.g., self-induced vomiting, misuse of laxatives). Stress is especially likely to promote engagement in maladaptive behaviour if the behaviour is habitual; therefore, individuals whose binge eating and/or purging are habitual may be particularly likely to engage in these behaviours in the context of interpersonal stress. We aimed to investigate this hypothesis in a sample of women with binge eating and/or purging using ecological momentary assessment (EMA).

METHOD

Women (N = 81) with binge-eating and/or purging symptoms completed a self-report measure assessing habit strength of binge eating and purging followed by a 14-day EMA protocol assessing daily perceived interpersonal stress and binge-eating and purging episodes.

RESULTS

Habit strength of purging moderated the within-person effect of interpersonal stress on purging frequency, such that higher daily stress was associated with greater same-day purging frequency when purging was more habitual. Contrary to expectations, the interactive effect of habit strength of binge eating and daily interpersonal stress on same-day binge-eating frequency was non-significant.

CONCLUSIONS

Findings suggest that individuals with habitual purging may be vulnerable to engaging in purging when they are experiencing high levels of interpersonal stress.

A transdiagnostic and translational framework for delineating the neuronal mechanisms of compulsive exercise in anorexia nervosa

OBJECTIVE

The development of novel treatments for anorexia nervosa (AN) requires a detailed understanding of the biological underpinnings of specific, commonly occurring symptoms, including compulsive exercise. There is considerable bio-behavioral overlap between AN and obsessive-compulsive disorder (OCD), therefore it is plausible that similar mechanisms underlie compulsive behavior in both populations. While the association between these conditions is widely acknowledged, defining the shared mechanisms for compulsive behavior in AN and OCD requires a novel approach.

METHODS

We present an argument that a better understanding of the neurobiological mechanisms that underpin compulsive exercise in AN can be achieved in two critical ways. First, by applying a framework of the neuronal control of OCD to exercise behavior in AN, and second, by taking better advantage of the activity-based anorexia (ABA) rodent model to directly test this framework in the context of feeding pathology.

RESULTS

A cross-disciplinary approach that spans preclinical, neuroimaging, and clinical research as well as compulsive neurocircuitry and behavior can advance our understanding of when, why, and how compulsive exercise develops in the context of AN and provide targets for novel treatment strategies.

DISCUSSION

In this article, we (i) link the expression of compulsive behavior in AN and OCD via a transition between goal-directed and habitual behavior, (ii) present disrupted cortico-striatal circuitry as a key substrate for the development of compulsive behavior in both conditions, and (iii) highlight the utility of the ABA rodent model to better understand the mechanisms of compulsive behavior relevant to AN.

PUBLIC SIGNIFICANCE

Individuals with AN who exercise compulsively are at risk of worse health outcomes and have poorer responses to standard treatments. However, when, why, and how compulsive exercise develops in AN remains inadequately understood. Identifying whether the neural circuitry underlying compulsive behavior in OCD also controls hyperactivity in the activity-based anorexia model will aid in the development of novel eating disorder treatment strategies for this high-risk population.