Anxiety matters: a pilot lab study into food, weight, and virtual body exposure in anorexia nervosa

Abstract

Anxiety is a core characteristic of anorexia nervosa and a potential target of exposure therapy, which requires a profound understanding of the patients’ fears in order to be successful. The knowledge about fears in anorexia nervosa that should be targeted during exposure therapy can be enriched by laboratory research to the precise emotional and behavioral responses of anorexia nervosa patients when they are exposed to disorder relevant fear stimuli. In the laboratory, patients with anorexia nervosa (n = 15) and healthy controls (n = 51) were exposed to 1. their own body weight and a 10% higher body weight on the scale, 2. a standardized lab breakfast, and 3. five virtual bodies with different BMIs ranging from extreme underweight to lower healthy weight. The participants emotional (anxiety, disgust, satisfaction, acceptance) and behavioral responses (calorie consumption) were assessed. Patients with anorexia nervosa but not the healthy controls then received an intensive exposure treatment (~ 30 individual exposure sessions) targeting their individual fears, next to standard care. After the exposure treatment, it was investigated whether the patients’ responses to the laboratory tasks changed. Across all tasks, the patients reported more anxiety than healthy controls. The patients also consumed less calories during the breakfast and accepted the different body weights on the scale less than healthy controls. During the virtual body exposure, the patients’ emotional responses did not differ per avatar but they reacted more negatively towards avatars with healthier weights than did healthy controls. After the exposure treatment, the patients reported less fears and they consumed more calories while their BMIs had increased. They were also more accepting of healthier weights. Exposure to food-, body- and weight-related stimuli in the laboratory induces emotional reactions in patients with anorexia nervosa that are informative for the identification of exposure therapy treatment targets. In addition, exposure therapy targeting individual fears in patients with anorexia nervosa led to symptom reduction and is a promising intervention for the treatment of anorectic fears, though more research is needed to optimize its efficacy. Anxiety is an important characteristic of anorexia nervosa and a target of exposure therapy. Recent research revealed the variety of fears and other emotions (e.g. disgust) that patients with anorexia nervosa display, and that could be addressed in exposure therapy. More nuanced knowledge about potential treatment targets could be derived from experimental research which has so far mainly focused on the fear of food. We aimed to fill this gap by experimentally studying the behavioral and emotional responses of patients with anorexia nervosa (n = 15) and healthy controls (n = 51) when exposed to food-, body-, and weight-related stimuli in the laboratory, and then also tested whether the patients’ responses changed after they received an intensive exposure treatment. Patients were found to be more anxious about food and weight related stimuli, consumed fewer calories, and reacted more negatively when they imagined that virtual bodies of different weights were theirs, than did healthy controls. After the exposure treatment, patients reported less fears and they consumed more calories, while their BMIs had increased. They were also more accepting of healthier body weights. Exposure therapy is a promising intervention for the treatment of anorectic fears but more research is needed to optimize its effectiveness.