Physical exercise-related endophenotypes in anorexia nervosa

Background The persistence of physical exercise in anorexia nervosa (AN) despite underweight and its maintaining factors are poorly understood. The aim of this study was to explore the attitudes toward physical exercise and its effects on emotions, cognitive functioning, and body image perception in patients with AN, and to search for exercise-related endophenotypes of the pathology. Methods Physical exercise dependence, quantity, and dysregulation were assessed by the Exercise Dependence Scale (EDS), the Godin Leisure Time Exercise Questionnaire (GLTEQ) and a standardized effort test in 88 patients with AN, 30 unaffected relatives and 89 healthy controls. Changes in positive and negative affect, cognitive rigidity, and body image distortion were measured before and after the effort test in the three groups. Results Patients with AN had higher scores on the EDS and the GLTEQ and used more effort in the standardized effort test. These three measures of physical exercise correlated with negative emotions at baseline. After the effort test, patients with AN had marked emotional improvement, a moderate increase in body image distortion and a small increase in cognitive rigidity compared to HC. Unaffected relatives also had a significant postexercise increase of positive emotion. Discussion The mood-related drive for physical exercise has the characteristics of an endophenotype of the disorder. Excessive and driven physical exercise may be state-associated features of AN, driven by the positive effect on emotional wellbeing.