Anorexia nervosa with excessive exercise: a phenotype with close links to obsessive-compulsive disorder

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) are highly comorbid, and appear to share a common neurophysiological dysfunction that contributes to the obsessional thoughts and compulsive behaviours seen in both disorders. Obsessive-compulsive personality (OCP) traits are also important risk factors for AN. Since excessive exercise has also been associated with greater obsessionality, we hypothesised that AN patients with a hyperactive behavioural profile represent a phenotype more closely linked to OCD than their non-exercising counterparts. We examined prospectively 50 female AN-Restrictor patients whom we classified as "excessive" or "non-excessive" based on their exercise status i) at admission and ii) over the lifetime of their illness. Validated measures of OCD symptoms and OCP traits were obtained at admission and after refeeding at discharge. On both classification methods, excessive exercisers had greater OCD symptoms and OCP traits than the non-excessive group, but did not differ on body mass index. OCD symptoms, but not OCP traits, decreased between admission and discharge. Findings support our prediction that AN patients with excessive physical activity constitute a subtype of the disorder with strong links to OCD. Indeed, this phenotype may be a culture-bound variant of OCD.