Cognitive deficits as an endophenotype for anorexia nervosa: an accepted fact or a need for re-examination?

OBJECTIVE: To investigate whether impaired set shifting and weak central coherence represent state or trait characteristics and, therefore, candidate endophenotypes of anorexia nervosa (AN).

METHOD: Forty-nine individuals with lifetime AN (24 acutely unwell, 10 weight recovered, and 15 fully recovered) and 43 healthy controls completed the Wisconsin Card Sorting Test (WCST), the Matching Familiar Figures Test, and the Rey Complex Figure Task measuring cognitive flexibility, local processing, and global processing, respectively. Participants also completed questionnaires assessing eating disorder, anxiety and depressive symptoms, obsessional traits, interpersonal functioning, and quality of life. Body mass index was calculated from height and weight measurements.

RESULTS: Participants with lifetime AN demonstrated poorer set shifting ability than healthy controls as evidenced by a greater number of perseverative errors on the WCST. When participants were grouped according to illness status, only those in the two recovered groups demonstrated poorer set shifting ability than healthy controls while patients with acute AN performed comparably to all other groups. There were no significant differences between groups on measures of local and global processing. No relationship was found between specific clinical features of AN and cognitive performance.

DISCUSSION: The results of this study are consistent with a global trend toward set shifting difficulties in patients with AN but do not support weak central coherence as a candidate endophenotype for AN. These findings have clinical implications in terms of treatment selection and planning, particularly in relation to the use of cognitive remediation therapy with patients with AN.