Anorexia nervosa (AN) patients show remarkably rigid control over eating and exhibit persistent and obsessive temperament traits. Neuropsychological studies have shown minor impairments in cognitive flexibility in AN patients. The aim of the present study was to investigate alterations of the functional neuroanatomy in AN patients performing a cognitive flexibility task.

Thirteen female subjects aged 18 to 26 years with chronic AN (8 with the purging subtype) and 15 age-matched healthy female controls (HC) underwent functional magnetic resonance imaging while performing a reactive flexibility task. In an event related paradigm, participants had to respond with a different button press to infrequent target stimuli embedded in the prepotent presentation of standard stimuli. The performance to the task was quantified as reaction time and number of correct trials.

On behavioral level, AN patients and the HC group showed a similar performance (reaction times, number of correct trials) in the reactive flexibility task. During correct behavioral shifts, the AN patients compared to the HC group showed decreased activation of the bilateral thalamus, ventral anterior cingulate gyrus (ACC), ventral insula, dorsolateral prefrontal (DLPFC), premotor cortex, visual stream and cerebellum (p uncorr. < .001).

AN patients show an impaired activation in thalamo-(striato)-cortical loops involved in response selection and behavioral shift. These findings support from a neurobiological perspective a more generalized cognitive rigidity in AN, that is not restricted to food, weight and shape.