Perseveration and not strategic deficits underlie delayed alternation impairment in obsessive-compulsive disorder (OCD)

The claim that the prefrontal cortex, particularly its orbito-frontal part, is involved in obsessive-compulsive disorder (OCD) is based upon evidence from neuroimaging as well as behavioral studies. Studies have repeatedly suggested problems with delayed alternation learning in OCD. an executive dysfunction that presumably involves the orbito-frontal cortex. However. it is unclear whether such impairment stems from perseveration or strategic deficits as these aspects are intertwined in the original task. In the present study, 36 OCD and 16 healthy controls underwent a variant of the delayed alternation task involving three response options instead of two as in the original task. This modification enabled us to separate perseveration errors (i.e., the participant incorrectly. chooses the same response option as before) from shift errors (i.e., the decision is switched to an incorrect response alternative). We found that patients with OCD committed significantly more perseveration errors following previously valid response options, whereas perseveration for previously invalid responses and shift errors did not distinguish groups. Group differences were not accounted for by comorbid depression and may be linked to the pathogenesis of OCD. (c) 2008 Elsevier Ireland Ltd. All rights reserved.