Neuropsychological slowness in obsessive-compulsive patients. Is it confined to tests involving the fronto-subcortical systems?

Background: Although it is acknowledged that obsessive-compulsive (OC) patients may be slower than healthy controls in performing neuropsychological tests, speed has usually been treated as a confounding variable. It is possible, however, that the slower performance of OC patients is itself the result of a dysfunction of specific neural circuits (in particular of fronto-subcortical systems).

Method: A neuropsychological battery including tests sensitive to fronto- and temporo-subcortical dysfunction was administered to a group of OC patients and a group of healthy controls. Each test provided independent indices of accuracy and speed.

Results: OC patients were significantly slower than controls only when performing tasks involving the fronto-subcortical systems, whereas they did not differ from controls with respect to accuracy indices.

Conclusion: It may be that neuropsychological slowness of OC patients is not merely an epiphenomenon of meticulous concern for correct test execution or intrusion of obsessive thoughts, but reflects the dysfunction of fronto-subcortical systems.