Background: Several lines of research suggest that prefrontal cortex dysfunctions observed in obsessive compulsive disorder (OCD) and schizophrenia (SKZ) are linked to two partially independent neuroanatomic systems: the ventromedial prefrontal cortex and the dorsolateral prefrontal cortex, with different neuroanatomic connections, including the striatum. The primary aim of this study was to test this hypothesis using a double dissociation study of neuropsychological tasks performance of the dorsolateral prefrontal cortex and ventromedial prefrontal cortex.
Methods: We administered the Wisconsin Card Sorting Test, the Gambling Task, and the four-disk version of the Tower of Hanoi to 110 SKZ and 67 OCD patients and 56 control subjects.
Results: A clear double dissociation of Wisconsin Card Sorting Test and Gambling Task performances was found, with SKZ patients performing the Wisconsin Card Sorting test significantly worse than OCD patients and control subjects and OCD patients performing the Gambling Task significantly worse than SKZ and control subjects. Both SKZ and OCD patients performed the Tower of Hanoi significantly worse than control subjects.
Conclusions: Results from our double dissociation study confirm the hypothesis of involvement of different frontal lobe subsystems within basal-corticofrontal circuits function in SKZ and OCD.