Obsessive-compulsive disorder among schizophrenic patients : An exploratory study using functional magnetic resonance imaging data

Despite the growing research on the etiology of obsessive-compulsive disorder (OCD), and schizophrenia, the clinical distinction between the two disorders is not clearly understood. In the present investigation, we sought to better understand the relationship between OCD and psychotic disorders by examining functional magnetic resonance imaging (fMRI) data from a group of schizophrenic patients with varying degrees of OCD symptomatology, based on results of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the National Institute of Mental Health (NIMH) rating scales of OCD. While subjects performed a cognitive challenge paradigm that included a verbal fluency task, activation data from the left dorsolateral prefrontal cortex were collected and analyzed. We hypothesized that the fMRI signal patterns in schizophrenic patients with high levels of OCD symptomatology would differ from that of schizophrenic patients with a low level of OCD. For the group as a whole, no significant relationship was found for scores of either rating scale and fMRI signal change; however, a significant association was found for a subgroup of patients. For these schizophrenics, there was a negative relationship between OCD symptomatology and activation of the left dorsolateral prefrontal cortex. These results support the suggestion of several researchers that a relationship between OCD severity and neurophysiological activity exists in schizophrenia.