Psychopharmacologic Data. The treatment of OC symptoms in schizophrenia has been only minimally studied. Although the current data about the treatment of OC symptoms in schizophrenia come from only one controlled clinical trial (Berman et al., 1995b) and several open trials (Kurokawa and Tanino, 1997; Zohar et al., 1993), the current evidence indicates that anti-obsessional agents improve OC symptoms in schizophrenia in much the same way as they improve OC symptoms in OCD.
Novel antipsychotics, which may be helpful adjuvant agents in the treatment of severe OCD with psychotic features (McDougle et al., 2000) have been reported to precipitate the emergence or exacerbation of OC in some patients with schizophrenia. It has been hypothesized that the worsening of OC symptoms may be a consequence of the novel antipsychotics' serotonin activity (Berman et al., 1999) and that patients with schizophrenia who experience OC symptoms may respond differently to treatment than patients without OC symptoms. Psychopharmacologic data seem to indicate that OC symptoms in schizophrenia may represent a cluster of symptoms separate from psychosis per se.
Progress in neuropsychology also has helped the formulation of new theories about neuroanatomical substrates of psychiatric symptoms. We conducted a neurocognitive study in a group of stable patients with schizophrenia to determine whether OC symptoms in these patients were similar to obsessions and compulsions in patients with OCD (Berman et al., 1998). We found that the severity of OC symptoms predicted poor performance on exactly the same cognitive tests that indicated deficits in patients with OCD who did not have schizophrenia. In addition, the severity of OC symptoms was correlated with poor performance on areas of cognition that were shown to be affected in OCD (e.g., perseverative errors and answers on the Wisconsin Card Sorting Task [WCST] and delayed visual memory). These findings support the hypothesis that OC symptoms in schizophrenia share similar etiologic substrates as obsessions and compulsions in patients with OCD.OC Symptoms
The prevalence of OC symptoms in patients with schizophrenia (20% to 50%) (Berman et al., 1998) is considerably higher than that of OCD in the general population (3%) (Karno et al., 1988), which may lead to the speculation that this association is more than just simple comorbidity. In our neurocognitive study, the patients were correctly classified into either the OC or non-OC group (over 80%), depending on their cognitive performance (Berman et al., 1998). This finding could suggest that there may be two distinct subtypes of schizophrenia based on the presence or absence of OC symptoms.
Insights about the significance of such a high prevalence of OC symptoms in schizophrenia may also be derived from developmental studies in animals. Animal studies have suggested that experimentally induced lesions in the dopamine(Drug information on dopamine) system, largely implicated in the pathobiology of schizophrenia, produce marked alterations in the serotonin system involved in the pathobiology of OCD (Breese et al., 1984; Jackson et al., 1988). It is possible that during early developmental states, patients with schizophrenia suffer alterations in both the dopamine and serotonin systems that, later in life, may clinically manifest themselves through the presence of OCD-like symptoms. In addition, it is possible that patients with schizophrenia and OC symptoms may have suffered different developmental anomalies than those patients without OC symptoms (Berman et al., 1999). At this time, however, we do not have sufficient data to determine whether OCD-like symptoms in schizophrenia are expressions of comorbid OCD or if they are manifestations of different illness subtypes altogether. Genetic, brain-imaging and family studies may help us better understand the significance of the association between OC symptoms and schizophrenia.
Nevertheless, based on the current evidence, we may conclude that OC symptoms are frequently seen in patients with schizophrenia and respond to treatment with anti-obsessional agents, rather than antipsychotics. Clinicians should pay increased attention to the OC phenomenon in the psychotic patient, especially since the differentiation between OC symptoms and psychosis can frequently represent a real challenge.