Boundary of Anxiety Disorders: Obsessive-Compulsive Disorder and Schizophrenia

Lim, Joon Suk; Kim, Chan Hyung

Abstract

Although obsessive-compulsive disorder (OCD) is recognized as a major psychiatric illness, few studies have investigated obsessive-compulsive symptoms in patients with schizophrenia. Recent increases in dual diagnosis due to changes to the DSMIV diagnostic criteria, findings of obsessive-compulsive symptoms (OCS) after administration of atypical antipsychotics, increased reports of co-occurrence of schizophrenia and OCD have increased the interest in OCS in schizophrenia. The incidence of OCS in patients with schizophrenia is reported to be 3-59%; however, the rate of progression to schizophrenia from OCD is not higher than in the general population. Level of insight, which differentiates obsessions from delusions, can be confounded by the specifier 'with poor insight' in OCD. OCD with schizotypal personality disorder or poor insight differs from pure OCD in that it responds poorly to treatment, has a poor prognosis, leads to deficits in cognitive functioning similar to those observed in schizophrenia, and responds well to low-dose antipsychotics. In the past, it was believed that OCS could prevent or delay the deteriorative course of schizophrenia. However, recent studies have shown that co-occurrence of OCD and schizophrenia increases the severity of symptoms, delays the treatment response, and reduces socio-occupational functions. Schizophrenia and OCD share the same pathophysiology in that both diseases have defects in the fronto-basal functional circuitry of the brain. The use of serotonin and dopamine has been addressed in schizophrenia due to the use of atypical antipsychotics in patients with schizophrenia. The finding of drug-induced OCS suggested that the two diseases share a similar pathogenesis involving neurotransmitters. Further studies are needed to make an exact diagnosis between the two diseases and to determine the common pathophysiology between OCD and schizophrenia.