Serotonin and dopamine antagonism in obsessive-compulsive disorder: Effectof atypical antipsychotic drugs

Background: Previous reports suggest that some atypical antipsychotics may have obsessogenic as well as antiobsessional effects. Given their higher af finity far serotonin 5HT(2) receptors than dopamine D-2 receptors, it has b een speculated that atypical antipsychotics may induce obsessive-compulsive (OC) symptoms, even at low doses, due to high 5HT(2) antagonism, whereas i mprovement in OC symptoms is thought to occur only at high doses due to hig h D-2 antagonism. Method: In this open case series, the dose-response relat ionship of atypical antipsychotic augmentation in the treatment of obsessiv e compulsive disorder (OCD), and the dose-severity relationship in atypical anti psychotic-induced OC symptoms were examined. Three patients were iden tified who had either refractory OCD or OC symptoms following administratio n of atypical antipsychotics such as olanzapine and risperidone. Results: C ase 1:A linear dose-response relationship between increasing doses of olanz apine and improvement in OC symptoms was observed in an OCD patient resista nt to 5-HT reuptake inhibitors. 2: OC symptoms induced by low doses of risp eridone (1 mg) were reversed by increasing the doses of risperidone (3 mg) in a bipolar disorder patient suggesting an inverse dose-severity relations hip. 3: No inverse dose-severity relationship was noted between olanzapine induced OC symptoms and its dosage in an asymptomatic OCD patient. Tretment -emergence OC symptoms responded to increasing the doses of maintanance clo mipramine treatment. Conclusions: Controlled studies are needed to investig ate the dose-response or dose-severity relationships between OCD and atypic al antipsychotics.