To the Editor: In the July 2010 issue of the Journal, Carolyn I. Rodriguez, M.D., Ph.D., et al. (1) presented an interesting case illustrating the complexities of co-occurring psychotic and obsessive-compulsive disorders (OCD). The authors should be commended for their careful review of the differential diagnosis and treatments for a patient presenting with these intertwined symptoms.

In the case study, the patient was found to have manifested obsessive compulsive symptoms prior to his first psychotic episode. Such a presentation is consistent with the results of a meta-analysis we conducted regarding the temporal relationship of OCD and schizophrenia in patients suffering from both disorders (2). Our analysis showed that in patients diagnosed with both disorders, OCD tends to precede schizophrenia by 1 year. While our study did not find this result to be statistically significant, it did nearly reach significance (p=0.066), suggesting the potential for statistical significance in studies with a larger sample size. Clearly, Dr. Rodriguez et al.'s suggestions for longitudinal studies of young people at risk for psychosis or OCD would provide for much needed insight into the epidemiology and clinical phenomenology of cooccurring obsessive compulsive and psychotic symptoms.

In their discussion of the potential adverse drug-drug interactions between clozapine and fluvoxamine, the authors appropriately mentioned cytochrome 3A4. We would like to also mention that cytochrome 1A2 is even more significantly involved in the metabolism of clozapine (3). As a strong inhibitor of cyto-chrome 1A2, combining fluvoxamine with clozapine in patients suffering from both OCD and treatment-resistant schizophrenia may produce serious adverse effects. Further, nicotine in tobacco is an inducer of cytochrome 1A2 and may lead to attenuation of the efficacy of clozapine unless the dose is increased.