Clozapine for Substance-Abusing Schizophrenic Patients

To the Editor: Substance abuse, including cocaine, is common among individuals with schizophrenia (1). While effective medications for these dual-diagnosis patients have not been established, atypical antipsychotics may hold promise. Clozapine has been reported to decrease alcohol and cocaine use in chronically psychotic patients (2). Other atypical agents may also be effective in reducing cocaine use as well (unpublished report by J.W. Tsuang et al., 1998). This report describes a patient who stopped abusing drugs when treated with clozapine.

Mr. A’s case, and others that we have treated, suggests that clozapine may reduce substance abuse while decreasing psychotic symptoms in chronically ill schizophrenic patients. Although the reasons are uncertain, a lesser need to self-medicate psychiatric symptoms and greater insight into the negative consequences of drug use are possible explanations. Furthermore, it has been proposed that higher dopamine concentrations and additional serotonergic input are required for psychostimulant-induced euphoria (3). Sole manipulation of the dopamine system to reduce cocaine use has not been effective (3). Using clozapine to block serotonin receptors might reduce cravings and the euphoric effects of cocaine. Additionally, atypical agents are less disruptive to cognitive functions, thus enabling the use of coping skills learned during treatment. We are currently conducting trials to determine whether atypical agents are more effective for dual-diagnosis patients.