CLOZAPINE REDUCES WATER-DRINKING BEHAVIOR IN SCHIZOPHRENIC-PATIENTS WITH POLYDIPSIA

Disordered water balance, or polydipsia, is an underassessed and under reported phenomenon present in the severely psychiatrically disabled p opulation. Prevalence rates for polydipsia range from 6.2 to 20%. We f ollowed up five male patients (mean age 43) with chronic schizophrenia who met the Kane criteria for being treatment nonresponders and who, in addition, had marked polydipsia. Three patients had previously rece ived medical care for hyponatremia and had to be placed on fluid restr iction when admitted to the hospital. AU patients exhibited polydipsia despite high doses of typical antipsychotic drugs. Each patient was t reated openly with clozapine (range 450-800 mg/day) for at least 6 mon ths. In each case, there was a decline in the Brief Psychiatric Rating Scale score (preclozapine mean, 63; post-clozapine mean, 46), and a m arked reduction in fluid-seeking behavior. All fluid restrictions coul d be lifted, and the patients were discharged from the hospital. Durin g a mean follow-up period of 17 months, during which patients were eva luated weekly, polydipsic behavior that required intervention had not been noted. We conclude that clozapine may be a highly effective treat ment for polydipsia in patients with treatment-refractory schizophreni a. Future studies may aim to delineate neurobiologic mechanisms.