Caffeine and schizophrenia.

Although the database is small and not completely consistent, it appears that patients with schizophrenia have high caffeine intakes. The reasons are unclear. In nonhumans, caffeine enhances the effects of dopamine, which might be expected to worsen positive symptoms and improve negative symptoms of schizophrenia and worsen tardive dyskinesia. Eliminating caffeine among patients with schizophrenia does not appear to make them better or worse. Acute intake of large amounts of caffeine may increase psychoses and hostility. However, those who chronically use large amounts of caffeine may develop enough tolerance that these adverse effects do not occur, but whether this conjecture is true has not been tested. Interestingly, persons with schizophrenia do not develop anxiety at high doses of caffeine. Although there was initial concern that caffeine might inactivate liquid doses of neuroleptics, the clinical significance of this concern is unclear. On the other hand, caffeine might increase the level of clozapine, and more research in this area is needed.