Methylphenidate challenge as a predictor of relapse in schizophrenia.

Although neuroleptics are the major treatment for schizophrenia, there are no effective measures to determine the appropriate or necessary length of neuroleptic maintenance. To test the ability of a psychostimulant challenge to predict relapse following neuroleptic withdrawal, the authors administered methylphenidate and placebo infusions to 11 stable schizophrenic outpatients who had been on a neuroleptic maintenance regimen for at least 6 months. Patients withdrawn from neuroleptics were followed until relapse. All three patients with a positive response to methylphenidate challenge relapsed in 1 to 7 weeks; one of seven negative responders relapsed at week 21. Differences in relapse rates (p = .033) and survival time (p = .005) between negative and positive responders were significant.