(HealthDay News) – Patients with Alzheimer’s disease and psychosis or agitation-aggression who initially respond to antipsychotic drugs are more likely to relapse if treatment is discontinued, according to a study published in the Oct. 18 issue of the New England Journal of Medicine.

Davangere P. Devanand, M.D., from Columbia University in New York City, and colleagues randomly assigned 110 patients with Alzheimer’s disease and psychosis or agitation-aggression who had responded to 16 weeks of risperidone treatment to continued risperidone therapy for 32 weeks, risperidone therapy for 16 weeks followed by placebo for 16 weeks, or placebo for 32 weeks.

The researchers found that the relapse rate in the first 16 weeks after randomization was significantly higher in the placebo-only group (60 versus 33 percent for both risperidone groups; hazard ratio with placebo, 1.94). During the next 16 weeks, the relapse rate was also significantly higher in the group that switched to placebo compared with the group that continued risperidone treatment (48 versus 15 percent; hazard ratio, 4.88).

“Our findings suggest that patients with psychosis or agitation-aggression who have a sustained response to antipsychotic treatment for four to eight months have a significantly increased risk of relapse for at least four months after discontinuation, and this finding should be weighed against the risk of adverse effects with continued antipsychotic treatment,” Devanand and colleagues conclude.

Several authors disclosed financial ties to pharmaceutical companies, including Janssen, which manufactures risperidone and provided the medication and placebo for the study.

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