Effect of Aripiprazole on Cognitive Function and Hyperprolactinemia in Patients with Schizophrenia Treated with Risperidone

OBJECTIVE This study aimed to assess the efficacy of aripiprazole for the management of cognitive impairments and hyperprolactinemia in patients with schizophrenia on a stable dose of risperidone. METHODS Thirty-five subjects stabilized on risperidone (3-6 mg/day) for a minimum of 3 months were enrolled in a double-blind, placebo-controlled phase for 12 weeks and an open-label phase for another 12 weeks. Subjects were randomly assigned to receive 10 mg/day aripiprazole (n=17) or placebo (n=18). Over the following 12 weeks, the the aripiprazole group received a flexible dose of aripiprazole while tapering risperidone. At baseline, week 12, and week 24, subjects were evaluated using the Positive and Negative Syndrome Scale (PANSS), Extrapyramidal Syndrome Rating Scale (ESRS), and standardized neuropsychological assessments. Serum prolactin levels were checked at baseline, week 1, week 2, and week 24. RESULTS The mean change in total PANSS and cognitive function test scores between baseline and endpoint were similar in the aripiprazole and placebo groups. Scores on the ESRS and negative subscale of PANSS differed significantly between groups in both phases of the study (p<0.05), indicating a positive effect of aripiprazole. Compared with placebo, aripiprazole significantly reduced mean baseline serum prolactin levels within 1 week (p=0.015). CONCLUSION Adjunctive treatment with and switching to aripiprazole were not associated with improved cognitive function in patients with schizophrenia receiving risperidone; however, aripiprazole treatment decreased negative symptoms and risperidone-induced motor side effects and lowered serum prolactin levels.