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Effects of short- and long-term risperidone treatment on prolactin levels in children with autism.

Anderson GM, Scahill L, McCracken JT, McDougle CJ, Aman MG, Tierney E, Arnold LE, Martin A, Katsovich L, Posey DJ, Shah B, Vitiello B

Child Study Center, Yale University School of Medicine, New Haven, Connecticut, USA. george.anderson@yale.edu

BACKGROUND: The effects of short- and long-term risperidone treatment on serum prolactin were assessed in children and adolescents with autism. METHODS: Patients with autism (N = 101, 5-17 years of age) were randomized to an 8-week trial of risperidone or placebo and 63 then took part in a 4-month open-label follow-up phase. Serum samples were obtained at Baseline and Week-8 (N = 78), and at 6-month (N = 43) and 22-month (N = 30) follow-up. Serum prolactin was determined by immunoradiometric assay; dopamine type-2 receptor (DRD2) polymorphisms were genotyped. RESULTS: Baseline prolactin levels were similar in the risperidone (N = 42) and placebo (N = 36) groups (9.3 +/- 7.5 and 9.3 +/- 7.6 ng/ml, respectively). After 8 weeks of risperidone, prolactin increased to 39.0 +/- 19.2 ng/ml, compared with 10.1 +/- 8.8 ng/ml for placebo (p < .0001). Prolactin levels were also significantly increased at 6 months (32.4 +/- 17.8 ng/ml; N = 43, p < .0001) and at 22 months (N = 30, 25.3 +/- 15.6 ng/ml, p < .0001). Prolactin levels were not associated with adverse effects and DRD2 alleles (Taq1A, -141C Ins/Del, C957T) did not significantly influence baseline levels or risperidone-induced increases in prolactin. CONCLUSIONS: Risperidone treatment was associated with two- to four-fold mean increases in serum prolactin in children with autism. Although risperidone-induced increases tended to diminish with time, further research on the consequences of long-term prolactin elevations in children and adolescents is needed.

Published 5 February 2007 in Biol Psychiatry, 61(4): 545-50.
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