Background: Atypical antipsychotics decrease irritability in autism. They also affect the cytokine network. Psychological stress, depression, and, possibly, autism spectrum disorder (ASD) are associated with the production of pro-inflammatory cytokines. We sought to determine if risperidone treatment led to changes in plasma cytokine levels.
Methods: Forty-five subjects from an open-label study of risperidone treatment of children and adolescents with ASD, ages 4-18 years, had an analysis of 27 different cytokines at baseline and after 8 weeks of treatment using multiplex assays (Millipore) and read on the Luminex 100(™) platform. We examined changes in each of the cytokine levels in the entire group, and also compared changes in cytokines in responders versus nonresponders.
Results: After 8 weeks of risperidone treatment, 2 of the 27 plasma cytokines showed statistically significant decreases in median levels: Eotaxin (p=0.0003) and monocyte chemoattractant protein-1 (MCP-1) (p=0.0024). Six of the 48 subjects met two criteria for responders to risperidone, and the median values of interleukin (IL)-5 were significantly higher (p=0.005) in the overall responder group than in nonresponders.
Conclusions: Two cytokines, eotaxin and MCP-1, which have previously been identified as abnormally elevated in children with autism, decreased during treatment with risperidone. This suggests a possible mechanism of action of risperidone treatment and a balancing of the immune system in affected subjects in this very preliminary study.