Recent studies suggest that serotonin reuptake inhibitors are helpful in at least some symptoms of autism. Inositol is a precursor of the second messenger for some serotonin receptors, and has been reported effective in depression, panic disorder and obsessive-compulsive disorder. However a controlled double-blind crossover trial of inositol 200 mg/kg per day showed no benefit on 9 children with autism. Since biochemical studies could evaluate inositol in children already receiving serotonin reuptake inhibitors.