Phenotypic psychiatric characterization of children with Williams syndrome and response of those with ADHD to methylphenidate treatment.

Williams syndrome (WS) is associated with cognitive deficits, special behavioral phenotype, and high rates of psychiatric disorders. The aims of the present study were: (1) To compare the rates of psychiatric disorders and repetitive behaviors in children with WS to children with idiopathic developmental disability (DDs); (2) To longitudinally assess the change in psychiatric disorders during adolescence in WS; (3) To assess retrospectively the effectiveness and safety of methylphenidate (MPH) treatment in WS children with ADHD. The study consisted of a cohort of 38 children and adolescents (age 13.