Fragile X syndrome (FXS) is the most common inherited form of developmental disability. FXS
is inherited from the carrier parent, most often the mothers. FXS is associated with severe
interfering behavioral symptoms which include anxiety related symptoms, attention deficit
hyperactivity, and aggressive behaviors. Approximately 25-33% of individuals with FXS also
meet criteria for autistic disorder. The hypothesis of this study is that treatment with
acamprosate will reduce inattention/hyperactivity, language impairment, irritability, social
deficits, and cognitive delay in youth with FXS. The purpose of this study is to investigate
the effectiveness and tolerability of acamprosate in youth with Fragile X Syndrome and to
assess the potential psychophysiological differences between FXS and autism spectrum
disorders.