Methods of treating or suppressing pervasive developmental disorders (PDDs)including; autistic disorder,Asperg-er's syndrome, childhood disintegrative disorder (CDD), Rett'sdisorder, and PDD-not otherwise specified (PDD-NOS) oratten-tion deficit/hyperactivity disorder (ADHD) comprising administering to asubject in need thereof a therapeutically effectiveamount of one or more compounds as disclosed herein.