(EN) Methods of treating or suppressing Pervasive Developmental Disorders (PDDs) including; Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and PDD-Not Otherwise Specified (PDD-NOS) comprising administering to a subject in need thereof a therapeutically effective amount of a tocotrienol, a tocotrienol ester, a tocotrienol ether, a tocotrienol enriched extract or mixtures thereof.