Gender bias for PDD is significant. Autism and PDD NOS may affect boys up to 5 times more often than girls. In Asperger syndrome, boys may be affected 10 times more often than girls. Rett syndrome and childhood disintegrative disorder also usually are apparent by age 3 years. Children with PDD often exhibit no physical findings.
Seizures are the most frequent comorbidity.
Results can be diagnostic for children with Landau-Kleffner syndrome because seizure activity in the brain speech centers often causes this disorder. In older children, testing may help distinguish PDD NOS from a mood disorder, early presentation of schizophrenia, or schizotypal personality disorder. Testing may identify verbal and nonverbal learning disabilities. Currently, insufficient consensus exists to recommend practice guidelines for medication use in PDD itself. Thorough medical evaluation is warranted before considering psychiatric hospitalization.