Autism and epilepsy: cause, consequence, comorbidity, or coincidence?

Autism is associated with epilepsy in early childhood, with evidence suggesting that individuals with both autism and more severe cognitive impairment are at higher risk. However, the incidence of an abnormal electroencephalogram and/or epilepsy in the full range of pervasive developmental disorders (PDDs) is not well defined. This naturalistic study addresses the incidence of epilepsy and electroencephalographic abnormalities in children with PDDs. The clinical history and electroencephalograms of 56 children diagnosed with PDD-not otherwise specified, autism, or Asperger syndrome were retrospectively reviewed. Forty percent of children with autism were diagnosed with epilepsy. Abnormal electroencephalograms and epilepsy occurred at significantly higher rates in children in the more impaired range of the autism spectrum (P<0.05). These findings suggest that the use of neurological investigative techniques such as electroencephalography should be a consequence of careful clinical evaluation and should be considered routinely during evaluation of more impaired individuals.