Liam O'Brien

Autism is a neurodevelopmental disorder characterized by impaired social interaction, impaired verbal and non-verbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child's life.[6]These signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress.[7] The diagnostic criteria require that symptoms become apparent in early childhood, typically before age three.[8]

Autism is caused by a combination of genetic and environmental factors.[2] Some cases are strongly associated with certain infections during pregnancy including rubella and use of alcohol or cocaine.[9] Controversies surround other proposed environmental causes;[10] for example the vaccine hypotheses, which have been disproven. Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood.[11] In the DSM V, autism is included within the autism spectrum (ASDs), as is Asperger syndrome, which lacks delays in cognitive development and language, and pervasive developmental disorder, not otherwise specified (commonly abbreviated as PDD-NOS), which can be diagnosed when the full set of criteria for autism or Asperger syndrome are not met.[8][12]