autism

Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old.^[2] 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.^[3] It is one of three recognized disorders in the autism spectrum (ASDs), the other two being Asperger syndrome, which lacks delays in cognitive development and language, and Pervasive Developmental Disorder-Not Otherwise Specified (commonly abbreviated as PDD-NOS), which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.^[4]

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations, or by rare combinations of common genetic variants.^[5] In rare cases, autism is strongly associated with agents that cause birth defects.^[6] Controversiessurround other proposed environmental causes, such as heavy metals, pesticides or childhood vaccines;^[7] the vaccine hypotheses are biologically implausible and lack convincing scientific evidence.^[8] The prevalence of autism is about 1–2 per 1,000 people worldwide; however, the Centers for Disease Control and Prevention (CDC) reports approximately 9 per 1,000 children in the United States are diagnosed with ASD.^[9][10] The number of people diagnosed with autism has increased dramatically since the 1980s, partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.^[11]

Parents usually notice signs in the first two years of their child's life.^[12] The signs usually develop gradually, but some autistic children first develop more normally and then regress.^[13] Early behavioral or cognitive intervention can help autistic children gain self-care, social, and communication skills.^[12]Although there is no known cure,^[12] there have been reported cases of children who recovered.^[14] Not many children with autism live independently after reaching adulthood, though some become successful.^[15] An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.^[16]