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Causes of Autistic Spectrum Disorders

The causes of Autism Spectrum Disorders have not been fully understood, but it seems clear that these conditions reflect abnormalities of the functioning of certain brain centers, and that these are abnormalities that arise before birth. Various different brain centers have been implicated, and one hypothesis is that there is a general problem in how the brain grows and develops that underlies this condition [ref].

Genetic factors account for a large part of the risk of developing this spectrum of disorders, though which genes in particular are responsible for this condition is still not clear [ref, ref]. When one child in the family has an Autism Spectrum Disorder, there is about a 5% chance that each next child could have a similar condition, and this risk becomes higher when there are two siblings with the condition [ref].

Environmental factors are also assumed to be implicated in the development of Autism Spectrum Disorders, likely by impacting on a person's genetic vulnerabilities. Multiple different environmental causes have been considered, including infectious disease, heavy metals, solvents, environmental pollutants, industrial chemicals, pesticides, alcohol, smoking, illicit drugs, vaccines, and prenatal stress [ref]. So far, there is little evidence supporting these different theories. The idea that vaccines could cause Autism has been debunked.


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Course & Prevalence