Some Facts about Autism
05 January 2013
Author : Courtesy: Internet

Some facts about Autism

The epidemiology of autism is the study of factors affecting Autism Spectrum Disorders (ASD).A 2012 review of global prevalence estimates of autism spectrum disorders found a median of 62 cases per 10,000 people. ASD averages a 4.3:1 male-to-female ratio. The number of children known to have autism has increased dramatically since the 1980s, at least partly due to changes in diagnostic practice; it is unclear whether prevalence has actually increased and as-yet-unidentified environmental risk factors cannot be ruled out. The risk of autism is associated with several prenatal factors,including advanced parental age and diabetes in the mother during pregnancy. ASD is associated with several genetic disorders and with epilepsy, and autism is associated with mental retardation.

Autism and itscauses

Autism is acomplex neurodevelopmental disorder.Many causes have been proposed, but its theory of causation is stillincomplete. Autism is largely inherited, although the genetics of autism are complex and it is generally unclear which genes are responsible. Little evidence exists to support associations with specific environmental exposures.

In rare cases,autism is strongly associated with agents that cause birth defects. Other proposed causes, such as childhood vaccines, are controversial and the vaccine hypotheses lack convincing scientific evidence


Although incidence rates measure autism risk directly, most epidemiological studies report other frequency measures, typically point or period prevalence, or sometimes cumulative incidence. Attention is focused mostly on whether prevalence is increasing with time

Incidence and prevalence

Epidemiology defines several measures of the frequency of occurrence of a disease or condition

In autism epidemiology, point or period prevalence is more useful than incidence, as the disorder starts long before it is diagnosed, and the gap between initiation and diagnosis is influenced by many factors unrelated to risk. 

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