The prevalence of autism in the CDDS dataset, the longest of the three data records, increased from 0.001% in the cohort born in 1931 to 1.2% among 5 year-olds born in 2012. This increase began around ~ 1940 at a rate that has gradually accelerated over time, including notable change points around birth years 1980, 1990 and, most recently, 2007.
This review summarizes results that correlate the timing of changes in incidence with environmental changes. Autism could result
from more than one cause, with different manifestations in different individuals that share common symptoms.