Autism rates began to increase notably in the early 1990s, with a steady rise continuing through the 2000s and 2010s. Significant increases in autism diagnosis rates were documented from birth cohorts in the late 1980s and throughout the 1990s, continuing into the 2000s. For example, autism incidence in California rose 7- to 8-fold from the early 1990s through the 2000s, with diagnoses becoming more common in younger children during this period. The broadening of diagnostic criteria, increased awareness, earlier age at diagnosis, and inclusion of milder cases all contributed to this rise. However, these factors alone did not fully explain the magnitude of increase, and some experts consider a possible true increase in autism cases. More recently, rates have continued to rise, with a 175% increase in diagnoses over a decade from 2011 to 2022 documented in a large study examining health records, and the prevalence now reported as about 1 in 31 children in the U.S. by 2022.
Key Points on When Autism Rates Increased
- Early 1990s: steady rise begins observed in population data.
- 1990-2000s: rapid increase in incidence confirmed in California and other regions.
- 2011-2022: 175% increase in autism diagnoses noted in large U.S. population studies.
- Diagnostic changes and awareness boosts began especially after the 1990s.
- Continued rise through 2020s with current prevalence about 1 in 31 in children.
This timeline shows that the notable increase started in the 1990s and has persisted, influenced by multiple factors including diagnostic practices and possibly some true increase in prevalence.
