Global prevalence of autism: A systematic review update.
Jinan Zeidan, Eric Fombonne, Julie Scorah and 6 others
PMID 35238171WHAT IT FOUND
The median global autism prevalence is 100 per 10,000, but estimates vary wildly from 1.09 to 436 per 10,000.
This huge spread is driven by how cases are found and defined, not just by biology or geography.
Key findings
01The median prevalence of autism was 100 per 10,000, with a range from 1.09 to 436 per 10,000 across studies.
02Prevalence estimates are highly variable, largely due to differences in how cases are identified and defined rather than true population differences.
03Studies using active case-finding methods generally yield higher prevalence estimates than those relying on administrative records.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The review protocols were not pre-registered. No formal appraisal of the methodological quality of the included studies was conducted. Variability in diagnostic criteria (DSM vs ICD) and case-finding methods across studies makes direct comparison difficult. Many regions, particularly Africa and the Middle East, still have limited data.
Declared interests
The authors declared no known conflicts of interest. The work was funded by the Canadian Institutes of Health Research and Fonds de Recherche du Québec - Santé.
The easy way to misread this
Do not interpret the wide range in prevalence estimates as evidence of true biological differences between regions. The variation is largely explained by methodological differences in how cases are found and defined, meaning lower estimates in some areas may reflect under-diagnosis rather than lower actual prevalence.