By Julia Belluz
If you were to believe newspaper reports and anecdotal evidence about autism, you probably think rates of the disorder are exploding around the world.
But a new study — the most extensive review of the data on the global prevalence and incidence of autism, published in the journal Psychological Medicine — actually found rates have remained unchanged since 1990.
“This study drew together research findings on autism spectrum disorders conducted across the world over the past 20 years,” says study lead Amanda Baxter.
7.5 per 1,000 had autism in 1990; 7.6 per 1,000 had it in 2010
Studies using different methods and sample sizes reported a range of prevalence estimates, though few actually reported an increase. When Baxter and her co-authors adjusted for differences in the study methods and synthesized the results, they found no evidence for a growth in the prevalence of autism spectrum disorders over time and little regional variation.