Autism diagnosis rates rise due to expanded criteria and awareness

The rising number of autism spectrum disorder diagnoses globally is attributed to several factors, including broader diagnostic criteria, increased social awareness, and improved screening processes. While the steep upward curve in diagnoses can appear to be an epidemic, researchers distinguish between the number of diagnosed cases and the actual biological incidence of the condition.

In the United States, estimates have shifted from approximately 1 in 150 children in 2000 to 1 in 31 in recent years. In Italy, the Istituto Superiore di Sanità estimates a prevalence of about 1 in 77. Data from surveillance systems, such as the CDC’s ADDM Network, show a gradual increase of 10-20% every two years in many high-income countries, a trend consistent with changes in medical practice rather than a sudden biological explosion.

Scientific debate continues regarding whether environmental or biological factors, such as the gut-brain axis or microbiota, play a role in the increase of more severe cases. However, studies suggest that a significant portion of the rise, particularly in cases without severe intellectual disabilities, is due to how the condition is identified and recorded.