Diagnosis Demographics

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Key Findings
The median age at autism diagnosis declined slightly from 7 years of age in 2015 to 6 years in 2024. Male patients are increasingly diagnosed earlier with the median age at diagnosis dropping from 7 years in 2015 to 5 in 2024. However, the median age for females remained near 8 years over the same period.

Of male patients diagnosed with autism in 2024, 44% were under age 5. In that same year, 34% of diagnosed females were under age 5, indicating more than half of patients were diagnosed later than age 5 and might have benefitted from earlier diagnosis.

The proportion of female patients diagnosed as adults (ages 19+) was 25% in 2024, while 12% of males were diagnosed with autism as adults in the same year.

To understand trends in ASD diagnoses over time, we studied 338,415 patients with a pattern of established care who received their first ASD diagnosis between 2015 and 2024. We found that the overall average age at ASD diagnosis remained stable at around 10.5 years, while the median age decreased from 7 in 2015 to 6 in 2024. When the average is higher than the median, it typically reflects a small but significant group being diagnosed much later, potentially into adulthood, which pulls the average upward.

Among male patients, diagnoses are increasingly occurring earlier, with the median age at diagnosis dropping from 7 to 5 and the average age dropping from 10.2 to 9.2 over the study period. In contrast, the median age for female patients has stayed consistent at about 8 years, while the average age at diagnosis increased from 11.7 years in 2015 to 13.1 years in 2024.

We then examined the age distribution at the time of autism diagnosis. Early detection has become more common among male patients, with 44% diagnosed before age 5 in 2024, compared to 34% of females. In contrast, nearly one in four female patients with ASD were diagnosed as adults (age 19 or older), more than double adult diagnoses among males (12%). More than half of both males and females were diagnosed after age 5 and might have benefitted from earlier diagnosis.