Autism diagnoses are rising fastest among adults in their late 20s and 30s

New research shows autism diagnoses are climbing most sharply among U.S. adults ages 26 to 34, with women driving much of the increase. A Denver-area psychologist says the pattern reflects better recognition of autistic women, not a sudden rise in autism itself.

Why it matters: - Autism is being identified later in life at a much higher rate, especially among women who were missed as children. - The shift affects how adults understand long-standing anxiety, depression, ADHD and relationship struggles. - The trend is changing demand for adult autism evaluations, counseling and support services.

What happened: - Research drawn from more than 12 million members of integrated health systems found the largest relative increase in autism diagnosis from 2011 to 2022 was among adults ages 26 to 34, up 450%. - Separate analysis of 2024 patient records found one in four female patients diagnosed with autism received that diagnosis at age 19 or older. - The same analysis found the adult-diagnosis rate among men was 12%. - Dr. Steffanie Stecker, a licensed psychologist and founder of Mountain Vista Psychology in Englewood, Colo., said her practice is seeing the same pattern. - Mountain Vista Psychology offers psychological testing, counseling and neurofeedback for children, teens and adults across the south Denver metro area. - The practice has offices in Englewood, Greenwood Village, Littleton and Hampden South Denver.

The details: - Stecker said many autistic women were missed because autism research and diagnosis were historically based on how it presents in boys. - She said many women learn to mask by rehearsing conversations, forcing eye contact, copying expressions and suppressing self-regulating movements. - Stecker said masking can allow a person to build a career, marriage and family while quietly becoming exhausted. - Many adult patients arrive with earlier diagnoses including anxiety, depression, ADHD or a personality disorder. - Stecker said those diagnoses can describe the effects of masking without explaining why the symptoms are happening. - Research published in the past month concluded that the recent rise in U.S. autism diagnoses is being driven mostly by recognition of women and girls, not by a true increase in how common autism is. - Stecker said the key shift is better detection, not a new wave of autism. - Mountain Vista Psychology's adult evaluation process spans several appointments and includes a testing session of about four hours plus a feedback meeting. - Stecker said not every adult who seeks an assessment receives an autism diagnosis, but the evaluation often still provides clarity.

Between the lines: - The rise in adult diagnoses suggests many people reached adulthood with autism undetected, then sought answers after years of managing symptoms on their own. - The debate over social media and self-identification is growing, but Stecker framed the issue as one for clinical assessment rather than argument. - The pattern also points to a broader correction in mental health practice: clinicians are recognizing presentations that do not fit older male-centered diagnostic models. - For practices that evaluate adults, more awareness may translate into more referrals from people who have long suspected autism but never had language for it.

What's next: - More adults are likely to seek formal autism assessments as awareness of late diagnosis grows. - Clinicians will likely face continued debate over self-recognition, self-diagnosis and the role of social media in prompting evaluations. - Practices that serve adults may see stronger demand for multi-visit testing and follow-up counseling. - Further research is likely to keep examining whether the diagnosis surge reflects improved recognition, changing referral patterns or both.

The bottom line: - The fastest growth in autism diagnosis is happening in adults, not children, and women are driving much of it.