Autism and ADHD diagnoses have nearly tripled in Japan, and women in their 20s show a new ADHD peak
Sasayama D et al., 2026, JAMA Network Open (published Oct 20) https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2855501
Research letter; national claims cohort; about 1.62M new autism and 1.48M new ADHD diagnoses
Summary: Rising diagnosis rates are a common question, and national data covering almost a whole population is rare. The team used Japan’s national insurance claims database, which covers about 99% of residents, to track new diagnoses from 2010 to 2023. New diagnoses peaked at ages 5–9 for both conditions, and that peak rose about 2.7-fold for autism and 3.4-fold for ADHD. Since about 2013–14, new adult ADHD diagnoses have outpaced new adult autism diagnoses. In women aged 20–24, a second ADHD peak appeared around 2017 and is approaching the childhood peak; men show no similar pattern. About 46% of people with both diagnoses received them at the same visit. Limitations: claims data count people who were diagnosed and treated, not true community prevalence. Anxiety and mood codes weren’t available. The projected lifetime-risk figures assume rates stay stable, which they clearly haven’t.
Takeaways for clinicians:
It is further evidence that late-identified ADHD in young women is a large and growing referral group.
About 46% of people with both diagnoses got them at once. When diagnoses came one after another, autism usually came first, so a later ADHD diagnosis in an autistic patient fits a common pattern.
Diagnoses dropped in 2019–20 and rebounded in 2021, which may affect how wait-list and referral trends since the pandemic are read.
Takeaways for families:
More diagnoses don’t necessarily mean more autism or ADHD. These numbers count diagnoses in medical records, and better recognition and access probably play a big part.
Many women are first diagnosed with ADHD as adults.
About half of the people with both diagnoses got them at the same time.
