Original studyBMJ Mental Health, 2026Read the paper →
More adults are receiving an autism diagnosis than a decade ago, and the people behind those new records look different from those diagnosed in the past. Young adults and women now make up a much larger share of first diagnoses in both the UK and Sweden. A new analysis of national health records suggests that services are meeting a changing group of autistic adults, with different co-occurring health needs.
Researchers at the University of Bristol, Karolinska Institutet and partner institutions tracked adult autism diagnoses in UK primary care from 2010 to 2023 and in Swedish population registers from 2010 to 2021. The study appears in BMJ Mental Health. In the UK, more than 24.5 million adults contributed data, including 141,119 with an autism diagnosis and 38,858 first recorded diagnoses over nearly 156 million person-years. In Sweden, about 9.1 million adults contributed, including 100,817 with an autism diagnosis and 50,239 first recorded diagnoses.
Annual rates of first recorded autism diagnosis rose from 0.6 to 6.4 per 10,000 person-years in the UK between 2010 and 2023, and from 4.3 to 6.5 per 10,000 in Sweden between 2010 and 2021. The rise was steepest among 16–20 year-olds: from 3.1 to 36.4 per 10,000 in the UK, and from 16.5 to 36.1 per 10,000 in Sweden.
By the end of each study window, new diagnoses were higher in females than in males (UK 10.2 vs 6.7; Sweden 9.4 vs 8 per 10,000). Prevalence also climbed in the youngest adults. By the final year, 4.1% of 16–20 year-olds in both countries had an autism diagnosis on record. Age-standardised prevalence remained higher in males than females, but the male-to-female ratio fell from 4.1 to 2.2 in the UK and from 1.9 to 1.6 in Sweden.
Diagnoses rose faster among white and mixed ethnic groups in the UK and among adults with Swedish-born parents in Sweden than in other ancestral groups. Autistic advisers helped shape the research questions and interpret the findings.
The medical background of newly diagnosed adults shifted as well. In the UK, a prior record of epilepsy among those with a first autism diagnosis fell from 10% in 2010 to 4% in 2023, while a prior record of anxiety rose from 28.7% to 58.3%. Across both countries, prior intellectual disability and psychosis became less common, while ADHD, depression, sleep disorders, eating disorders and several other mental health conditions became more common.
Matching to non-autistic adults of the same age and sex showed that some rises in mental health history were larger among autistic adults than in the wider population. Similar directional changes appeared among all autistic adults, not only those newly diagnosed.
The study has clear limits. It is observational and relies on diagnoses as recorded in UK primary care or mainly Swedish secondary care registers, so misclassification and differences in data capture cannot be ruled out. Sweden’s data stop in 2021, while some UK patterns became clearer after that year. The analysis cannot say why the profile changed: better recognition of subtler or female presentations, wider diagnostic practice, or both, remain open questions.
Even so, the findings point to uneven access and rising diagnostic complexity. Planning for assessment and support may need to allow for more young adults and women seeking diagnosis, higher rates of co-occurring mental health conditions, and slower growth of diagnoses in some ethnic minority and immigrant groups.
