Most autistic people over 40 are undiagnosed, research suggests

The majority of autistic people over the age of 40 in the UK are living without a diagnosis, a study suggests.

This could make them “more susceptible to age-related problems” and socially isolated in older age, researchers warned.

Autism is a neurodevelopmental condition and causes people to interact differently to others.

Those with the condition may get anxious in social situations, seem blunt, and struggle to understand what others are thinking or feeling.

For the study, published in the Annual Review of Developmental Psychology, experts at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London re-analysed research on UK healthcare record data from 2018.

They estimate that among middle-aged adults with autism – between 40 to 59 years old – some 91.45% of men and 79.48% of women are undiagnosed, with an overall underdiagnosis rate of 89.29%.

Among people aged from 60 to over 70 with autism, some 96.29% of men and 97.19% of women are thought to be undiagnosed, with a 96.51% underdiagnosis rate overall.

This compares with the estimated 52.54% of underdiagnosed 20 to 39-year-olds with autism and the 23.34% of underdiagnosed people under the age of 19.

Dr Gavin Stewart, British Academy postdoctoral research fellow at the IoPPN, said: “These very high underdiagnosis estimates suggest that many autistic adults will have never been recognised as being autistic, and will have not been offered the right support.

“This could make them more susceptible to age-related problems, for example being socially isolated and having poorer health.

“The high rates of underdiagnosis also mean that much of our research has systematically overlooked a large proportion of the autistic population, potentially skewing our understanding of how autistic people age, and leaving critical gaps in policy and services.”

Researchers also suggest autistic people in middle age are more likely to experience higher rates of conditions like Parkinson’s disease, arthritis and heart disease, as well as being more likely to self-harm.

They may also face greater barriers to healthcare, lower quality of life and more social isolation.

Francesca Happe, professor of cognitive neuroscience at the IoPPN, added: “Understanding the needs of autistic people as they age is a pressing global public health concern.

“As autistic people age, the nature of the challenges they face changes. We must adopt a lifespan approach that funds long-term research, integrates tailored healthcare, and expands social supports so that ageing autistic people can live happy and healthy lives.”

Published: 29/08/2025 by Radio NewsHub