Autism Goes Undiagnosed In About 90% Of Over-40s. I Asked Experts How To Spot It

You might have heard that autism diagnoses are on the rise in the UK. Some even argue it’s being “overdiagnosed”. 

But the National Autistic Society says that about 750,000 autistic adults in the UK remain undiagnosed. And a 2025 review estimated that 89% of autistic adults over 40 remain undiagnosed, with that figure rising to 96% for over-60s.

Here, HuffPost UK spoke to the review’s author, research fellow and co-leader of the ReSpect Lab, Dr Gavin Stewart, about why those numbers might be so how...