Thousands of people with autism have undiagnosed mental illness, study suggests

Thousands of autistic people have undiagnosed depression and anxiety, according to a new study from University College London reported in the i newspaper.

The study, published in The Lancet Regional Health – Europe, finds that at least one in every four cases of depression in autistic adults with learning disabilities is being missed. The researchers were not able to say how many undiagnosed cases this might represent, because there is not enough data either about the total number of autistic people in the UK or the incidence at which they experience particular conditions.

Previous research from the same team suggests that there are about 170,000 autistic adults with learning difficulties in the UK, out of a total autistic population of about 1.4 million.

“Autistic adults, particularly those with a learning disability, often find it hard to communicate with GPs about how they are feeling,” Dr Elizabeth O’Nions, a research fellow at University College London and lead author on the study, told i.

“Some people with a learning disability may also not recognise the need to tell someone about a health condition. This means that conditions where signs can’t be readily observed and a person must describe what has been happening to them may go undiagnosed.

“Different types of evidence and more thorough investigations may be needed to ensure that autistic people receive equal access to high-quality care.”

Because autistic people process information differently, they may benefit more from visual material than those who are not autistic, and less from “on the spot” verbal communication, the researchers say.

Autistic people more likely to have debilitating health conditions

The research team used data from GP practices throughout the UK to study 22,112 people – with and without learning disabilities – who received an autism diagnosis between 2000 and 2019.

They then compared these groups with people of the same age and sex, who had not been diagnosed as autistic.

Previous studies have indicated that debilitating health conditions are much more common among autistic people than they are among the general population.

The GP records of diagnoses did not reflect the full extent of the difference, however, suggesting that autistic people are much less likely to receive diagnoses for common health conditions.

The records showed that autistic adults were about twice as likely to have a GP record of self-harm and about 85% more likely to receive a new diagnosis of anxiety or depression compared to the general population.

Previous research, however, suggests that the true level of these conditions is even higher than that for autistic people. For example, one study found that older, highly-autistic adults were more than seven times as likely to have anxiety and five times as likely to report self-harm with suicidal intent.

The new research also showed that autistic adults with a learning disability were diagnosed with depressive disorders, harmful alcohol use, migraine, and neck or back pain much less frequently than the general population.

“This was particularly surprising, as previous research shows that these conditions are more likely to be common in autistic people with a learning disability than in the general population,” said Josh Stott, professor of ageing and clinical psychology at UCL.

Joshua Buckman, associate professor at UCL, said: “We suspect that most cases of these conditions are missed [in autistic adults with learning difficulties]. We think that both migraine and neck and back pain are more common in people with learning disabilities, because they have much higher rates of epilepsy, which is linked to migraine, and are more likely to be overweight, which is linked to back pain.”

He added: “We also know that many autistic people with learning disabilities suffer from mental health problems because they are often excluded from society.”