The number of people with autism in England may be twice as high as previously thought, analysis from University College London (UCL) suggests.
Data collected from GP records show that almost 750,000 adults have undiagnosed autism in England.
The researchers estimate that the total autistic population in England is over 1.2 million, nearly double the figure of 700,000 cited by the government for the entirety of the UK.
The findings, published in The Lancet Regional Health Europe, suggest that many autistic adult’s needs are not being met and the researchers are calling for better access to diagnostic services for adults.
Autism occurs from birth and affects how a person’s brain works, meaning they see and experience the world differently from other people. It has long been seen as a paediatric condition meaning many adults missed out on a diagnosis when they were younger when less was known about autism. A diagnosis can enable people with autism to access the help they need to access health care and support everyday living.
The researchers used anonymised data from the IQVIA Medical Research Data (IMRD) database to look at more than five million individuals registered at GP practices in England who had received an autism diagnosis between 2000 and 2018.
The figures were compared with a lower and higher estimate of autism levels in the UK population. The low estimate is that one per cent of the population has autism and is based on research conducted in 2011 before diagnostic criteria became more inclusive. The upper estimate suggests that three per cent of the population has autism and is based on rates of diagnosed autism in young people aged 10-19 in the researcher’s data set.
Rates of diagnosed autism in children and young people were much higher than in adults and older adults. The findings suggest that between 150,000 and 500,000 people between the age of 20 and 49 may be autistic and undiagnosed, and between 250,000 and 600,000 autistic people over the age of 50 may be undiagnosed.
Lead researcher Elizabeth O’Nions from UCL said: ‘Our findings indicate that there is still a substantial diagnostic gap in adults compared to children and young people when it comes to autism in England.’
She explained that this matters because autistic people often experience discrimination and exploitation in society and often have unmet support needs, even when they appear to be coping with life.
The differences in diagnosis levels may arise from a lack of awareness and understanding of autism in adults on the part of healthcare professionals, as well as older adults being less likely to both self-identify as autistic and seek medical advice.
The researchers state that the substantial age-related differences in diagnosis suggest an urgent need to improve access to adult autism diagnostic services and support post-diagnosis.
Ms O’Nions said: ‘Providers may be hesitant to raise the issue of autism given the uncertainty around waiting times for a diagnosis and the availability of support or specialist services post-diagnosis.’
She added: ‘Having a diagnosis means that someone can advocate for their right to reasonable adjustments and the support they need.’