Nearly 90% of adults with autism remain undiagnosed

Nearly 90% of autistic adults aged 40–59 are undiagnosed in the UK, rising to over 96% among those over 60, according to new research.

A recent study highlights a ‘lost generation’ of autistic adults as diagnosis rates sharply decline with age.

Experts from Foxholes Care Home analysed a study by King's College London of autistic individuals across the country, revealing vast differences between the age groups. 

Improving awareness and access to assessment in later life is essential not just for diagnosis, but to ensure older adults receive care that is compassionate, personalised, and truly meets their needs

While awareness and diagnosis of autism have improved among children and young people, the data reveals a widening diagnostic gap among older age groups, particularly those aged over 40, many of whom grew up before autism was widely recognised or understood.

Almost 90% of autistic adults aged 40 and over in the UK remain undiagnosed overall. Of those 91.45% are male and 79.48%are female, showing a gender divide in obtaining a diagnosis.

Among older adults the number of undiagnosed skyrockets,with 96.29% of men and 97.19% of women undiagnosed.

Neil Gandecha from Foxholes Care Home said: “For many older adults, an autism diagnosis was never even an option when they were growing up. 

“Recognising autism later in life can still make a meaningful difference, improving understanding, care, and quality of life.

“For those who suspect they or a loved one may be autistic,there are clear steps that can be taken to seek support and assessment.”

How to seek an autism assessment as an adult in the UK

• Start with your GP
  You can request a referral for an adult autism assessment. Book an appointment and explain why you believe you may be autistic, including lifelong traits such as sensory sensitivity, social difficulties, or burnout. Write it all down before the appointment so that you are ready

• Ask for an NHS referral and know your rights
  Adults in England can request a referral under the Right to Choose scheme, which may offer faster assessment through approved private providers

• Prepare evidence of lifelong traits
  Clinicians look for signs present since childhood. Old school reports, family observations, or written examples of long-term patterns can support a referral

• Expect long waiting times
  NHS waiting lists can range from months to several years. Some adults choose private assessments, which typically cost £1,000-£2,500

• A diagnosis isn’t required for support
  Workplace adjustments and mental health support can often be requested without a formal diagnosis.

• Support is available at any stage
  Autism charities, peer groups, and online resources can help while waiting for assessment or for those who choose not to pursue a diagnosis

Gandecha said: “As a care home manager, these findings are deeply concerning, but not surprising.

“Many older adults in care settings have lived their entire lives without understanding why they struggled with communication, change, or sensory environments.

“Without recognition of autism, behaviours are too often misunderstood rather than supported.

“Improving awareness and access to assessment in later life is essential not just for diagnosis, but to ensure older adults receive care that is compassionate, personalised, and truly meets their needs.”