Diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) has soared in recent years, but researchers have found it’s still under-recognised and under-diagnosed, especially in adults over the age of 65.
About 2.5million people in the UK have ADHD, according to the NHS. Data published in March 2026, also revealed a further 683,088 had been referred for an ADHD assessment – an increase of more than 130,000 on the previous year.
A study led by researchers at UCL, University of Liverpool and King’s College London revealed rates of new ADHD diagnoses increased after 2020 across most age groups.
The highest rates were observed in boys under 18-years-old, while increases among adults were particularly notable in women. But diagnosis rates among adults aged 65 and over remained consistently low.
Lead author Dr Amber John, who began the research at UCL before moving to the University of Liverpool, said: “The low rates observed in older adults don’t necessarily mean that ADHD is uncommon in older age.
“Instead, they may reflect historical differences in recognition and access to diagnosis, particularly among generations who grew up before ADHD was widely recognised.”
In the study, published in the journal The Lancet Regional Health Europe, researchers found that while 1.19% of people in England had an ADHD diagnosis in their primary care record, recorded diagnosis rates were notably lower across all age groups compared with the international estimates of actual ADHD prevalence, which typically range between 3% and 5%.
This gap was especially large in older adults, with just 0.05% of men and women over the age of 65 diagnosed with ADHD.
The researchers say their findings show that while diagnosis rates for ADHD have increased substantially over the past decade for children and adults, recorded diagnoses of ADHD in England are still lower than the best available estimates of ADHD prevalence.
Data from more than 3.5 million people registered with GP practices in England in 2025 was used to estimate the proportion of people with a recorded ADHD diagnosis at this time.
Researchers then compared this with published estimates of ADHD prevalence in the general population from international studies and used data from more than 42 million patients in England to examine diagnostic trends in ADHD from 2000 to 2024.
“When we compared recorded ADHD diagnoses with published estimates of how common ADHD is in the population, we found a substantial gap across every age group,” Joint first author Dr Gavin Stewart, British Academy Research Fellow at the Institute of Psychiatry, Psychology & Neuroscience, King’s College London, said.
“This gap was especially large in older adults, suggesting that many people may have gone unrecognised,” he added.
Dr Angela Hind, Chief Executive of the Medical Research Foundation, commented: “ADHD can profoundly affect many aspects of a person’s life – education, work, relationships – and it often co-exists with other neurodevelopmental conditions.
“When it goes undiagnosed or unsupported, people may spend years not understanding the challenges they face.
“We’re proud to support research that will help strengthen ADHD services and ensure more children and adults can get the recognition and help they need.”
