Hundreds of thousands of adults may be living with undiagnosed attention deficit hyperactivity disorder (ADHD), according to a new review by UK researchers. The study highlights a significant gap between recorded diagnoses and estimated prevalence, particularly among older adults.
While awareness and diagnosis rates for ADHD have increased in recent years, especially after 2020, the number of recorded cases remains substantially lower than international estimates suggest. For adults over 65, the diagnosis rate is as low as 0.05%, indicating that over 90% of cases in this age group may go unrecognized. Researchers from King's College London, University College London, and the University of Liverpool emphasize that these low rates do not necessarily reflect a lower incidence of ADHD in older populations, but rather historical difficulties in recognition and access to diagnosis.
Historically, ADHD was less understood, and individuals, particularly women, often navigated life without the support a diagnosis can provide. The review utilized anonymized data from over 3.5 million individuals registered with GP practices in England in 2025 and compared it with international prevalence estimates from over 42 million patients. This analysis examined trends over a 24-year period.
The findings indicate that ADHD is likely underdiagnosed across all age groups. Dr. Gavin Stewart, the study's lead author, noted that a timely diagnosis often serves as a critical gateway to essential support, which is crucial as individuals age. He added that the majority of aging neurodivergent individuals remain undiagnosed and unsupported, a situation that urgently needs to be addressed.
ADHD can significantly impact various life aspects, including education, work, and relationships, and it frequently co-occurs with other neurodevelopmental conditions. A previous study indicated that adults with ADHD have reduced life expectancies. When undiagnosed or unsupported, individuals may struggle for years to understand the challenges they face. Experts suggest that the rise in ADHD diagnoses and medication use reflects a growing recognition of ADHD as a lifelong condition, necessitating healthcare systems to plan for increasing demand.
Official data from NHS England suggests that as many as 2,498,000 people in the UK could be living with ADHD, including those not yet formally diagnosed. Concurrently, the number of patients waiting for autism assessments has also seen a notable increase. Experts warn that these figures represent a growing number of middle-aged and older adults struggling to access vital support services. The proportion of people in the UK on ADHD medication has tripled in the past decade, with a particularly sharp increase among young women.