Experts are warning that far from being over diagnosed, people with ADHD are waiting too long for assessment, support and treatment.
In a paper, published today in the British Journal of Psychiatry , a group of experts led by Professor Samuele Cortese from the University of Southampton say there is no robust evidence that ADHD is over-diagnosed in the UK.
The new paper refutes the view that 'nowadays everyone has ADHD' which is gaining traction in public discourse and has been amplified by some leading politicians, as demand rises for NHS assessments and services.
Bringing together academics, clinicians, people with lived experience and carers, the group say this narrative risks misleading the public and policymakers and overshadows a more pressing concern - unmet need.
Professor Cortese said: "Rather than focusing on increases or decreases in diagnostic rates, attention should be directed toward the extent to which those with ADHD are being adequately diagnosed and treated.
"While misdiagnosis and inappropriate diagnosis do occur, the available evidence indicates that under diagnosis and under treatment remain the predominant challenges."
When standardised diagnostic criteria are applied, the prevalence of ADHD internationally is around 5 per cent in children and 3 per cent in adults.
While prevalence has increased over time, NHS administrative data in England remains substantially below these expected levels, suggesting that many people with ADHD are living without a diagnosis and adequate support.
The group acknowledge that misdiagnosis can occur in some cases, particularly where assessments rely heavily on self-reporting or where alternative conditions are not fully considered.
Professor Tamsin Ford, Head of the Department of Psychiatry at the University of Cambridge, a coauthor on the paper, commented: "While many more people with ADHD are being recognised and treated, we are failing to support many more. Overdiagnosis is not a problem, but misdiagnosis may be as people are driven into the private sector by long waits; and sadly, missed diagnoses remain common."
The researchers stress that the absence of biological diagnostic markers means that thorough, multidisciplinary clinical assessment is essential. Field trials show that when clinicians are properly trained, an ADHD diagnosis is among the most reliable for a mental health condition.
"Similar to physiological traits, such as blood pressure or weight, ADHD symptoms are distributed along a continuum," says coauthor Professor Chris Hollis from the University of Nottingham. "But as with hypertension or obesity, there are diagnostic severity thresholds that determine health risks and what interventions should be used. Similarly, in ADHD a risk-stratified stepped-care approach may be useful."
Professor Cortese and colleagues highlight significant pressure on UK services, with long waiting times and growing demand, especially among adults who were not diagnosed in childhood.
They point to figures showing that around 27 per cent of children and young people diagnosed with ADHD reported waiting one to two years, while 14 per cent waited two to three years.
Evidence shows that untreated ADHD is associated with serious long-term risks, while effective treatments are available, backed by strong evidence, and generally well tolerated.
"The costs of untreated ADHD are often overlooked," says Professor Cortese. "They include increased risk of academic failure, suicidal behaviour, substance abuse, criminality, injury and death. The failure to provide treatments which have been shown to reduce these risks represents a major ethical issue that needs to be urgently addressed."
The authors call for improved funding, workforce training and a more balanced, evidence-based conversation to ensure accurate diagnosis while expanding access to care for those who need it.
The researchers are supported by the National Institute for Health and Care Research (NIHR), UK Research and Innovation (UKRI) and the Office for Life Sciences.
ADHD (over) diagnosis: fiction, fashion, and failure is published in the British Journal of Psychiatry and is available online .
