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 say there is no robust evidence that ADHD is over-diagnosed in the UK. They refute the view that ‘nowadays everyone has ADHD’, which is gaining traction in public discourse, 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 Tamsin Ford Mental Health Research Lead for the Cambridge Children’s Hospital project and Head of the Department of Psychiatry at the University of Cambridge, was a senior co author on the paper.
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. Sadly, missed diagnoses remain common.
Professor Tamsin Ford, Mental Health Research Lead, Cambridge Children’s Hospital
Cambridge Children's Hospital
The editorial highlights that a group of children where ADHD may tend to be missed or under diagnosed are those that have co-occurring conditions. One such group is children with long term physical health problems, who have elevated rates of ADHD. This is often under-detected and under-treated.
Cambridge Children's Hospital aims to fully integrate physical and mental healthcare, including detecting and treating neurodevelopmental conditions such as ADHD in children who also have physical health needs.
Early detection and intervention have a positive impact on emotions, behaviour, educational attainment and peer relationships, as well as helping children cope with the health care they may need to receive, such as staying in hospital, procedures or operations.
Studies have shown that children with epilepsy have up to twice six times the population rate of ADHD, yet often have difficulty obtaining treatment but when they are successfully treated there is a significant improvement in functioning and quality of life.
Improving diagnosis
Professor Samuele Cortese from the University of Southampton, the study’s first author, 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.
Professor Samuele Cortese, University of Southampton
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.
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 amongst the most reliable for a mental health condition.
Professor Chris Hollis from the University of Nottingham, a co-author, said: “Similar to physiological traits, such as blood pressure or weight, ADHD symptoms are distributed along a continuum. 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.”
The team 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 around 27 per cent 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,” said 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.
Professor Samuele Cortese, University of Southampton
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.
Reference
Cortese, S et al. ADHD (over) diagnosis: fiction, fashion, and failure. British Journal of Psychiatry; 5 March 2026 (opens in a new tab)
Adapted from a press release from the University of Southampton