When thoroughly assessed, the prevalence of attention-deficit hyperactivity disorder (ADHD) in children/adolescents is estimated at 5%. There is no evidence that ADHD is over-diagnosed in the UK. Indeed, available data point to under-diagnosis, even though rigorous updated post-COVID-19 pandemic data are not available. Some cases may be misdiagnosed due to low-quality assessment, poor adherence to national guidance or inappropriate differential diagnosis. Beyond the controversy around over- or under-diagnosis and over-medicalisation of ordinary behaviours or emotions, the main issue is that UK clinical services cannot adequately support individuals with ADHD who need help. There is a risk that the narrative claiming 'ADHD is over-diagnosed' could be used to deny people with properly-diagnosed ADHD the care they deserve.
Cortese et al. (2026) studied this question.