What people believe
The claim surfaces in newspaper columns, social media debates, and even some clinical conversations: ADHD is overdiagnosed, handed out too freely, an excuse for normal childhood behaviour or adult disorganisation. The implication is that the rising number of diagnoses reflects diagnostic inflation rather than genuine clinical need.
What the evidence says
The global picture is more complicated than either "overdiagnosed" or "underdiagnosed" captures. A 2024 systematic review and meta-analysis published in European Psychiatry, covering 117 studies and 103 independent data points, found a worldwide pooled prevalence of ADHD in children and adolescents of approximately 5–7%, and approximately 2.5% in adults.1 These figures have remained remarkably stable across decades of research — the actual prevalence rate has not changed. What has changed is the rate of diagnosis and treatment, which varies enormously by country, region, socioeconomic status, and demographic group.2
The 2025 review by Cortese and colleagues in World Psychiatry confirmed that adult ADHD prevalence sits around 2.5% worldwide, with up to 70% of individuals with childhood-onset ADHD continuing to experience impairing symptoms as adults.3 A separate analysis estimated that when symptomatic adult ADHD (regardless of childhood onset) is included, the figure rises to 6.76%, corresponding to approximately 366 million affected adults globally.4
The evidence suggests that ADHD is simultaneously overdiagnosed in some populations (young boys in well-resourced school systems with proactive screening) and dramatically underdiagnosed in others (women, adults, racial and ethnic minorities, people in countries with limited mental health infrastructure). A 2025 systematic review — the first post-COVID prevalence review — noted increases in ADHD diagnoses and prescriptions, particularly among adults, but attributed these primarily to improved awareness and diagnostic access rather than to a lowering of clinical standards.2
What to do instead
Replace the blanket claim with a more accurate statement: ADHD diagnosis rates are uneven. Some groups are diagnosed too readily, while others — particularly women, adults, and people in under-resourced settings — are missed for years or decades. The solution is not fewer diagnoses but better ones: comprehensive clinical assessment following established guidelines (NICE NG87, APA), rather than brief screening alone. If you are questioning whether your own diagnosis is valid, a thorough assessment by a clinician experienced in ADHD is the answer — not a media narrative about overdiagnosis.