AD/HD Under the Microscope

AD/HD sits at an uncomfortable crossroads of neuroscience, education, culture and commerce — simultaneously one of the most robustly replicated findings in child psychiatry and one of the most contested diagnoses in contemporary medicine. This article examines the construct's diagnostic evolution through DSM-5-TR and ICD-11, the under-recognised female phenotype, the striking findings from the Dunedin, E-Risk and Pelotas cohorts suggesting much apparent adult-onset AD/HD lacks childhood antecedents, and the competing evidence bases for and against validity — from heritability estimates of 74–80% and GWAS findings on one hand, to the relative age effect, trivially small neuroimaging effects, and pervasive diagnostic overlap with trauma, sleep disorders, anxiety, depression and personality pathology on the other. Drawing on the p-factor and HiTOP frameworks, Sonuga-Barke's pathway models and the MTA study's sobering long-term functional outcomes, the article argues that AD/HD is neither a simple neurobiological disease nor a social fiction but a genuinely impairing behavioural syndrome at its severe end whose diagnostic boundaries have drifted well beyond what the evidence supports — concluding with a "valid but overdiagnosed" position and practical recommendations for multi-informant, developmentally anchored, differential-diagnosis-rich assessment.