ADHD Diagnosis Debate Collapses Without Baseline Rate

A Channel 4 documentary about ADHD diagnosis has prompted a complaint from the ADHD Foundation, with some outlets calling it the year's most controversial show.

The real controversy isn't whether the filmmakers got the science right. It's that both sides are arguing from a premise nobody in the field has actually established.

The documentary's thesis is straightforward. ADHD is overdiagnosed. The charity's complaint is equally straightforward. This harms people who need help. But beneath both positions sits an identical, unexamined assumption—both assume that a "true" prevalence rate of ADHD exists somewhere in the population and that you can measure how far actual diagnosis numbers exceed it.

The DSM-5 criteria for ADHD are symptom thresholds, not biomarkers. You cannot draw blood and find ADHD, and you cannot scan a brain and point to it. The condition is defined entirely by behavioral checklists and functional impairment observed by clinicians—which means there is no established biological prevalence rate to compare against. The charity and the documentary are arguing about a ratio with no denominator.

This is not a conflict between evidence and activism, it's a conflict between two incompatible frameworks pretending the ground beneath them is settled.

In neurodevelopmental medicine, this gap between diagnosis and biomarker is why the field still debates whether ADHD is a discrete disorder or a spectrum where the boundary between "real" and "overstated" collapses entirely. Some researchers argue that ADHD represents the tail of a normal distribution of attention regulation, not a disease category. If that's true, then "overdiagnosis" is a category error—like complaining we're overdiagnosing introversion. This is not a conflict between evidence and activism, it's a conflict between two incompatible frameworks pretending the ground beneath them is settled.

The complaint and the documentary will continue circling each other because neither has to answer the question that would actually matter. What makes a diagnosis correct? When you evaluate claims about systems you depend on—healthcare, education, hiring practices—you inherit the same unstated assumption both sides here accept without proof. You assume the boundary between legitimate need and false positive is real and knowable. Usually it isn't. Usually you're just choosing which error you're willing to tolerate and calling the other side's framework a scandal.