Diagnosis.

Diagnostic Thresholds, Prevalence, and Overdiagnosis

ADHD prevalence is stable at 5.3–7.6% when standardized procedures are used, but diagnostic thresholds—symptom count, impairment requirement, informant rules—determine who gets counted. The youngest children in a classroom are diagnosed 60% more often than the oldest, not because of neurological differences, but because teachers compare them to older peers. The evidence refutes both 'diagnoses are exploding' and 'diagnoses are fake.'