Dear Sir, We read with great interest Sibley et al.'s article (1) examining ADHD symptoms longitudinally in a cohort without a baseline childhood diagnosis.

The authors identified cases of possible late-onset ADHD via screening and then used an iterative process to rule out non-true cases. The overwhelming majority did not have true late-onset Adult ADHD, but had childhood ADHD symptoms, or did not have the disorder (rather, cognitive impairment due to heavy substance use or other psychiatric morbidities).