Attention-deficit/hyperactivity disorder (ADHD) is increasingly diagnosed across the lifespan, yet there is a growing tendency to treat diagnoses as permanently fixed once assigned. Diagnosis requires not only the presence of characteristic symptoms but also clinically significant functional impairment that is most appropriately explained by ADHD, rather than another condition. Longitudinal evidence demonstrates that ADHD trajectories are heterogeneous and non-linear, with fluctuating symptom…
