ADHD Across the Lifespan: Reconsidering Assumptions of Diagnostic Permanence

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 expression and variable relationships to functional impairment. Rather than conceptualising an ADHD diagnosis as permanently fixed, greater recognition of this complexity supports longitudinal clinical formulation and more adaptive biopsychosocial care across the lifespan.