Reconceptualising ADHD as a neurobiological spectrum: calibration-based perspective

Although attention-deficit hyperactivity disorder (ADHD) diagnosis requires a categorical decision, phenotypic, twin and molecular genetic evidence indicates that ADHD traits are continuously distributed, with clinical ADHD at the functionally impairing end of this distribution. This paper proposes conceptualising ADHD as a neurobiological spectrum while treating categorical and dimensional approaches as complementary. A calibration perspective is proposed to describe graded differences in the regulation of attention, arousal, motivation and cognitive control, and their context-dependent expression. Genetic findings support dimensional continuity, whereas neurobiological and cognitive findings are consistent with graded regulatory variation. Functional impairment remains central to translating this dimensional framework into diagnosis and treatment decisions.