Objective measurement of hyperactivity and attentional problems in ADHD

Objective: To precisely describe movement abnormalities in seated children with attention-deficit hyperactivity disorder (ADHD) while they were engaged in a continuous performance task (CPT). Method: Diagnoses were made by using structured interviews (Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic Version) and DSM-IV criteria. Movement patterns of 18 boys with ADHD (9.3 +/- 2.4 years) and 11 normal controls (8.6 +/- 1.8 years) were recorded using an infrared motion analysis system that tracked the position of four markers 50 times per second to a resolution of 0.04 mm. Results: Boys with ADHD moved their head 2.3 times more often than normal children (p < .002), moved 3.4 times as far (p < .01), covered a 3.8-fold greater area (p < .001), and had a more linear and less complex movement pattern (p < .00004). They responded more slowly and with greater variability on the CPT. Complexity of head movement and variability in response latency significantly correlated with teacher ratings. A predefined composite of movement and attention discriminated 16 of 18 patients from 11 of 11 controls. Conclusions: The relative inability of boys with ADHD to sit still can be objectively verified, and ''fidgeting'' appears to consist of more frequent, larger amplitude, whole body movements.