The relationship between motor performance, attention deficit, impulsiveness, and hyperactivity in 42 school-aged children with ADHD (36 males, 6 females; mean age 8 years 2 months; range 6-11 years) was studied at National Taiwan University, Taipei, Taiwan. Children with ADHD had significantly impaired performance in fine and gross motor skills, as measured by the Bruininks-Oseretsky Test of Motor Proficiency and compared to 42 age-and sex-matched children without ADHD. Attention, impulse control, and parent ratings of activity level were the best predictors of gross motor skills, while attention and impulse control were the best predictors of fine motor skills for children with ADHD. Different behavioral processes may be involved in fine and gross motor performances. 
COMMENT. Children with ADHD-combined type perform poorly in tasks that measure motor performance, attention, impulse control, and activity level. Sustained attention and impulse control are important predictors of both fine and gross motor skills. In this study, hyperactivity is a predictor of gross motor incoordination but is not significantly correlated with fine motor skills. Measures of motor performance should be included in the diagnostic criteria for ADHD. Based on the frequency of subtle neurologic abnormalities in children with ADHD and impaired motor performance (eg. tandem gait dyspraxia, impaired alternating forearm movements, mirror movements), a primary motor deficit is a more likely explanation than motor incoordination secondary to impaired attention and lack of impulse (inhibitory) control. Subclinical epileptiform abnormalities in the EEG are more prevalent in children with ADHD, especially the hyperactive/impulsive subtype (Deonna et al, 2000; Becker et al, 2004).