Blink rate in children with attention-deficit-hyperactivity disorder.

Spontaneous blink rate, a noninvasive measure of dopamine function, was coded in 28 children with attention-deficit-hyperactivity disorder (ADHD) and in 47 normal children during a listening, a conversation, and a verbal recall task. Unlike the normal children, the children with ADHD did not increase their blink rates significantly across these three tasks. The ADHD subjects were were not on stimulants had significantly lower blink rates than the normal children during verbal recall. The ADHD subjects on stimulants, however, had significantly higher blink rates than the normal subjects during the listening task. These preliminary findings are discussed in light of their potential implications for theories on neurotransmitter dysfunction and arousal in ADHD.