Hypofrontality in attention deficit hyperactivity disorder during higher-order motor control: a study with functional MRI.

Functional magnetic resonance imaging (MRI) was used to investigate the hypothesis that attention deficit hyperactivity disorder (ADHD) is associated with a dysfunction of prefrontal brain regions during motor response inhibition and motor timing. Generic brain activation of seven adolescent boys with ADHD was compared to that of nine comparison subjects equivalent in sex, age, and IQ while they were performing a stop task, requiring inhibition of a planned motor response, and a motor timing task, requiring timing of a motor response to a sensory cue. The hyperactive adolescents showed lower power of response in the right mesial prefrontal cortex during both tasks and in the right inferior prefrontal cortex and left caudate during the stop task. ADHD is associated with subnormal activation of the prefrontal systems responsible for higher-order motor control. Functional MRI is a feasible technique for investigation of neural correlates of ADHD.