Role of Executive Function in ADHD

Attention-deficit/hyperactivity disorder (ADHD) is a neuropsychiatric disorder characterized byinattention, hyperactivity, and impulsivity. ADHD is commonly treated with behavioral therapy andnoradrenergic and dopaminergic pharmacotherapy with psychostimulants such as methylphenidateand dextroamphetamine. Stimulants primarily have dopaminergic and noradrenergic mechanisms ofaction, with blockade at the dopamine transporter reducing reuptake, resulting in an increase in theseneurotransmitters at the synapse. Theoretically, inattention, hyperactivity, and impulsivity in ADHDmay be due to underlying executive functioning, alerting, and orienting deficits, and the nonstimulantmodafinil could be beneficial in managing symptoms of ADHD by improving these components ofattention that accompany wakefulness. Although modafinil exhibits a small degree of dopaminergicaction by blocking the dopamine transporter, the major effect of modafinil may be attributable to neuronalactivity in the hypothalamus, particularly pertaining to the recently discovered peptideshypocretin 1 and 2 (also known as orexin A and B). However, further placebo-controlled and flexibledosestudies are needed to determine the efficacy of modafinil in treating the symptoms of ADHD inchildren and adults.