Attention deficit hyperactivity disorder (ADHD)

Attention-deficit hyperactivity disorder (ADHD) is a common psychiatric disorder first diagnosed in childhood and frequently persistent throughout adult life. The disorder is classically characterized by symptoms of inattention, impulsivity, and hyperactivity. Many children with ADHD go on to have problems related to education, social functioning, and/or other mental illness as adolescents and young adults. Although heritability estimates are consistently high, ADHD is a genetically complex disorder characterized by multifactorial inheritance involving numerous genes of moderate effect. Reports implicate variants of genes important for the synthesis, uptake, transport and receptor binding of dopamine in the etiology of ADHD. And interaction between the dopamine and serotonin systems has been implicated in both the pathophysiology of ADHD and the mechanism of action of widely used stimulant compounds.