Attention deficit hyperactivity disorder (ADHD) is a heterogeneous disorder of unknown aetiology. It usually affects school-aged children with an estimated prevalence of 3 to 6%. ADHD is characterised by a core of symptoms that include short attention span, easy distractibility and social impulsivity.
Stimulants continue to be the most efficacious and least toxic agents used to treat the disorder in the majority of children, and are the drugs of choice in children in whom cardiovascular status is questioned. Tricyclic antidepressants are also effective and are especially beneficial in individuals who are resistant to stimulants or in whom ADHD is accompanied by comorbid depression, anxiety, enuresis, tic disorders, substance abuse or sleep disturbance. Other antidepressants such as clorgiline (clorgyline), nortriptyline, fluoxetine and monoamine oxidase inhibitors have also been shown to reduce ADHD symptomatology. These agents may provide therapeutic options in the future.
Adverse effects associated with stimulants include decreased appetite, insomnia, gastrointestinal upset, headache and potential growth suppression. Tricyclic antidepressants may cause drowsiness, anticholinergic effects and cardiovascular changes. Tolerance does not development with stimulants but may occur with tricyclic antidepressants.