What are the effects of treatments?

LIKELY TO BE BENEFICIAL

Dexamfetamine

Limited evidence from two systematic reviews suggests that dexamfetamine versus placebo significantly improves some behavior outcomes but increases anorexia and appetite disturbance. The second systematic review could not draw firm conclusions about the effects of dexamfetamine versus methylphenidate.

Methylphenidate

A systematic review has found that methylphenidate versus placebo significantly reduces core symptoms in children five to 18 years of age, but may disturb sleep and appetite. The review could not draw firm conclusions about the effects of methylphenidate versus dexamfetamine or versus tricyclic antidepressants. The review also found that methylphenidate versus psychologic/behavior treatment improves symptoms in the medium term, but the clinical importance of these findings is unclear.

Methylphenidate plus behavior treatment

One systematic review found inconsistent results for combination treatments (medication plus psychologic/behavior treatment) versus placebo. A second systematic review has found that combination treatments versus psychologic/behavior treatments alone significantly improve symptoms of attention-deficit/hyperactivity disorder (ADHD).

UNKNOWN EFFECTIVENESS

Clonidine

Limited evidence from one systematic review suggests that clonidine versus placebo for four to 12 weeks reduces core symptoms, but the clinical importance of these findings is unclear.

Psychologic/behavior treatment

One systematic review of two small randomized controlled trials (RCTs) found insufficient evidence about the effects of psychologic/behavior treatment versus standard care. One large subsequent RCT found no significant difference between psychologic/behavior treatment versus standard care in behavior rating scales.

Definition

ADHD is “a persistent pattern of inattention and/or hyperactivity and impulsivity that is more frequent and severe than is typically observed in individuals at a comparable level of development” (DSM-IV).¹ Inattention, hyperactivity, and impulsivity are commonly known as the core symptoms of attention deficit hyperactivity disorder. Symptoms must be present for at least six months, observed before seven years of age, and “clinically significant impairment in social, academic, or occupational functioning” must be evident in more than one setting. The symptoms must not be better explained by another disorder such as an anxiety disorder, mood disorder, psychosis, or autistic disorder.¹ The World Health Organization's International Statistical Classification of Diseases and Related Health Problems (ICD-10)² uses the term “hyperkinetic disorder” for a more restricted diagnosis. It differs from the DSM-IV classification³ because all three problems of attention, hyperactivity, and impulsiveness must be present, more stringent criteria for “pervasiveness” across situations must be met, and the presence of another disorder is an exclusion criterion.

Incidence/Prevalence

Prevalence estimates of ADHD vary according to the diagnostic criteria used and the population sampled. DSM-IV prevalence estimates among school children range from 3 to 5 percent,¹ but other estimates vary from 1.7 to 16 percent.^4,5 No objective test exists to confirm the diagnosis of ADHD, which remains a clinical diagnosis. Other conditions frequently coexist with ADHD. Oppositional defiant disorder is present in 35 percent (95 percent confidence interval [CI]: 27 to 44 percent) of children with ADHD, conduct disorder in 26 percent (95 percent CI: 13 to 41 percent), anxiety disorder in 26 percent (95 percent CI: 18 to 35 percent), and depressive disorder in 18 percent (95 percent CI: 11 to 27 percent).⁶

Etiology/Risk Factors

The underlying causes of ADHD are not known.⁶ There is limited evidence that it has a genetic component.^7–9 Risk factors also include psychosocial factors.¹⁰ There is increased risk in boys, compared with girls, with ratios varying from 3:1⁶ to 4:1.³

Prognosis

More than 70 percent of hyperactive children may continue to meet criteria for ADHD in adolescence, and up to 65 percent of adolescents may continue to meet criteria for ADHD in adulthood.⁵ Changes in diagnostic criteria cause difficulty with interpretation of the few outcome studies. One cohort of boys followed up for an average of 16 years found a ninefold increase in antisocial personality disorder and a fourfold increase in substance misuse disorder.⁷