Attention-deficit/hyperactivity disorder (ADHD) is a syndrome of inattention, hyperactivity, and impulsivity. The 3 types of ADHD are predominantly inattentive, predominantly hyperactive-impulsive, and combined. Diagnosis is made by clinical criteria. Treatment usually includes drug therapy with stimulant drugs, behavioral therapy, and educational interventions.
ADHD has been classified as a developmental disorder, although some experts consider it a disruptive behavior disorder. ADHD affects an estimated 5 to 15% of school-aged children. However, many experts think ADHD is overdiagnosed, largely because criteria are applied inaccurately. According to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Text Revision (DSM-IV-TR), there are 3 types:
The predominantly hyperactive-impulsive type occurs 2 to 9 times more frequently in boys; the predominantly inattentive type occurs with about equal frequency in both sexes. ADHD tends to run in families.
ADHD has no known single, specific cause. Potential causes include genetic, biochemical, sensorimotor, physiologic, and behavioral factors. Some risk factors include birth weight < 1500 g, head trauma, and lead exposure, as well as prenatal exposure to alcohol, tobacco, and cocaine. Fewer than 5% of children with ADHD have other symptoms and signs of neurologic damage. Increasing evidence implicates abnormalities in dopaminergic and noradrenergic systems with decreased activity or stimulation in upper brain stem and frontal-midbrain tracts.
Symptoms and Signs
Onset often occurs before age 4 and invariably before age 7. The peak age for diagnosis is between ages 8 and 10; however, patients with the predominantly inattentive type may not be diagnosed until after adolescence.
Core symptoms and signs of ADHD involve
These symptoms (see Table 1: DSM-IV-TR Symptom Criteria for ADHD*) must be more pronounced than expected for the child's developmental level; impaired academic or social function is common.
Inattention tends to appear when a child is involved in tasks that require vigilance, rapid reaction time, visual and perceptual search, and systematic and sustained listening. Inattention and impulsivity impede development of academic skills and thinking and reasoning strategies, motivation for school, and adjustment to social demands. Children who have predominantly inattentive ADHD tend to be hands-on learners who have difficulty in passive learning situations that require continuous performance and task completion. Overall, about 20 to 60% of children with ADHD have learning disabilities, but some school dysfunction occurs in most children with ADHD.
Behavioral history can reveal low frustration tolerance, opposition, temper tantrums, aggressiveness, poor social skills and peer relationships, sleep disturbances, anxiety, dysphoria, depression, and mood swings.
Although there are no specific physical examination or laboratory findings associated with ADHD, signs can include
Diagnosis is clinical and is based on comprehensive medical, developmental, educational, and psychologic evaluations. Recently, the American Academy of Pediatrics has extended its recommendations for treatment of ADHD into the preschool age range (see ADHD: Clinical Practice Guideline for the Diagnosis, Evaluation, and Treatment of Attention-Deficit/Hyperactivity Disorder in Children and Adolescents).
DSM-IV-TR diagnostic criteria include 9 symptoms and signs of inattention, 6 of hyperactivity, and 3 of impulsivity (see Table 1: DSM-IV-TR Symptom Criteria for ADHD*); diagnosis using these criteria requires that symptoms and signs occur in at least 2 situations (eg, home and school) and be present before age 7. Diagnosis of the predominantly inattentive type requires at least 6 of the 9 possible symptoms and signs of inattention. Diagnosis of the hyperactive-impulsive type requires at least 6 of the 9 possible symptoms and signs of hyperactivity and impulsivity. Diagnosis of the combined type requires at least 6 symptoms and signs each of inattention and hyperactivity-impulsivity.
Differentiating between ADHD and other conditions can be challenging. Overdiagnosis must be avoided, and other conditions must be accurately identified. Many ADHD signs expressed during the preschool years could also indicate communication problems that can occur in other developmental disorders (eg, autism spectrum [pervasive developmental] disorders) or in certain learning disorders, anxiety, depression, or behavioral disorders (eg, conduct disorder). Clinicians should consider whether the child is distracted by external factors (ie, environmental input) or by internal factors (ie, thoughts, anxieties, worries). However, during later childhood, ADHD signs become more qualitatively distinct; children with the hyperactive-impulsive or combined types often exhibit continuous movement of the lower extremities, motor impersistence (eg, purposeless movement, fidgeting of hands), impulsive talking, and a seeming lack of awareness of their environment. Children with the predominantly inattentive type may have no physical signs.
Medical assessment focuses on identifying potentially treatable conditions that may contribute to or worsen symptoms and signs. Developmental assessment focuses on determining the onset and course of symptoms and signs. Educational assessment focuses on documenting core symptoms and signs; it may involve reviewing educational records and using rating scales or checklists. However, rating scales and checklists alone often cannot distinguish ADHD from other developmental disorders or from behavioral disorders.
|DSM-IV-TR Symptom Criteria for ADHD*
Does not pay attention to details
Has difficulty sustaining attention at school
Does not seem to listen when spoken to
Does not follow through on instructions or finish tasks
Has difficulty organizing tasks and activities
Avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort
Often loses things
Is easily distracted
Often fidgets with hands or feet or squirms
Often leaves seat in classroom or elsewhere
Often runs about or climbs excessively
Has difficulty playing quietly
Often on the go, acting as if driven by a motor
Often talks excessively
Often blurts out answers before questions are completed
Often has difficulty awaiting turn
Often interrupts or intrudes on others
*Diagnosis by DSM-IV-TR criteria requires that symptom criteria must be present in at least 2 situations and present before age 7. Diagnosis also requires the following:
≥ 6 of the 9 possible symptoms of inattention for the predominantly inattentive type
≥ 6 of the 9 possible symptoms of hyperactivity and impulsivity for the hyperactive-impulsive type
≥ 6 symptoms each of inattention and hyperactivity-impulsivity for the combined type
ADHD = attention-deficit/hyperactivity disorder; DSM-IV-TR = Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Text Revision.
Traditional classrooms and academic activities often exacerbate symptoms and signs in children with untreated or inadequately treated ADHD. Social and emotional adjustment problems may be persistent. Poor acceptance by peers and loneliness tend to increase with age and with the obvious display of symptoms. Substance abuse may result if ADHD is not identified and adequately treated because many adolescents and adults with ADHD self-medicate with both legal (eg, caffeine) and illegal (eg, cocaine) substances.
Although hyperactivity symptoms and signs tend to diminish with age, adolescents and adults may display residual difficulties. Predictors of poor outcomes in adolescence and adulthood include
Problems in adolescence and adulthood manifest predominantly as academic failure, low self-esteem, and difficulty learning appropriate social behavior. Adolescents and adults who have predominately impulsive ADHD may have an increased incidence of personality trait disorders and antisocial behavior; many continue to display impulsivity, restlessness, and poor social skills. People with ADHD seem to adjust better to work than to academic and home situations, particularly if they can find jobs that do not require intense attention to perform.
Randomized, controlled studies show behavioral therapy alone is less effective than therapy with stimulant drugs alone for school-aged children, but behavioral or combination therapy is recommended for younger children. Although correction of the underlying neurophysiologic differences of patients with ADHD does not occur with drug therapy, drugs are effective in alleviating ADHD symptoms and they permit participation in activities previously inaccessible because of poor attention and impulsivity. Drugs often interrupt the cycle of inappropriate behavior, enhancing behavioral and academic interventions, motivation, and self-esteem. Treatment of adults follows similar principles, but drug selection and dosing are determined on an individual basis, depending on other medical conditions.
Stimulant preparations that include methylphenidate or dextroamphetamine are most widely used. Response varies greatly, and dosage depends on the severity of the behavior and the child's ability to tolerate the drug. Dosing is adjusted in frequency and amount until the optimal response is achieved.
Methylphenidate is usually started at 0.3 mg/kg po once/day (immediate-release form) and increased in frequency weekly, usually to about tid or q 4 h. If response is inadequate but the drug is tolerated, dose can be increased. Most children find an optimal balance between benefits and adverse effects at individual doses between 0.3 and 0.6 mg/kg.
Dextroamphetamine is typically started (often in combination with racemic amphetamine) at 0.15 to 0.2 mg/kg po once/day, which can then be increased to bid, tid, or q 4 h. Individual doses in the range of 0.15 to 0.4 mg/kg are usually effective. Dose titration should balance effectiveness against adverse effects. In general, dextroamphetamine doses are about two thirds those of methylphenidate doses.
For methylphenidate or dextroamphetamine, once an optimal dosage is reached, an equivalent dosage of the same drug in a sustained-release form is often substituted to avoid the need for drug administration in school. Long-acting preparations include wax matrix slow-release tablets, biphasic capsules containing the equivalent of 2 doses, and osmotic release pills and transdermal patches that provide up to 12 h of coverage. Both short-acting and long-acting liquid preparations are now available. Pure dextro preparations (eg, dextromethylphenidate) are often used to minimize adverse effects such as anxiety; doses are typically half those of mixed preparations. Prodrug preparations are also sometimes used because of their smoother release, longer duration of action, fewer adverse effects, and lower abuse potential. Learning is often enhanced by low doses, but improvement in behavior often requires higher doses.
Dosing schedules of stimulant drugs can be adjusted to cover specific days and times (eg, during school hours, while doing homework). Drug holidays may be tried on weekends, on holidays, or during summer vacations. Placebo periods (for 5 to 10 school days to ensure reliability of observations) are recommended to determine whether the drugs are still needed.
Common adverse effects of stimulant drugs include
Some studies have shown slowing of growth over 2 yr of stimulant drug use, but results have not been consistent, and whether slowing persists over longer periods of use remains unclear. Some patients who are sensitive to stimulant drug effects appear overfocused or dulled; decreasing the stimulant drug dosage or trying a different drug may be helpful.
Atomoxetine, a selective norepinephrine reuptake inhibitor, is also used. The drug is effective, but data are mixed regarding its efficacy compared with stimulant drugs. Many children experience nausea, sedation, irritability, and temper tantrums; rarely, liver toxicity and suicidal ideation occur. A typical starting dose is 0.5 mg/kg po once/day, titrated weekly to 1.2 to 1.4 mg/kg once/day. The long half-life allows once/day dosing but requires continuous use to be effective. The maximum recommended daily dosage is 100 mg.
Antidepressants such as bupropion, α-2 agonists such as clonidine and guanfacine, and other psychoactive drugs are sometimes used in cases of stimulant drug ineffectiveness or unacceptable adverse effects, but they are less effective and are not recommended as first-line drugs. Pemoline is no longer available. Sometimes these drugs are used in combination with stimulants for synergistic effects; close monitoring for adverse effects is essential.
Counseling, including cognitive-behavioral therapy (eg, goal-setting, self-monitoring, modeling, role-playing), is often effective and helps children understand ADHD. Structure and routines are essential.
Classroom behavior is often improved by environmental control of noise and visual stimulation, appropriate task length, novelty, coaching, and teacher proximity.
When difficulties persist at home, parents should be encouraged to seek additional professional assistance and training in behavioral management techniques. Adding incentives and token rewards reinforces behavioral management and is often effective. Children with ADHD in whom hyperactivity and poor impulse control predominate are often helped at home when structure, consistent parenting techniques, and well-defined limits are established.
Elimination diets, megavitamin treatments, use of antioxidants or other compounds, and nutritional and biochemical interventions have had the least consistent effects. Biofeedback can be helpful in some cases but is not recommended for routine use because evidence of sustained benefit is lacking.
Last full review/revision March 2013 by Stephen Brian Sulkes, MD
Content last modified October 2013