Attention Deficit Hyperactivity Disorder: Overview and Risk Factors

Attention deficit hyperactivity disorder (ADHD) is characterized by difficulty maintaining attention, by hyperactivity and impulsive behavior, or by a combination of these symptom categories. It affects 5 to 10 percent of children, and up to 70 percent of cases continue into adolescence and adulthood. It may be associated with other psychiatric conditions, such as learning disabilities, anxiety, depression, and, later in life, substance abuse. About half of cases begin earlier than age 4.

The disorder is probably caused by a combination of genetic and environmental factors.

Risk Factors

• Male gender: ADHD appears to be two to three times more common in boys than in girls.
• Genetics: Some studies indicate that as much as 75 to 80 percent of risk may be genetic. Several genes have been identified as possible candidates.
• Environmental factors: Early lead exposure or head injury may increase the risk.

Diagnosis

For a diagnosis of ADHD, the American Psychiatric Association requires at least six symptoms of poor attention or at least six symptoms of hyperactivity and impulsive behavior, which are listed below. Symptoms must have lasted for at least six months, must have begun prior to age seven, and must be present in at least two settings (e.g., school and home). Also, there must be clear evidence of difficulty in social, academic, or workplace functioning.

Symptoms of poor attention:

• Often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
• Often has difficulty sustaining attention in tasks or at play.
• Often does not seem to listen when spoken to directly.
• Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace.
• Often has difficulty organizing tasks and activities.
• Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort.
• Often loses things necessary for tasks or activities.
• Often easily distracted.
• Often forgetful in daily activities.

Symptoms of hyperactivity and impulsive behavior:

• Often fidgets with hands or feet or squirms in seat.
• Often leaves seat in classroom or in other situations in which remaining seated is expected.
• Often runs about or climbs excessively in situations in which these behaviors are inappropriate.
• Often has difficulty playing or engaging in leisure activities quietly.
• Often "on the go" or acts as if "driven by a motor."
• Often talks excessively.
• Often blurts out answers before questions have been completed.
• Often has difficulty awaiting his or her turn.
• Often interrupts or intrudes on others (e.g., butts into conversations or games).

Treatment

• Stimulant medications are the most widely used treatment. Methylphenidate (Ritalin) and dextroamphetamine (Adderall) are effective in 60 to 70 percent of children with ADHD. Side effects may include decreased appetite, insomnia, anxiety, irritability, or headache. Recently, there has been concern over more serious side effects, including rare cases of death due to heart rhythm disturbances. However, further study is necessary.
• Non-stimulant medications may be effective, although studies of their effectiveness are limited. They are generally used in patients who do not respond to or cannot tolerate stimulant medications. Atomoxetine (Strattera) is the only Food and Drug Administration-approved non-stimulant for ADHD. The FDA has recently warned that this medication may cause liver damage.
• Other medications have been used in some patients. These include antidepressant medications (e.g., imipramine, nortriptyline, and bupropion) and clonidine. However, these medications are not yet approved by the FDA for use in ADHD.
• Behavioral interventions are useful for many patients, particularly children. These might include seating near the teacher, a daily report card with home reinforcement, and extended time to complete tasks.
• Replacing television viewing with exercise may be a promising preventive approach. A growing body of evidence indicates that small children who watch relatively little television have a significantly lower risk for developing ADHD, compared with other children. Physical activity in children plays an essential role in their growth and development. A review of studies found a significant decrease in disruptive behavior in children who exercised regularly, particularly those with ADHD. Also, sports and other social activities help children learn social skills appropriately.
• Biofeedback training may be a promising investigational treatment. Reports suggest that approximately 75 percent of patients have a positive clinical response.

Attention Deficit Hyperactivity Disorder: Nutritional Considerations

The role of diet in ADHD has been controversial ever since it was first proposed in the book Why Your Child Is Hyperactive, by pediatrician Ben Feingold, M.D. Dr. Feingold demonstrated that the removal of synthetic colorings, flavorings, and preservatives from the diet led to a significant improvement in many children. Subsequent studies suggested that the benefits of diet change may have been largely due to a placebo effect. However, continuing research has suggested that diet may indeed play a role in ADHD.

The following nutritional factors are under study for their effect on ADHD:

• Diets free of artificial flavorings, colors, and common allergens: At least eight studies have demonstrated significant behavioral improvement on low-allergen diets compared with regular diets. Typical low-allergen diets used in clinical studies have included only lamb, chicken, potatoes, rice, banana, apple, cabbage, cauliflower, Brussels sprouts, broccoli, cucumber, celery, carrots, parsnip, salt, pepper, calcium, and vitamins.
• Omega-3 fatty acids: Omega-3 fatty acids (found in fatty fish and various nuts and seeds, such as walnuts and flax seeds) have been reported to be lower in children with ADHD, compared with other children, suggesting that adding omega-3 fatty acids, either as foods or as supplements, may be beneficial. However, clinical trials of these fatty acids in children with ADHD have produced inconsistent results. Of six placebo-controlled studies, only three showed positive results.
• Zinc: Zinc influences several brain chemicals that may play roles in ADHD. Low zinc levels have been found in hyperactive children, compared with controls. Controlled clinical trials in the Middle East, an area of zinc deficiency, support the possibility that supplemental zinc (55 to 150 milligrams per day) may improve the response to stimulant medications or improve symptoms of hyperactivity and impulsive behavior when used alone. However, further controlled clinical trials are required.
• Sugar restriction: Controlled trials of sugar-restricted diets found no effect on behavioral symptoms, even in children thought to be sugar-sensitive.
• Aspartame restriction: Studies have not yet supported a role for aspartame (NutraSweet) in ADHD.
• Mineral supplements: Deficiency of several minerals (iron, copper, zinc, and calcium) may influence brain function, and several studies have demonstrated mineral deficiencies in children with ADHD. However, controlled studies have not established a clear benefit of supplementation in individuals with ADHD.