Risk Factors

In the U.S., the number of diagnosed cases of ADHD in children increased from 1990 to 1996, from nearly 950,000 to over 2.4 million. As of 2004, about 4.5 million children between the ages of 3 - 17 had been diagnosed at some point with ADHD. This accounts for 7.4% of all children in this age range.

ADHD is a genuine disorder, but it is telling that the U.S. accounts for 90% of worldwide prescriptions for stimulants for ADHD. It is not known whether this reflects a real increase in ADHD, or a better ability to recognize it. Some say it may be an indication of a culture that places excessive value on normalcy and academic achievement at the expense of more frequent diagnoses.

Gender and ADHD

ADHD is most often diagnosed in boys. However, there is some evidence that it is underdiagnosed in girls. Until recently, all major studies were conducted using boys as subjects. Important studies on girls with ADHD are now underway. A major study reported that girls with the condition experience the same multiple impairments as boys do.

Adults with ADHD

Although ADHD is primarily thought of as a childhood disorder, diagnoses of attention-deficit disorder in adults are on the rise. Methylphenidate (Ritalin) was prescribed for nearly 800,000 adults in the U.S. in 1997, nearly three times the number in 1992. As of 2005, experts estimated that ADHD affects about 4.1% of adults ages 18 - 44 years in a given year.

Attention Deficit Hyperactivity Disorder In Adults

Research suggests that ADHD affects between 2 - 6% of the adult population, assuming that one- to two-thirds of cases persist into adulthood. ADHD in adults always occurs as a continuum of the childhood condition. Adult-onset symptoms are likely to be due to other factors. Diagnosing adult ADHD can be a difficult problem since hyperactivity typically wanes as children get older, while attention and organizational problems may develop in older people. Some experts believe, then, that the number of adults with ADHD is underestimated.

• ?Inattention and memory problems. (Examples: losing or forgetting things, being absent-minded, not finishing things, misjudging time, depending on others for order, having trouble getting started, changing jobs or projects in the middle.)
• Hyperactivity and restlessness. (Examples: always being on the go, fidgety, easily bored, taking risks, liking active and fast paced jobs and activities, such as being a sales representative or stockbroker.)
• Impulsivity and emotional instability. (Examples: saying things without thinking first, interrupting others, being annoying to others, easily frustrated, easily angered, having unpredictable moods, driving recklessly, having high relationship and job turnover.)
• Problems with self worth. (Examples: Avoids new challenges, appears confident to others but not to oneself.)

Doctors use adult reports of their childhood behaviors and experiences when searching for clues for a diagnosis. Interestingly, the disorder seems to be distributed equally between adult women and men.

Accompanying Emotional, Personality, and Learning Disorders. Between 19 - 37% of adults with ADHD have depression or bipolar disorder. Between 25 - 50% have an anxiety disorder. Bipolar disorder plus ADHD, in fact, may be very difficult to differentiate from ADHD alone in adults.

Accompanying Learning Disorders. About 20% of adults with ADHD have learning disorders, usually dyslexia and auditory processing problems. These problems should be considered in any treatment plan.

Effect on Work. Compared to adults without ADHD, those with the condition tend to reach lower educational levels, earn less money, and be fired more often. In fact, one article reported that by the time they are in their 30s, about 35% of ADHD adults are self-employed.

Substance Abuse. According to a 2003 study, the incidence of ADHD is 5 - 10 times higher among alcoholics than in the general public. Other studies have reported that between 32 - 53% of adults with ADHD abuse alcohol, and between 8 - 32% smoke marijuana or take cocaine. An important 2003 study suggested that young people and adults most at risk for substance abuse were those who had inattention-related ADHD and conduct disorders as a child.

Sleep Disorders. Sleep disorders, especially restless legs syndrome and sleep apnea, are common in adults and children with ADHD. Sleep apnea is a disorder in which a person temporarily stops breathing during sleep, perhaps hundreds of times. In most cases the person is unaware of it, although sometimes they awaken and gasp for breath. It is usually accompanied by snoring. One report suggested that treating sleep apnea in adults with both conditions may help reduce ADHD symptoms.

Atomoxetine (Strattera). Atomoxetine (Strattera) is the first drug approved for adults with ADHD. It is a non-stimulant. In two well-conducted 2003 studies, atomoxetine significantly reduced symptoms of inattention, hyperactivity, and impulsivity in adult patients. Side effects were generally mild. However, several cases of atomoxetine-associated liver injury have been reported. As a result, the FDA has warned doctors that the drug should be discontinued at the first signs of jaundice or liver problems, and has asked the manufacturer to include a warning on its label. Although atomoxetine may increase the risk of suicidal thinking in children and adolescents, it does not appear to pose a risk for adults.

Antidepressants. Specific antidepressants, such as bupropion (Wellbutrin) and venlafaxine (Effexor), may be useful for adults with ADHD. Studies report response rates with these drugs of 50 - 78%. Bupropion may be a particularly good choice for certain ADHD adults, including those who also have bipolar disorder or a history of substance abuse. Tricyclic antidepressants, such as desipramine, may also be very effective, particularly in adults with both ADHD and depression.

Psychostimulants. The standard psychostimulants, methylphenidate (Ritalin) and Adderall, are also effective in adults. The newer, longer acting forms of methylphenidate (Concerta, Ritalin-LA, Metadate CD) and Adderall (Adderall XR) may offer further advantages.

Nicotine Replacement. Nicotine improves ADHD symptoms and appears to have effects in the brain that are similar to those of stimulants. Although such findings should certainly not encourage anyone to smoke, some studies are focusing on benefits of nicotine therapy in adults with ADHD.

Review Date: 12/21/2006
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital.

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