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Attention-deficit/hyperactivity disorder
By Mayo Clinic staff
Overview
Attention-deficit/hyperactivity disorder (ADHD) is a group of chronic disorders that begin in childhood and sometimes last
into adult life. In general, children and adults with ADHD have a hard time paying attention and concentrating (inattention),
sitting still (hyperactivity) and controlling impulsive behavior (impulsivity). These problems can affect nearly every aspect
of life. Children and adults with ADHD often struggle with low self-esteem, troubled personal relationships and poor performance
in school or at work.
At various times, ADHD has been called attention-deficit disorder (ADD), hyperactivity, and even minimal brain dysfunction.
But today ADHD is the preferred term because it more accurately describes all aspects of the condition. Yet changing the name
hasn't made ADHD less controversial.
For some time, experts disagreed on how ADHD should be diagnosed — and even on whether it was a real disorder. But in
1998, the National Institute of Mental Health agreed that ADHD is a legitimate condition. In addition, most doctors believe
that a child shouldn't receive a diagnosis of ADHD unless the core symptoms of hyperactivity, impulsivity and inattention
have created significant problems at home and at school for at least 6 months. Even so, it often can be hard to distinguish
the behavior of a child with ADHD from that of normal, active children. And children who are either slow learners or bright,
quick learners and children with adjustment problems share many symptoms with ADHD children.
Just what constitutes the best treatment for ADHD is also a matter of debate. Currently, psychostimulant drugs such as methylphenidate
(Ritalin, Concerta) ordextroamphetamine (Dexedrine) are the most common treatment. But the use of these drugs is under scrutiny.
Psychostimulant medications can relieve many symptoms of ADHD, but they don't cure the disorder. It's also clear that counseling,
special accommodations in the classroom, and family and community support are just as, if not more, important in solving the
problems affecting a child's life.
Experts agree that without any treatment some children with ADHD will likely continue to have poor learning skills and low
self-esteem. They may also have social difficulties that last into adulthood. The good news is that when children receive
appropriate treatment for ADHD, their confidence, social skills and even academic performance may improve dramatically.
Signs and symptoms
The symptoms of ADHD fall into two broad categories: inattention and hyperactivity-impulsive behavior. In general, children
are said to have ADHD if they show six or more symptoms from each category for at least 6 months. These symptoms must affect
a child's ability to function to a large degree in at least two social settings — typically at home and at school. This
helps ensure that the problem isn't with a particular teacher or only with parents. Children who have problems in school but
get along well at home are not considered to have ADHD. In most children, symptoms appear between 4 and 6 years of age, although
they sometimes may occur earlier.
The signs and symptoms of ADHD include the following:
Inattention
Often fails to pay close attention to details or makes careless mistakes in schoolwork or other activities
Often has trouble sustaining attention during tasks or play
Often doesn't seem to listen when spoken to directly
Often doesn't follow through on instructions and fails to finish schoolwork, chores or other tasks
Often has difficulty organizing tasks or activities
Often avoids or dislikes tasks that require sustained mental effort, such as schoolwork or homework
Often loses things needed for tasks or activities, such as books, pencils, toys or tools
Is often easily distracted
Is often forgetful
Hyperactivity-impulsive behavior
Often fidgets with hands or feet or squirms in seat.
Often leaves seat in the classroom or in other situations where remaining seated is expected.
Often runs or climbs excessively when it's not appropriate. Adolescents might not run or climb but may constantly feel restless.
Often has difficulty playing quietly.
Is often "on the go" or acts as if "driven by a motor."
Often talks excessively.
Often blurts out the answers before questions have been completely asked.
Often has difficulty waiting his or her turn.
Often interrupts or intrudes on others by butting into conversations or games.
Most healthy children exhibit many of these behaviors at one time or another. For instance, parents may worry that a 3-year-old
who can't listen to a story from beginning to end or finish a drawing may have ADHD. But preschoolers normally have a short
attention span and aren't able to stick with one activity for long. This doesn't mean they're inattentive — it simply
means they're normal preschoolers.
Even in older children and adolescents, attention span often depends on the level of interest in a particular activity. Most
teenagers can listen to music or talk to their friends for hours but may be a lot less focused about homework.
The same is true of hyperactivity. Young children are naturally energetic — they often wear their parents out long before
they're worn out themselves. And they may become even more active when they're tired, hungry, anxious or in a new environment.
In addition, some children just naturally have a higher activity level than others.
When children have ADHD, however, they tend to be especially sensitive to stimuli such as sights, sounds and touch. When overstimulated,
they can quickly get out of control, becoming giddy and sometimes aggressive or even physically or verbally abusive. Children
with the inattentive form of ADHD may seem to drift away into their own thoughts or lose track of what's going on around them.
Most children with ADHD don't have all the signs and symptoms of the disorder. Furthermore, symptoms may be different in boys
and girls. Boys are more likely to be hyperactive, and girls tend to be inattentive. In addition, girls who have trouble paying
attention often daydream, but inattentive boys are more likely to play or fiddle aimlessly. Boys also tend to be less compliant
with teachers and other adults, so their behavior is often more conspicuous.
Sensory integration disorder
Symptoms of ADHD in adults
ADHD always begins in childhood, but it may last into adult life. The core symptoms of inattention, hyperactivity and impulsive
behavior are the same for adults as for children. Most adults have just one or two of the symptoms, not all three.
Adults who have problems with inattention may daydream during lectures or presentations at work and have trouble finishing
tasks. Hyperactive adults aren't likely to be as physically active as hyperactive children, but they may find it hard to sit
through movies or concerts or frequently shift positions or tap their fingers or feet. Impulsive adults often have trouble
waiting in line and driving in heavy traffic, and they may be tempted to take unnecessary risks. Adults with ADHD also may
have mood swings, a quick temper, a low tolerance for stress and problems with relationships.
Causes
Although the exact cause of ADHD isn't well understood, researchers have identified several factors that may play a role in
the disorder:
Altered brain function. The parts of the brain that regulate attention, planning and motor control seem to be less active
in children with ADHD. In addition, adults and children with ADHD appear to have low levels of dopamine — a brain chemical
with a number of important functions. Among other things, dopamine sends messages to the part of the brain that controls movement,
helps regulate attention and affects motivation. Some adults with ADHD have very low levels of the enzyme that produces dopamine
(dopa decarboxylase). Other people with ADHD seem to have too many dopamine transporters, which remove dopamine after it is
produced.
Heredity. ADHD tends to run in families. Most children with ADHD have at least one relative with the disorder, and approximately
one-third of men with a history of ADHD have children who also have ADHD. Furthermore, when one identical twin has ADHD, the
other twin almost always has the disorder as well.
Maternal smoking, drug use and exposure to toxins. Pregnant women who smoke are at increased risk of having children with
ADHD. And alcohol or drug abuse during pregnancy may reduce activity of the nerve cells (neurons) that produce dopamine. In
addition, pregnant women who are exposed to environmental poisons such as dioxins and PCBs are more likely to have children
with ADHD.
When to seek medical advice
In the 1990s, diagnosed cases of ADHD in the United States increased dramatically. The number of children with a diagnosis
of the disorder climbed from 950,000 in 1990 to more than 2.4 million in 1996, and the number of adults with a diagnosis of
ADHD more than tripled between 1992 and 1997. Some experts believe this increase is due, at least in part, to the intense
media coverage ADHD has received and to greater public awareness of the disorder.
The strong interest in ADHD likely means that more children with the disorder are receiving needed treatment. It may also
mean, however, that children who don't have ADHD or who have other problems such as depression, anxiety, learning disabilities
or sleep disorders are being diagnosed and treated incorrectly.
In general, if your child has trouble concentrating, sitting still or controlling his or her behavior, and these problems
are creating significant difficulties at home and at school, see your pediatrician or family physician. Your doctor may later
refer you to a specialist, such as a developmental-behavioral pediatrician, psychologist, psychiatrist or pediatric neurologist,
but it's important to have a medical evaluation first to rule out other causes of your child's symptoms.
Although symptoms of ADHD can sometimes appear in preschoolers, diagnosing the disorder in very young children is extremely
difficult. Often, developmental problems such as language delays and adjustment difficulties can be mistaken for ADHD. For
that reason, preschoolers suspected of having ADHD are more likely to need evaluation by a subspecialist.
Children being treated with medication should see their doctor regularly — typically every 6 months. Your doctor may
also recommend retesting every few years, depending on your child's grade level, age and diagnosis.
Call your physician if your child is taking medication for ADHD and experiences side effects, such as loss of appetite, trouble
sleeping or increased irritability. Over time some children taking stimulant medications may also lose weight. This is another
reason why follow-up visits are important.
Screening and diagnosis
No single test for ADHD exists, making the disorder difficult to diagnose. But a variety of exams can differentiate ADHD from
learning disabilities and mood disorders. For this reason, make sure that the physician performing the evaluation is well
trained and takes time to get background information from you and your child's teachers. Your physician should also make use
of appropriate local resources for needed testing. The process usually requires at least two office visits.
The following chart from the National Institute of Mental Health lists the types of doctors who are qualified to diagnose
and supervise treatment for ADHD
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