Merck Manual

Please confirm that you are not located inside the Russian Federation

Loading

Attention-Deficit/Hyperactivity Disorder (ADHD)

By

Stephen Brian Sulkes

, MD, Golisano Children’s Hospital at Strong, University of Rochester School of Medicine and Dentistry

Last full review/revision May 2020| Content last modified May 2020
Click here for the Professional Version
GET THE QUICK FACTS
NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Topic Resources

Attention-deficit/hyperactivity disorder (ADHD) is poor or short attention span and/or excessive activity and impulsiveness inappropriate for the child’s age that interferes with functioning or development.

  • ADHD is a brain disorder that is present from birth or develops shortly after birth.

  • Some children mainly have difficulty with sustained attention, concentration, and ability to complete tasks; some children are overactive and impulsive; and some are both.

  • Doctors use questionnaires completed by parents and teachers as well as observations of the child to make the diagnosis.

  • Psychostimulant or other drugs plus structured environments, routines, a school intervention plan, and modified parenting techniques are often needed.

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder. Although children who have ADHD often behave in an overactive and impulsive way, ADHD is not a behavior disorder.

Although there is considerable controversy about the number of children affected, it is estimated that ADHD affects 8 to 11% of school-aged children and is twice as common among boys.

Many features of ADHD are often noticed before age 4 and invariably before age 12, but they may not interfere significantly with academic performance and social functioning until the middle school years.

ADHD was previously called just attention deficit disorder (ADD). However, the common occurrence of hyperactivity in affected children—which is really a physical extension of attention deficit and impulsivity—led to a change to the current terminology.

ADHD has three forms

  • Inattentive

  • Hyperactive/impulsive

  • Combined

The symptoms of ADHD range from mild to severe and can become exaggerated or become a problem in certain environments, such as at home or at school. The constraints of school and organized lifestyles make ADHD a problem, whereas in prior generations, the symptoms may not have interfered significantly with children’s functioning because people had different expectations about normal childhood behavior. Although some of the symptoms of ADHD can also occur in children without ADHD, they are more frequent and severe in children with ADHD.

Did You Know...

  • Hyperactivity in ADHD is really a physical extension of attention deficit and impulsivity.

ADHD in adults

Although ADHD is considered a disorder of children and always starts during childhood, it may not be recognized until adolescence or adulthood. The neurologic differences continue into adulthood, and about half of people continue to have behavior symptoms in adulthood.

In adults, symptoms include

  • Difficulty concentrating

  • Difficulty completing tasks (poor executive skills)

  • Restlessness

  • Mood swings

  • Impatience

  • Difficulty in maintaining relationships

ADHD can be more difficult to diagnose during adulthood. Symptoms may be similar to those of mental disorders, including mood disorders and anxiety disorders. Adults who abuse alcohol and recreational drugs may also have similar symptoms. Doctors ask adults to complete questionnaires to diagnose ADHD, but they may also need to review records from school to confirm a pattern of inattention or impulsivity.

Adults with ADHD may benefit from the same types of stimulant drugs as do affected children. They may also need counseling to help them improve their time management and develop other coping skills.

Causes

ADHD has no known single specific cause, but genetic (inherited) factors are often present. Research indicates that ADHD likely involves abnormalities in neurotransmitters (substances that transmit nerve impulses within the brain). Some other risk factors include low birth weight (under 3 pounds [1500 grams]), head injury, brain infection, iron deficiency, obstructive sleep apnea, and lead exposure, as well as exposure to alcohol, tobacco, or cocaine before birth.

Some people have raised concerns about whether food additives and sugar may cause ADHD. Although some children seem to become overactive or impulsive after eating foods containing sugar, studies have confirmed that the brain differences that lead to ADHD are present at birth and that food and environmental factors do not cause the disorder.

Symptoms

ADHD is primarily a problem with sustained attention, concentration, and task persistence (ability to finish a task). Affected children may also be overactive and impulsive. Preschool children with ADHD may have problems with communication and appear to have social interaction problems. As children reach school age, they may seem inattentive. They may fidget and squirm. They may be impulsive and talk out of turn. During later childhood, such children may move their legs restlessly, move and fidget their hands, talk impulsively, and forget easily, and they may be disorganized. They are generally not aggressive.

Signs of ADHD

All signs do not have to be present for a diagnosis of attention-deficit/hyperactivity disorder (ADHD). However, 6 or more signs of inattention or of hyperactivity and impulsivity must always be present for a diagnosis (or 6 from each group to diagnose the combined type of ADHD). Signs must be present in two or more situations (for example, at home and at school) and must interfere with social or academic functioning.

Signs of inattention:

  • Often fails to pay close attention to details

  • Has difficulty sustaining attention in work and play

  • Does not seem to listen when spoken to directly

  • Often does not follow through on instructions and fails to finish tasks

  • 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

  • Is easily distracted by extraneous stimuli

  • Is often forgetful

Signs of hyperactivity and impulsivity:

  • Often fidgets with hands or feet or squirms

  • Often leaves seat in classroom and elsewhere

  • Often runs about or climbs excessively

  • Has difficulty playing or engaging in leisure activities quietly

  • Is 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 waiting to take turns

  • Often interrupts or intrudes on others

About 20 to 60% of children with ADHD have learning disabilities affecting reading, math, or written language, and most have academic problems such as poor grades due to disorganization or incomplete homework (executive skills). Work may be messy, with careless mistakes and an absence of considered thought. Affected children often behave as if their mind is elsewhere and they are not listening. They often do not follow through on requests or complete schoolwork, chores, or other duties. There may be frequent shifts from one incomplete task to another.

Affected children may have issues with self-esteem, depression, anxiety, or opposition to authority by the time they reach adolescence. About 60% of young children have such problems as temper tantrums, and most older children have a low tolerance for frustration.

Diagnosis

  • A doctor's evaluation

The diagnosis of ADHD is based on the number, frequency, and severity of signs. Children must have 6 or more signs of inattention or of hyperactivity and impulsivity (or 6 from each group to diagnose the combined type of ADHD; see Signs of ADHD). Signs must be present in at least two separate environments (typically, home and school). Occurrence of signs just at home or just at school and nowhere else does not qualify as ADHD because such signs may be caused by the specific situation. Signs must also be more pronounced than would be expected for the child’s developmental level and must be present for 6 months or more. Often, diagnosis is difficult because it depends on the judgment of the observer. Also, children who are primarily inattentive may escape notice until their academic performance becomes adversely affected.

There is no laboratory test for ADHD. Questionnaires about various aspects of behavior and development can help doctors and psychologists make the diagnosis. Because learning disorders are common, many children receive psychologic testing both to help determine whether ADHD exists and to detect the presence of a specific learning disorder, either as a cause for inattention or as a coexisting problem.

A physical examination and sometimes various blood and other tests to rule out other disorders are also done.

ADHD: Epidemic or Over-Diagnosis?

An increasing number of children are diagnosed with attention-deficit/hyperactivity disorder (ADHD). However, there is concern among doctors and parents that many children are misdiagnosed. A high activity level may be completely normal and simply an exaggeration of normal childhood temperament. Alternatively, it may have a variety of causes, including emotional disorders or abnormalities of brain function, such as ADHD.

Generally, 2-year-olds are active and seldom stay still. A high activity and noise level is common up until age 4. In these age groups, and in children functioning developmentally in this age range, such behavior is normal. Active behavior can cause conflicts between parents and child and may worry parents. It also can create problems for others who supervise such children, including teachers.

Determining whether a child’s activity level is abnormally high should not simply depend on how tolerant the annoyed person is. However, some children are clearly more active than average. If the high activity level is combined with short attention span and impulsivity, it may be defined as hyperactivity and considered part of ADHD.

Scolding and punishing children for a high activity level usually backfires, increasing the child’s activity level. Avoiding situations in which the child has to sit still for a long time or finding a teacher skilled in coping with such children may help. If simple measures do not help, a medical or psychologic evaluation may be useful to rule out an underlying disorder such as ADHD.

Prognosis

Importantly, the vast majority of children with ADHD become creative and productive adults, and people who have ADHD may adjust better to work than to school situations. However, if the disorder is untreated in childhood, the risk of alcohol or substance abuse or suicide may increase.

Children with ADHD generally do not outgrow their inattentiveness, although children with hyperactivity tend to become somewhat less impulsive and hyperactive with age. However, most adolescents and adults learn to adapt to their inattentiveness. About one third of people find that they continue to benefit from the use of stimulant drugs.

Other problems that may emerge or persist in adolescence and adulthood include poor academic achievement, disorganization (known as poor executive skills), low self-esteem, anxiety, depression, and difficulty in learning appropriate social behaviors.

Treatment

  • Psychostimulant drugs

  • Behavior modification

Children are treated with both behavioral therapy and stimulant drugs. Drugs help to relieve symptoms and allow children to participate more easily in school and other activities. Younger children, especially, benefit from combination therapy. For preschool-aged children, behavioral therapy alone may be all that they need.

The federal Individuals with Disabilities Education Act (IDEA) requires public schools to provide free and appropriate education to children and adolescents with ADHD. Education must be provided in the least restrictive, most inclusive setting possible—that is, a setting in which the children have every opportunity to interact with nondisabled peers and have equal access to community resources. The Americans with Disability Act and Section 504 of the Rehabilitation Act also provide for accommodations in schools and other public settings.

Drug therapy

Psychostimulant drugs are the most effective drug treatment. Methylphenidate and other amphetamine-like drugs are the psychostimulants most often prescribed. They are equally effective and have similar side effects. A number of slow-release (longer-acting) preparations are available in addition to the regular forms and allow for once-daily dosing and may help to prevent inappropriate use.

Side effects of psychostimulant drugs may include

  • Sleep disturbances (such as insomnia)

  • Appetite suppression

  • Depression, sadness, or anxiety

  • Headaches

  • Stomachaches

  • Elevated heart rate and blood pressure

Most children have no side effects except perhaps a decreased appetite. All side effects disappear when the drug is stopped. However, when taken in large doses for a long time, stimulants can occasionally slow children’s growth, so doctors monitor weight and height. If children are growing slowly or have other significant side effects, doctors may advise drug holidays. A drug holiday is stopping the stimulant drug at times when children do not need to be as attentive and focused, for example on weekends or during the summer. However, some children have great difficulty functioning even outside of school and may not tolerate drug holidays.

A number of other drugs can be used to treat inattentiveness and behavioral symptoms. These drugs include

  • Atomoxetine (a nonstimulant ADHD drug)

  • Certain drugs typically used for high blood pressure such as clonidine and guanfacine

  • Antidepressants

  • Antianxiety drugs

Sometimes, a combination of drugs is used.

Behavior management

To minimize the effects of ADHD, structures, routines, a school intervention plan, and modified parenting techniques are often needed. Children without significant behavior challenges may benefit from drug treatment alone. However, stimulants do not work around the clock, so adaptations may be needed to help with organizational and other skills. Behavioral therapy conducted by a child psychologist is sometimes combined with drug treatment.

More Information

Drugs Mentioned In This Article

Generic Name Select Brand Names
CONCERTA, RITALIN
STRATTERA
TENEX
CATAPRES
NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Also of Interest

Videos

View All
Helping Babies Breathe at Birth
Video
Helping Babies Breathe at Birth
3D Models
View All
Cystic Fibrosis: Thickening Mucus
3D Model
Cystic Fibrosis: Thickening Mucus

SOCIAL MEDIA

TOP