Attention deficit hyperactivity disorder (ADHD) is a chronic developmental disorder characterized by attention problems, including distractibility, hyperactivity, impulsive behaviors, and the inability to remain focused on tasks or activities. Typically diagnosed in childhood, the disorder can continue into adulthood. ADHD is called hyperkinetic disorder outside the United States.
ADHS is the most commonly diagnosed neurological disorder in children. Although childhood ADHD has been studied extensively, studies on adult ADHD have produced a wide range of conflicting results, in part because the hyperactive component of the disorder often becomes less noticeable as individuals mature and develop more self-control.
Three types of ADHD are recognized by the American Psychiatric Association, as outlined in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). These are:
- predominately hyperactive type, characterized by excessive physical activity (e.g., constant fidgeting, inability to stay seated, inability to engage in quiet play) and impulsive behaviors (e.g., interrupting, difficulty waiting in line)
- predominately inattentive type, characterized by an inability to pay close attention to detail, stay on task, and organize tasks; sometimes referred to as attention deficit disorder (ADD)
- combined hyperactive and inattentive type, characterized by an inappropriately high activity level with a high level of distractibility
ADHD is one of the most common mental disorders, with surveys suggesting that 5% of children and 2.5% of adults are affected. Diagnoses have increased in the late 1990s and early 2000s, with an ADHD label applied to up to 15% of all U.S. children under age 18 and up to 20% of all boys. Worldwide, estimates vary from less than 1% in the United Kingdom to 12% in some South American countries, depending on diagnostic criteria. ADHD is more common in boys than in girls.
ADHD may be diagnosed in children as young as three but is most often diagnosed in school-aged children who cause classroom disruptions or have difficulty completing their schoolwork. Although diagnostic criteria require that symptoms appear before age 12, two 2017 studies suggested that ADHD symptoms could first appear in early adulthood.
Causes and symptoms
Although the exact causes of ADHD are not known, it is clear that specific parts of the brain are involved, including the frontal cortex, parietal lobe, and possibly the cerebellum. Functional magnetic resonance imaging (fMRI) studies comparing the brains of children with ADHD and those without the disorder show that children with ADHD have weaker brain activation in the frontal area when responding to tasks that require inhibition. Researchers believe that this is related to an imbalance in certain neurotransmitters (the chemicals that carry signals between nerve cells), specifically deficits in the neurotransmitters dopamine and norepinephrine. Drugs used to treat ADHD make dopamine and/or norepinephrine more available in the brain.
ADHD appears to have a hereditary component. Three out of four children with ADHD have a relative with the disorder. Scientists have suggested at least 20 genes that may make an individual more susceptible to ADHD or contribute to the disorder in some way.
ADHD is more common in children whose mothers smoke tobacco, use drugs, or have been exposed to toxins. Pregnant women who smoke tobacco are at increased risk of giving birth to a child with ADHD. Alcohol or drug use or extreme stress during pregnancy also may increase risk of ADHD. Children exposed to toxins are more likely to acquire developmental and behavioral problems associated with ADHD. One such toxin that has been scientifically shown to produce ADHD-like symptoms is the element lead (symbol Pb), which is sometimes found in paint from old homes and buildings and in certain water systems, especially those with aged plumbing. Premature birth, low birth weight, or brain injury also may contribute to the development of ADHD.
A widely publicized study conducted by Benjamin F. Feingold (1899–1982) in the early 1970s suggested that allergies to certain foods and food additives cause the characteristic hyperactivity of children with ADHD. Although some children may have adverse reactions to certain foods that can affect their behavior (for example, a rash that temporarily distracts a child from other tasks), carefully controlled follow-up studies have uncovered no link between food allergies and ADHD. Likewise, there is no proven link between artificial food colorings or food preservatives and hyperactive behaviors of ADHD. A popularly held misconception is that sugar consumption causes hyperactive behaviors, but studies have found no link between sugar intake and ADHD. It is important to note, however, that a nutritionally balanced diet is important for normal development in all children.
Children with ADHD have short attention spans and become easily distracted or frustrated with tasks. Although they may be intelligent, their lack of focus frequently results in poor grades and difficulties in school. Children with ADHD act impulsively, taking action first and thinking later. They are constantly moving, running, climbing, squirming, and fidgeting, but they often have poor motor skills and may be clumsy and awkward. Clumsiness can extend to the social arena, where children are sometimes shunned due to their impulsive and intrusive behavior. Because of these symptoms, ADHD children are often troubled by low self-esteem and poor social relationships.
There is no single test for ADHD. Psychiatrists and other mental health professionals use the criteria listed in the DSM-5 as a guideline for diagnosing the disorder. An ADHD diagnosis requires the presence of at least six of the following symptoms of inattention or six or more symptoms of hyperactivity and impulsivity within the past six months (five symptoms in either category for those over age 17). These symptoms should be present in at least two different environments (e.g., home and school) and not be attributable to any other developmental or mental health disorder.
Signs of inattention include:
- fails to pay close attention to detail or makes careless mistakes in schoolwork or other activities
- has difficulty sustaining attention in tasks or activities
- does not appear to listen when spoken to
- does not follow through on instructions and does not finish tasks
- has difficulty organizing tasks and activities
- avoids or dislikes tasks that require sustained mental effort (e.g., homework)
- loses objects necessary for tasks (e.g., books, tools)
- is easily distracted
- is forgetful in daily activities
Signs of hyperactivity and impulsivity include:
- fidgets with hands or feet or squirms in seat
- does not remain seated or is restless when expected to sit
- runs or climbs excessively when inappropriate (feelings of restlessness in adolescents and adults)
- has difficulty playing quietly
- blurts out answers before questions have been completed
- has difficulty waiting (e.g., to take turns, to stand in line)
- interrupts and/or intrudes on others
Additional hyperactivity/impulsivity criteria include:
- acts without thinking, such as starting tasks without reading instructions or speaking without considering the consequences
- is impatient and acts restless when waiting for others
- is uncomfortable performing activities slowly, often rushing to complete tasks
- finds it difficult to resist temptations or opportunities, even when they involve risk
In the United States, public schools are required by federal law to offer free ADHD assessment upon request. A pediatrician can make an initial evaluation of one child's developmental maturity compared to other children in that child's age group and can provide a referral to a psychologist or pediatric psychiatrist for ADHD assessment. The physician also can perform a comprehensive physical examination to rule out organic causes of ADHD symptoms, such as an overactive thyroid, vision problems, or hearing problems. However, other problems, such as disciplinary issues, chaotic family life, or chronic boredom—as well as normal childhood rambunctiousness—can sometimes lead to a misdiagnosis of ADHD.
If an organic problem is not found, a psychologist, psychiatrist, neurologist, neuropsychologist, or learning specialist typically is consulted to perform a comprehensive ADHD assessment. A complete medical, family, social, psychiatric, and educational history is compiled from existing medical and school records and from interviews with parents and teachers. Interviews may also be conducted with the child, depending on the child's age. Along with these interviews, several clinical inventories may be used, such as the Conners Rating Scales (Teacher's Questionnaire and Parent's Questionnaire), Child Behavior Checklist (CBCL), and the Barkley Home Situation Questionnaire. These inventories provide valuable information on the child's behavior in different settings and situations. The Wender Utah Rating Scale has been adapted for use in diagnosing ADHD in adults. Continuous Performance Tests, which involve tasks performed on a computer, may support a diagnosis of attention-deficit type ADHD, but by themselves are not diagnostic.
A complete and comprehensive psychiatric assessment is critical to differentiate ADHD from other mood and behavioral disorders. As many as 50% to 60% of people diagnosed with ADHD also meet the diagnostic criteria for another major psychiatric disorder such as anxiety disorders, depression, antisocial personality disorder, oppositional defiant disorder, bipolar disorder, substance abuse disorder, or conduct disorder. There is a high likelihood that such individuals also have a learning disorder. Children with ADHD sometimes have Tourette syndrome, which is a neurological disorder characterized by vocal tics or compulsive muscle spasms.
Therapy that addresses both psychological and social issues (called psychosocial therapy), usually combined with medication, is the treatment approach of choice for alleviating ADHD symptoms, and in younger children, therapy is preferred over medication. The combination of therapy and medication has proven to be the most effective treatment approach to ADHD.
Drug therapy must be highly individualized with the benefits balanced against the risk of undesirable side effects. Generally, a child's response to medication changes with age and maturation, so ADHD symptoms must be monitored and prescriptions adjusted accordingly. Stimulant drugs, also known as psychostimulants, are considered the most effective medication for treating ADHD. These drugs generally increase the availability of neurotransmitters in the brain, which tends to reduce such symptoms as inattention, impulsivity, and hyperactivity. Dextroamphetamine (Dexedrine, Dextrostat), dextroamphetamine/amphetamine (Adderall), lisdexamfetamine (Vyvanse), methylphenidate (Concerta, Ritalin, Metadate, Daytrana patch), and dexmethylphenidate (Focalin) are common stimulant drug treatments. These drugs are available in both immediate-release and extended-release forms. In 2017, the U.S. Food and Drug Administration (FDA) approved an orally disintegrating extended-release formulation of methylphenidate (Contempla XR-ODT) for ADHD in children aged 6–17 and a long-acting amphetamine (Mydayis) for adults and children aged 13 and older.
Stimulants may have adverse side effects in some children. These can include loss of appetite, insomnia, mood disturbance, headache, and gastrointestinal distress. Tics may also appear and should be monitored carefully. Psychotic reactions are among the more severe side effects. There is some evidence that long-term use of stimulant medication may interfere with physical growth and weight gain. Some experts feel that these effects are ameliorated by taking medication breaks (so-called drug holidays) over school vacations or weekends. There are increasing concerns about long-term use of stimulant medications, and they are not recommended for children under age six.
Other drugs can be used to treat ADHD when stimulants are contraindicated or cause adverse side effects.
- Atomoxetine (Strattera) is a non-stimulant norepinephrine reuptake inhibitor that increases the availability of norepinephrine.
- Guanfacine (Intuniv, Tenex) and clonidine (Catapres, Kapvay) are systemic antihypertensive (blood-pressure-lowering) medications that are also used for ADHD.
- Antidepressants such as bupropion (Wellbutrin, others), although not specifically approved for ADHD, may be used alone or in combination with stimulants, especially in patients with another coexisting mental disorder. Atomoxetine and antidepressants may take several weeks to reach their full effectiveness.
Behavior therapy is used alone or in conjunction with drug therapy for ADHD and is recommended before medication for young children.
- Behavior modification uses a reward system to reinforce good behavior and task completion and can be implemented both in the classroom and at home. A tangible reward, such as a sticker, may be given to the child every time the child completes a task or behaves in an acceptable manner. A chart system can be used to display the stickers and visually illustrate the child's progress. When a certain number of stickers are collected, the child may trade them in for a bigger reward such as a trip to the zoo or a day at the beach. The reward system stays in place until the good behavior becomes ingrained and is sustained without reward.
A variation of behavior therapy, cognitive-behavioral therapy, works to decrease impulsive behavior by helping the child recognize the connection between thoughts and behavior. Behavior is changed by altering negative thinking patterns.
Individual psychotherapy may help children with ADHD build self-esteem, give them a place to discuss their worries and anxieties, and help them gain insight into their behavior and feelings.
- Social skills training can help children learn more appropriate behaviors when interacting with others.
Family therapy can be beneficial in helping family members develop coping skills and work through feelings of guilt or anger that they may be experiencing. Families frequently need help coping with the demands and challenges of ADHD. The symptoms of inattention, shifting activities every few minutes, difficulty completing homework and household tasks, losing objects, interrupting, not listening, rule breaking, constant talking, boredom, and irritability can take a toll on other family members.
- Parenting skills training can help parents to develop methods for better understanding and dealing with their children.
Support groups can provide much needed networks for information, education, and other types of help for children and their families. Support groups for families are increasingly available through school districts and health-care providers. Community colleges frequently offer courses in discipline and behavior management. There also are a number of popular books on living with ADHD.
Children with ADHD should have an individual educational plan (IEP) that outlines modifications to the regular mode of instruction for facilitating learning. Teachers must consider the needs of these children when giving instructions, making sure that the instructions are appropriately paced. Teachers must also understand the origins of impulsive behavior—that these individuals are not deliberately trying to ruin a lesson or activity by acting unruly. Teachers should teach in a structured manner, be comfortable with the remedial services some children may need, and be able to maintain good lines of communication with the parents.
Educational specialists devise a series of compensatory strategies for enabling these children to cope with their attention deficit or hyperactivity. These strategies might include simple strategies such as creating checklists of steps to complete before handing in assignments (name on top, check spelling, etc.), putting a clock on the child's desk to help structure time for activities, or covering the pictures on a page to prevent distractions while the child is reading the words.
There are a number of alternative treatments for ADHD. Regular exercise, in combination with other treatments, has been shown to have a positive effect on behavior in children with ADHD and can improve attention and focus. The American Academy of Pediatrics has recognized electroencephalography (EEG) biofeedback, also called neurofeedback training, as being as effective as medication for treating symptoms of ADHD and ADD. EEG biofeedback trains patients to generate brainwave activity associated with calm focus and attention. Sound or music therapies are also used to retrain the brain.
Other popular alternative treatments do not meet safety and effectiveness standards required by conventional medicine. However, proponents report that the following may help control symptoms in some ADHD patients.
- Dietary therapy. Based in part on the Feingold food allergy diet, dietary therapy focuses on a nutritional plan that is high in protein and complex carbohydrates and free of white sugar and salicylate-containing foods such as strawberries, tomatoes, and grapes. Other recommended diets eliminate potential allergens such as wheat, milk, and eggs or artificial food colorings and additives. Essential fatty acids, including omega-3 oils, have been studied for possible benefits. Zinc supplementation has shown positive results in alleviating symptoms of hyperactivity, impulsiveness, and social interaction problems, although additional research was needed as of 2017.
- Herbal therapy. Herbal therapy uses a variety of natural remedies to address the symptoms of ADHD, including ginkgo (Ginkgo biloba) for memory and mental sharpness and chamomile (Matricaria recutita) extract for calming. There is no evidence that herbal supplements help with ADHD. They are not regulated and may not be safe.
- Proprietary formulations marketed for ADHD are of unproven effectiveness and potentially harmful.
- Homeopathic medicine. The theory of homeopathic medicine is to treat the whole person at a core level. Constitutional homeopathic care requires consulting a well-trained homeopath who has experience working with ADD and ADHD.
- Yoga and/or meditation. Regular practice of yoga or medication and relaxation techniques may calm children and help them acquire discipline.
Most children who receive therapy for ADHD develop into normally functioning adults. Approximately 70% to 80% of ADHD patients treated with stimulant medication experience significant relief from symptoms, at least in the short term. Some children with ADHD outgrow their symptoms in adolescence or early adulthood, whereas others retain some or all of their symptoms as adults. Some children diagnosed with ADHD develop conduct disorder. As many as 25% of adolescents with both ADHD and conduct disorder go on to develop antisocial personality disorder, criminal behavior, and/or substance abuse, with a high rate of suicide attempts that frequently accompany psychiatric disorders.
Untreated ADHD negatively affects a child's social and educational performance and can seriously damage the child's sense of self-esteem. Children with ADHD may have impaired relationships with their peers and be looked upon as social outcasts. They may be perceived as slow learners or troublemakers in the classroom. Siblings and even parents may develop resentful feelings toward a child with ADHD. Parents may not understand how attention lapses or impulsivity affect daily functioning, and they may not be trained in techniques that help children with ADHD manage their behavior. Siblings may be resentful of what the child seems to get away with or the inordinate amount of attention that sibling receives. The child with ADHD may be resentful of a younger sibling who is more accomplished at school or never seems to get into trouble. Family interaction patterns may set up vicious cycles that become destructive and difficult to break.
There is no known way to prevent ADHD. However, pregnant women should avoid the use of alcohol, drugs, and tobacco products to prevent potential problems in their children.