Attention deficit hyperactivity disorder (ADHD)

DEFINITION: Attention deficit hyperactivity disorder (ADHD) is a condition characterized by an inability to focus attention or to inhibit impulsive, hyperactive behavior; it is associated with behavior that results in poor performance in educational, social, or work settings. The disorder is typically diagnosed in childhood, but symptoms can persist into adulthood for some people.

ALSO KNOWN AS: Attention-deficit hyperactivity disorder (ADHD); attention deficit/hyperactivity disorder (ADHD); attention-deficit disorder (ADD)

ANATOMY OR SYSTEM AFFECTED: Brain, nervous system, psychic-emotional system

CAUSES: Unknown, possibly genetic

SYMPTOMS: Inattention, hyperactivity, impulsiveness, fidgeting

DURATION: Chronic

TREATMENTS: Behavioral therapy, counseling, medications

Overview

"Attention-deficit disorder (ADD) with or without hyperactivity" was first defined in the third edition of the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (1980), or DSM-III. Its definition has evolved since then. The name ADD was changed to attention deficit hyperactivity disorder (ADHD) in the revised edition of the DSM-III-R (1987). In 1998, the National Institutes of Health (NIH) held a Consensus Development Conference on the Diagnosis and Treatment of Attention Deficit Hyperactivity Disorder. While most experts supported the ADHD diagnosis criteria, the final report noted a need for further research into the validity of the diagnosis. The DSM-5, a revised version of which was published in 2023, updated the definition of ADHD to reflect the growing body of evidence that shows the condition can last beyond childhood in order to help clinicians diagnose and treat adults with ADHD. A 2021 study published in the American Journal of Psychiatry found that about 90 percent of children with ADHD continued to experience some form of ADHD into early adulthood. About 30 percent of the children studied did experience full remission into adulthood, but of those, 60 percent had a recurrence of the condition some point after the initial remission.

The prevalence of ADHD among the general population is difficult to determine, and depends largely on the diagnostic criteria used and the population studied. The APA, in the DSM-5, states that around 5 percent of children have ADHD, while a national parent survey conducted by the Centers for Disease Control and Prevention (CDC) from 2020 to 2022 found that around 11.3 percent of children, or about six million, in the United States had ever been diagnosed with the disorder. According to a 2024 factsheet by Forbes Health, ADHD may affect an estimated 129 million children from the ages of three to seventeen. About 8.7 million adults in the US are living with ADHD, and a total of approximately 139.8 million adults worldwide.

Causes and Symptoms

The causes of ADHD are unknown, although the fact that it often occurs in families suggests some degree of genetic inheritance. First-degree relatives of patients with ADHD are two to eight times more likely to develop ADHD than a person who has no first-degree relatives with ADHD. Boys are two times more likely to be affected than girls, although studies have shown that girls are likely underdiagnosed because their symptoms manifest differently. ADHD is usually diagnosed when a child enters school, but it may be discovered earlier. According to the DSM-5, several of an individual's symptoms must be present prior to age twelve to merit a diagnosis of ADHD.

The pathophysiologic basis for ADHD is thought to be abnormalities in the dopaminergic and noradrenergic neurotransmission systems. Some genetic causes of ADHD that have been suggested include a possible mutation of the dopamine D4 receptor gene (DRD4) or a phenotypic variation in the catechol-O-methyltransferase gene (COMT). Other risk factors being explored include head injury before the age of two years; exposure to emotionally traumatic situations, such as abuse, neglect, or violence; and childhood exposure to environmental contaminants such as lead and organophosphate pesticides, substances such as alcohol and nicotine in utero, or secondhand smoke in childhood. Some studies have suggested that a high level of television viewing between the ages of one and three years may be modestly associated with ADHD. Other studies suggest that food dyes and preservatives such as artificial colors or sodium benzoate may increase hyperactivity. Other possible factors that may increase the risk of ADHD include maternal urinary tract infection during pregnancy, premature birth, complex congenital heart disease, fragile X syndrome, and Turner syndrome.

Individuals who do not have ADHD may at times display some of the symptoms of this disorder, but those who are diagnosed with ADHD must display symptoms most of the time and across multiple settings—in school, at home, and during other activities. According to the DSM-5, a child must display six or more ADHD symptoms for six months or longer to be diagnosed with the disorder, while adults must display five or more symptoms to be eligible for diagnosis. Prior to diagnosis, the referring pediatrician and specialist should rule out any undetected hearing or vision problems, any learning disabilities, undetected seizures, and anxiety and depression that may be causing ADHD-like symptoms.

The symptoms of ADHD are usually grouped into three main categories: inattention, hyperactivity, and impulsiveness. Individuals who have symptoms of inattention often make mistakes or do not pay close attention to details in school, social settings, or at work. They may have problems sustaining attention over time and frequently do not seem to listen when spoken to, especially in groups. Individuals with ADHD have difficulty following instructions and often fail to finish chores or schoolwork. They do not organize well and may have messy rooms and desks at school. They also frequently lose things necessary for school, work, or other activities. Because they have trouble sustaining attention, some individuals with ADHD dislike tasks that require this skill and will try to avoid them. One of the key symptoms is distractibility, which means that people with ADHD are often paying attention to extraneous sights, sounds, smells, and thoughts rather than focusing on the task at hand. ADHD may also be characterized by forgetfulness in daily activities, despite numerous reminders about such common, everyday activities as dressing, hygiene, manners, and other behaviors. People with ADHD may seem to have a poor sense of time; they are frequently late or think that they have more time to do a task than they really do.

Not all individuals with ADHD have symptoms of hyperactivity, but many have problems with fidgeting or squirming. It is common for these individuals to be constant talkers, often interrupting others. Other symptoms of hyperactivity include leaving their seat in school, work, or similar settings and moving around excessively in situations where they should be still. Some people with ADHD seem to be driven by a motor or are continuously on the go.

Individuals with ADHD may also have some symptoms of impulsiveness, such as blurting out answers before questions are completed. Another example of impulsiveness would be interrupting or intruding upon others in conversation or in some activity. They may also have difficulty standing in lines or waiting for their turn.

It is important to recognize that children with ADHD are not bad children who are hyperactive, impulsive, and/or inattentive on purpose. Rather, they are usually bright children who would like to behave better and to be more successful in school, in social life with peers, and in family affairs, but they simply cannot. One way to think about ADHD is to consider it a disorder of the ability to inhibit impulsive, off-task, or undesirable attention. Consequently, an individual with ADHD cannot separate important from unimportant stimuli and cannot sort appropriate from inappropriate responses to those stimuli. It is easy to understand how someone whose brain is trying to respond to a multitude of stimuli, rather than sorting stimuli into priorities for response, will have difficulty focusing and maintaining attention to the main task.

Individuals with ADHD may also have a short attention span, particularly for activities that are not perceived to be fun or entertaining. They will be unable to concentrate because they will be distracted by peripheral stimuli. They may also have poor impulse control so that they seem to act on the spur of the moment. They may be hyperactive or clumsy, resulting in their being labeled “accident-prone.” In fact, several cross-sectional studies have found that individuals with ADHD face an increased risk of injury compared to individuals without ADHD. They may also have problems completing tasks that require a lot of organization and planning—often first seen when the individual is in the third grade or beyond. They may display attention-demanding behavior and/or show resistant or overpowering social behaviors. Last, children with ADHD often act as if they were younger than they are, and “immaturity” is a frequent label. Along with this trait, they are susceptible to mood swings and are often seen as emotional.

Twenty-first-century scholarship on ADHD has debated whether the fact that ADHD is twice as likely to be diagnosed in boys is indicative of an underdiagnosis of ADHD in girls. A 2019 study published in Psychiatry Research argued that gender stereotypes in the way in which ADHD symptoms are professionally understood has led to a differing rate of diagnosis between boys and girls. The results of the study suggested that ADHD is less common in girls due to the fact that girls are more likely to present less-visible inattentive symptoms, while boys are more likely to present highly visible hyperactive symptoms. Studies on ADHD have historically focused on the more visible hyperactive symptoms of ADHD, which caused those who present predominately inattentive symptoms to receive less attention. Additionally, the study found that diagnosed girls had more ADHD-related problems and symptoms than diagnosed boys, which suggests a higher threshold that girls must meet medically before being diagnosed by a physician. The study called for more accurate screening methods and a better understanding of how ADHD manifests in girls in order to more accurately diagnose ADHD among girls.

Many experts think that ADHD may be related to problems with brain development. Studies have shown that the prefrontal cortex, striatum, and cerebellum in the brains of individuals with ADHD are less activated on functional magnetic resonance imaging (fMRI) than age-matched controls without ADHD. These regions of the brain are rich in dopaminergic and noradrenergic pathways and are associated with executive function. Other researchers have hypothesized that a developmental abnormality of the inferior frontal gyrus (cerebral cortex ridge) might cause the inhibition difficulties seen in ADHD.

Hyperactive symptoms may improve in adolescence, although adolescents with ADHD may continue to have problems with impulsive behavior and inattention. They may have considerable difficulty complying with rules and following directions. They may be poorly organized, causing problems with both starting projects and completing them. Adolescents with ADHD may have problems in school in spite of average or above-average potential. They may have poor self-esteem and a low frustration tolerance. Because of these and other factors related to ADHD, they may also be at greater risk of developing substance use problems and other mental health problems. ADHD may also persist into adulthood, in which case it is referred to as adult ADHD. The same diagnostic criteria apply, including the presence of the disorder since childhood.

Several other neurologic or psychiatric disorders have symptoms that can overlap with ADHD, so accurate diagnosis can be difficult. When an individual is suspected of having ADHD, they should have a thorough medical interview and a physical examination conducted by a physician familiar with child development, ADHD, and related conditions. A psychological evaluation to determine intelligence quotient (IQ) and areas of learning and performance strengths and weaknesses should be obtained. The evaluation should include an assessment for common coexisting conditions, such as learning disabilities. A thorough family history and a discussion of family problems such as divorce, violence, alcoholism, or drug abuse should be part of the evaluation, as symptoms of ADHD may arise after a significant and sudden change in a child's life. Conditions that may present similar symptoms to ADHD include psychological disturbances caused by abuse or neglect, bullying, social skills deficits, or an improper learning environment. Other conditions that might be found to exist along with ADHD, or to be the underlying cause of symptoms thought to be ADHD, include oppositional defiant disorder, conduct disorder (usually seen in older children), depression, anxiety, or a substance abuse disorder.

Treatment and Therapy

Treatment and therapy for ADHD will usually begin with the diagnostic process. Generally, treatment will begin with some combination of counseling, education, and behavioral therapy. Behavioral therapy may be administered by a parent, teacher, or counselor. In some cases, family counseling may be indicated. This counseling may be help family members learn about ADHD. Parent training interventions may help to improve some symptoms of ADHD in children. Family counseling also may be recommended when family issues are thought to be related to the type or severity of symptoms that the child may be experiencing. For instance, if the family is undergoing a stressful event, such as a divorce, serious loss, or death, or other problems such as economic stress, then the symptoms of ADHD may worsen. Therefore, treatment may focus on trying to minimize the impact of such stressors on the child. In addition, neurofeedback may reduce inattentive behaviors and impulsivity.

If behavioral and nonpharmacologic interventions do not lead to improvement, and if there is a moderate to severe functional disturbance caused by ADHD, medications may be considered. Stimulants have the best evidence for the treatment of ADHD; stimulant medications include methylphenidate (Ritalin), extended-release dexmethylphenidate (Focalin), and amphetamines (Adderall). These medications are generally thought to be safe and effective, although they can have such adverse effects as headache, stomachache, mood changes, heart-rate changes, appetite suppression, and interference with falling asleep. All children receiving medication must be monitored at regular intervals by a physician.

Nonstimulant medications are the second-line pharmacological treatment of ADHD, especially if stimulant medications are ineffective or poorly tolerated. Other medications that may be used for ADHD include atomoxetine (Strattera), antidepressants such as desipramine or bupropion, and alpha-2 adrenergic agonists such as clonidine and extended-release guanfacine.

Costs and risks for adverse effects should be discussed with the physician who has made the diagnosis of ADHD before implementing any treatment, to ensure safety and a reasonable expectation of efficacy.

The COVID-19 pandemic that began in 2020 interfered with the diagnosis of ADHD in children. With the onset of the pandemic and the cancellation of in-person medical visits, many children of the age when ADHD is commonly diagnosed were deprived of the tools and resources needed for diagnosis. For children already diagnosed with ADHD, the pandemic worsened some of the effects of the condition. Contributing factors included the interruption of routines, the challenges of remote learning, and the added stress and pressures of the pandemic.

Perspective and Prospects

Attention deficit hyperactivity disorder remains controversial due to the subjective nature of its symptoms and the possible overdiagnosis and overtreatment of the disorder. Historically, experts have estimated that ADHD affects between 2 and 10 percent of the general population. From 2020 to 2022, data from the CDC showed that approximately 11.3 percent of children in the US between the ages of five and seventeen have been diagnosed with ADHD. In 2024, the worldwide prevalance of ADHD was estimated at 5 percent of children and adults. This followed a general increase in rates of diagnosis beginning in the 1970s. ADHD experts cautioned against attributing the increase to a single factor, including misdiagnosis and increased pharmacological treatment of milder forms of the disorder.

Despite the availability of treatments and strategies to help individuals deal with ADHD, the condition can contribute to lifelong challenges for some individuals, including interpersonal relationship issues, unemployment, and other negative outcomes. Some of these challenges can be life-threatening; for example, adults with ADHD are more likely than those without ADHD to struggle with substance abuse issues and die by suicide. However, the responsiveness of ADHD to treatment can make it less likely for people living with ADHD to experience these outcomes. For example, a study published in 2022 found that individuals diagnosed with ADHD who took medication were 18 percent less likely to experience unemployment compared to adults with ADHD who did not take medication.

Many experts also suggest that shifts in how ADHD is diagnosed, increasing tendencies to prescribe medications, and a rise in public awareness and media attention have all contributed to an increase in diagnoses, if not an increase in actual cases. These trends have also led some researchers to warn against overdiagnosis of ADHD, cautioning that not all children with high energy or difficulty focusing necessarily have the disorder, especially at very young ages. Some even challenge the concept of ADHD altogether, claiming that it is a case of applying a medical diagnosis to a range of behaviors that may go against social norms but have historically not been seen as a medical issue. Still, the majority of medical professionals do recognize ADHD as a legitimate condition, if one surrounded by continued controversies and misunderstandings.

For individuals with ADHD, the disorder is a real issue that can cause great harm and impairment if not recognized and managed correctly. Diagnosis should be based on family history, careful examination, and thorough psychological assessment. Treatment should always begin with behavioral interventions before medication.

Individuals with ADHD can share experiences and resources through organizations that assist families dealing with attention deficit hyperactivity disorder. The US organization Children and Adults with Attention Deficit/Hyperactivity Disorder (CHADD) has state and local chapters helping individuals and families cope with the condition. CHADD chapters often have libraries and provide resources on ADHD management. The Learning Disabilities Association of America (LDA) also has state and local chapters helping schools and families cope with a wide range of learning disabilities, including ADHD.

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