Attention Deficit/Hyperactivity Disorder

Learning Objectives

  • Describe the symptoms, risk factors, influences, and prevalence of attention deficit/hyperactivity disorder

Attention Deficit/Hyperactivity Disorder

Diego is always active, from the time he wakes up in the morning until the time he goes to bed at night. His mother reports that he came out the womb kicking and screaming, and he has not stopped moving since. He has a sweet disposition, but always seems to be in trouble with his teachers, parents, and after-school program counselors. Diego seems to accidentally break things constantly, he lost his jacket three times last winter, and he never seems to sit still. His teachers believe Diego is a smart child, but he never finishes anything he starts and is so impulsive that he does not seem to learn much in school.

Diego likely has attention deficit/hyperactivity disorder (ADHD). The symptoms of this disorder were first described by Hans Hoffman in the 1920s. While taking care of his son while his wife was in the hospital giving birth to a second child, Hoffman noticed that the boy had trouble concentrating on his homework, had a short attention span, and had to repeatedly go over easy homework to learn the material (Jellinek & Herzog, 1999). Later, it was discovered that many hyperactive children—those who are fidgety, restless, socially disruptive, and have trouble with impulse control—also display short attention spans, problems with concentration, and distractibility. By the 1970s, it had become clear that many children who display attention problems often also exhibit signs of hyperactivity. In recognition of such findings, the DSM-3 (published in 1980) included a new disorder: attention deficit disorder with and without hyperactivity, now known as attention deficit/hyperactivity disorder (ADHD).

A child with attention deficit/hyperactivity disorder (ADHD) shows a constant pattern of inattention and/or hyperactive and impulsive behavior that interferes with normal functioning (APA, 2013). Some of the signs of inattention include great difficulty with and avoidance of tasks that require sustained attention (such as conversations or reading), failure to follow instructions (often resulting in failure to complete schoolwork and other duties), disorganization (difficulty keeping things in order, poor time management, and sloppy and messy work), lack of attention to detail, becoming easily distracted, and forgetfulness. Hyperactivity is characterized by excessive movement and includes fidgeting or squirming, leaving one’s seat in situations when remaining seated is expected, having trouble sitting still (e.g., in a restaurant), running about and climbing on things, blurting out responses before another person’s question or statement has been completed, difficulty waiting one’s turn for something, and interrupting and intruding on others. Frequently, the hyperactive child comes across as noisy and boisterous. The child’s behavior is hasty, impulsive, and seems to occur without much forethought; these characteristics may explain why adolescents and young adults diagnosed with ADHD receive more traffic tickets and have more automobile accidents than do others (Thompson, Molina, Pelham, & Gnagy, 2007).

ADHD occurs in about 5% of children (APA, 2013). On the average, boys are three times more likely to have ADHD than are girls; however, such findings might reflect the greater propensity of boys to engage in aggressive and antisocial behavior and thus incur a greater likelihood of being referred to psychological clinics (Barkley, 2006). This may also be reflective of bias in failing to appropriately diagnose girls and women who show symptoms. Children with ADHD face severe academic and social challenges. Compared to their non-ADHD counterparts, children with ADHD have lower grades and standardized test scores and higher rates of expulsion, grade retention, and dropping out (Loe & Feldman, 2007). They also are less well-liked and more often rejected by their peers (Hoza et al., 2005).

Previously, ADHD was thought to fade away by adolescence. However, longitudinal studies have suggested that ADHD is a chronic problem, one that can persist into adolescence and adulthood (Barkley, Fischer, Smallish, & Fletcher, 2002). A recent study found that 29.3% of adults who had been diagnosed with ADHD decades earlier still showed symptoms (Barbaresi et al., 2013). Somewhat troubling, this study also reported that nearly 81% of those whose ADHD persisted into adulthood had experienced at least one other comorbid disorder compared to 47% of those whose ADHD did not persist.

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Watch this for an overview of ADHD, from diagnostic criteria to possible underlying causes and types of treatment:

You can view the transcript for “Attention deficit hyperactivity disorder (ADHD/ADD) – causes, symptoms & pathology” here (opens in new window).

For an optional video on what it’s like living with ADHD, click here to watch this TED talk by Toby Shaw.

Case Studies: What is hyperactivity?

Case 1: Michael

Michael, a four-year-old boy, was referred to a child psychologist to be evaluated for ADHD. His parents reported that Michael would not comply with their instructions. They also complained that Michael would not remain seated during “quality time” with his father. The evaluating psychologist interviewed the family, and, by all accounts, Michael was noncompliant and often left his seat. Specifically, when Michael’s mother asked him to prepare his preschool lunch, Michael would leave the kitchen and play with his toys soon after opening his lunch box. Further, the psychologist found that “quality time” involved Michael and his father sitting down for several hours to watch movies. In other settings, such as preschool, Michael was compliant with his teacher’s requests and no more active than his peers.

In this case, Michael’s parents held unrealistic expectations for a child at Michael’s developmental level. The psychologist would likely educate Michael’s parents about normative child development rather than diagnosing Michael with ADHD.


Case 2: Jake

Jake, a 10-year-old boy, was referred to the same psychologist as Michael. Jake’s mother was concerned because Jake was not getting ready for school on time. Jake also had trouble remaining seated during dinner, which interrupted mealtime for the rest of the family. The psychologist found that in the morning, Jake would complete one or two steps of his routine before he became distracted and switched activities, despite his mother’s constant reminders. During dinnertime, Jake would leave his seat between 10 and 15 times over the course of the meal. Jake’s teachers were worried because Jake was only able to complete 50% of his homework. Further, his classmates would not pick Jake for team sports during recess because he often became distracted and wondered off during the game.

In this case, Jake’s symptoms would not be considered developmentally appropriate for a 10-year-old child. Further, his symptoms caused him to experience impairment at home and school. Unlike Michael, Jake probably would be diagnosed with ADHD.

Life Problems from ADHD

Children diagnosed with ADHD face considerably worse long-term outcomes than do those children who do not receive such a diagnosis. In one investigation, 135 adults who had been identified as having ADHD symptoms in the 1970s were contacted decades later and interviewed (Klein et al., 2012). Compared to a control sample of 136 participants who had never been diagnosed with ADHD, those who were diagnosed as children

  • had worse educational attainment (more likely to have dropped out of high school and less likely to have earned a bachelor’s degree);
  • had lower SES;
  • held less prestigious occupational positions;
  • were more likely to be unemployed;
  • made considerably less in salary;
  • scored worse on a measure of occupational functioning, indicating, for example, lower job satisfaction, poorer work relationships, and more firings;
  • scored worse on a measure of social functioning, indicating, for example, fewer friendships and less involvement in social activities;
  • were more likely to be divorced; and
  • were more likely to have non-alcohol-related substance abuse problems. (Klein et al., 2012)

Longitudinal studies also show that children diagnosed with ADHD are at higher risk for substance abuse problems. One study reported that childhood ADHD predicted later drinking problems, daily smoking, and use of marijuana and other illicit drugs (Molina & Pelham, 2003). The risk of substance abuse problems appears to be even greater for those with ADHD who also exhibit antisocial tendencies (Marshal & Molina, 2006).

Causes of ADHD

Family and twin studies indicate that genetics play a significant role in the development of ADHD. Burt (2009), in a review of 26 studies, reported that the median rate of concordance for identical twins was 0.66 (one study reported a rate of 0.90), whereas the median concordance rate for fraternal twins was 0.20. This study also found that the median concordance rate for unrelated (adoptive) siblings was 0.09; although this number is small, it is greater than zero, thus suggesting that the environment may have at least some influence. Another review of studies concluded that the heritability of inattention and hyperactivity were 71% and 73%, respectively (Nikolas & Burt, 2010).

Illustration of brain with prefrontal cortex highlighted in blue.

Figure 1. The left prefrontal cortex is often affected in ADHD.

The specific genes involved in ADHD are thought to include at least two that are important in the regulation of the neurotransmitter dopamine (Gizer, Ficks, & Waldman, 2009), suggesting that dopamine may be important in ADHD. Indeed, medications used in the treatment of ADHD, such as methylphenidate (Ritalin) and amphetamine with dextroamphetamine (Adderall), have stimulant qualities and elevate dopamine activity. People with ADHD show less dopamine activity in key regions of the brain, especially those associated with motivation and reward (Volkow et al., 2009), which provides support to the theory that dopamine deficits may be a vital factor in the development this disorder (Swanson et al., 2007).

Brain imaging studies have shown that children with ADHD exhibit abnormalities in their frontal lobes, an area in which dopamine is in abundance. Compared to children without ADHD, those with ADHD appear to have smaller frontal lobe volume, and they show less frontal lobe activation when performing mental tasks. Recall that one of the functions of the frontal lobes is to inhibit our behavior. Thus, abnormalities in this region may go a long way toward explaining the hyperactive, uncontrolled behavior of ADHD.

By the 1970s, many had become aware of the connection between nutritional factors and childhood behavior. At the time, much of the public believed that hyperactivity was caused by sugar and food additives, such as artificial coloring and flavoring. Undoubtedly, part of the appeal of this hypothesis was that it provided a simple explanation of (and treatment for) behavioral problems in children. A statistical review of 16 studies, however, concluded that sugar consumption has no effect at all on the behavioral and cognitive performance of children (Wolraich, Wilson, & White, 1995).

sour gummy worms

Figure 2. Although foods with high sugar content aren’t likely to be healthy and may contribute to temporary hyperactivity even in children without ADHD, no evidence supports the idea that the avoidance of sugar prevents or cures ADHD.

Additionally, although food additives have been shown to increase hyperactivity in non-ADHD children, the effect is rather small (McCann et al., 2007). Numerous studies, however, have shown a significant relationship between exposure to nicotine in cigarette smoke during the prenatal period and ADHD (Linnet et al., 2003). Maternal smoking during pregnancy is associated with the development of more severe symptoms of the disorder (Thakur et al., 2013).

Is ADHD caused by poor parenting? Not likely. Remember, the genetics studies discussed above suggested that the family environment does not seem to play much of a role in the development of this disorder; if it did, we would expect the concordance rates to be higher for fraternal twins and adoptive siblings than has been demonstrated. All things considered, the evidence seems to point to the conclusion that ADHD is triggered more by genetic and neurological factors and less by social or environmental ones.

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The management of ADHD typically involves psychotherapy or medications either alone or in combination. While treatment may improve long-term outcomes, it does not get rid of negative outcomes entirely. Medications used include stimulants and sometimes antidepressants. In those who have trouble focusing on long-term rewards, a large amount of positive reinforcement has shown to improve task performance. ADHD stimulants also improve persistence and task performance in children with ADHD.

The use of behavioral therapies in ADHD is the recommended first-line treatment in those who have mild symptoms or are preschool-aged (and often too young for medication). Psychological therapies used include the following: psychoeducational input, behavior therapy, CBT, interpersonal psychotherapy, family therapy, school-based interventions, social skills training, behavioral peer intervention, organization training, parent management training, and neurofeedback. Training in social skills, behavioral modification, and medication may have some limited beneficial effects. The most important factor in reducing later psychological problems, such as major depression, criminality, school failure, and substance use disorders, is the formation of friendships with people who are not involved in delinquent activities.

Kids playing soccer

Figure 3. Exercising while on stimulant medication augments the effect of the medication on executive function. It is believed that these short-term effects of exercise are mediated by an increased abundance of synaptic dopamine and norepinephrine in the brain.

Regular physical exercise, particularly aerobic exercise, is an effective add-on treatment for ADHD in children and adults, particularly when combined with stimulant medication, although the best intensity and type of aerobic exercise for improving symptoms are not currently known. In particular, the long-term effects of regular aerobic exercise in ADHD individuals include better behavior and motor abilities, improved executive functions (including attention, inhibitory control, and planning, among other cognitive domains), faster information processing speed, and better memory. Parent-teacher ratings of behavioral and socio-emotional outcomes in response to regular aerobic exercise include better overall function, reduced ADHD symptoms, better self-esteem, reduced levels of anxiety and depression, fewer somatic complaints, better academic and classroom behavior, and improved social behavior.

Stimulant medications are the pharmaceutical treatment of choice. Stimulants have at least some effect on symptoms: in the short term, in about 80% of people. Methylphenidate appears to improve symptoms as reported by teachers and parents. There is little evidence on the effects of medication on social behaviors and as of 2015, the long-term effects of ADHD medication have yet to be fully determined. MRI studies suggest that long-term treatment with amphetamine or methylphenidate decreases abnormalities in brain structure and function found in subjects with ADHD. A 2018 review found the greatest short-term benefit with methylphenidate in children and amphetamines in adults.

Dig Deeper: Why Is the Prevalence Rate of ADHD Increasing?

Many people believe that the rates of ADHD have increased in recent years, and there is evidence to support this contention. In a recent study, investigators found that the parent-reported prevalence of ADHD among children (four through 17 years old) in the United States increased by 22% during a four-year period, from 7.8% in 2003 to 9.5% in 2007 (CDC, 2010). Over time, this increase in parent-reported ADHD was observed in all sociodemographic groups and was reflected by substantial increases in 12 states (Indiana, North Carolina, and Colorado were the top three). The increases were greatest for older teens (ages 15–17), multiracial and Hispanic children, and children with a primary language other than English. Another investigation found that from 1998 to 2000 through 2007–2009 the parent-reported prevalence of ADHD increased among U.S. children between the ages of five to 17 years old, from 6.9% to 9.0% (Akinbami, Liu, Pastor, & Reuben, 2011).

A major weakness of both studies was that children were not actually given a formal diagnosis. Instead, parents were simply asked whether or not a doctor or other health-care provider had ever told them their child had ADHD; the reported prevalence rates thus may have been affected by the accuracy of parental memory. Nevertheless, the findings from these studies raise important questions concerning what appears to be a demonstrable rise in the prevalence of ADHD. Although the reasons underlying this apparent increase in the rates of ADHD over time are poorly understood and, at best, speculative, several explanations are viable: ADHD may be over-diagnosed by doctors who are too quick to medicate children as a behavior treatment. There is greater awareness of ADHD now than in the past. Nearly everyone has heard of ADHD, and most parents and teachers are aware of its key symptoms. Thus, parents may be quick to take their children to a doctor if they believe their child possesses these symptoms, or teachers may be more likely now than in the past to notice the symptoms and refer the child for evaluation. The use of computers, video games, iPhones, and other electronic devices has become pervasive among children in the early 21st century, and these devices could potentially shorten children’s attention spans. Thus, what might seem like inattention to some parents and teachers could simply reflect exposure to too much technology. ADHD diagnostic criteria have changed over time.

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Key Takeaways: ADHD


attention deficit/hyperactivity disorder (ADHD): childhood disorder characterized by inattentiveness and/or hyperactive, impulsive behavior