Attention deficit hyperactivity disorder: overview and clinical considerations

ADHD

The Growing Incidence of ADHD

Attention Deficit Hyperactivity Disorder (ADHD), a neurological condition characterized by inattention, restlessness and impulsivity, is commonly diagnosed in early childhood and affects between 3 and 5% of American children, according to the National Institute of Mental Health. "In a classroom of 25 to 30 children, it is likely that at least one of them will have ADHD" (Ramer, p. 4). Studies that have been done in the area of ADHD, and many school teachers, say these numbers are conservative estimates. There is a growing belief that ADHD is growing in incidence. The thesis of this paper is that Attention deficit disorder and Hyperactivity disorder (ADHD) has increased in incidence during a ten-year span for school-aged children.

Public perception often says that the incidence of ADHD is increasing. But it is unclear whether this is the case. Research about the incidence of ADHD among children has been inconclusive, with studies suggesting a range of incidence from 1% to 18%. This is because there is no standardized research protocol for reporting ADHD. Therefore, it is difficult to determine whether the incidence is increasing (Barkley, 2006).

If ADHD becomes evident during the preschool or elementary years and the median age of onset is seven years, the disorder may still be diagnosed later on and the child has had it for several years by that time (Kessler, p. 617). According to the 2001 figures from the American Society of Pediatrics, 12% percent of youth in America suffer from the disorder. It is the most commonly diagnosed behavioral disorder among children, but misunderstanding of its symptoms and etiology has created confusion and controversy. Misunderstanding of the disorder has led to undertreatment in children (Dopheide, p. 1).

Current Status of ADHD in the United States

In November of 1998, the National Institutes of Health (NIH) invited 44 experts from across the United States in psychiatry, psychology, epidemiology, biostatistics, and pediatrics to develop a consensus statement addressing key diagnostic and treatment issues on ADHD (NIH, p. 1). The resulting statement confirmed that ADHD is a valid disorder with measurable and significant impairment in functioning caused by inattention, impulsivity, and hyperactivity. These experts reported that there is a 3% to 5% incidence in school age children and spoke to a need for improved diagnosis, treatment, and follow-up. The need for better cooperation between parents, teachers, and healthcare providers to effect optimal assessment and treatment was strongly encouraged. The most effective treatment in relieving symptoms according to research, were stimulants, though the threshold of symptoms most appropriate for stimulant therapy had no consensus among the experts (NIH, p. 5).

Although rates for the incidence of ADHD are 5 to 10 times greater in the United States, compared to other countries, across the United States, there is regional variability in significant numbers for the diagnosis and treatment of ADHD. For example, in 1 Virginia school system 8% to 10% of 30,000 children in second to fifth grade were diagnosed with ADHD, whereas a lower 3% to 5% overall incidence was reported by the NIH. In the same study cultural differences in prescribing stimulants were reported. By fifth grade, 18% to 20% of white boys were prescribed methylphenidate, whereas rates for other ethnicities were significantly lower (LeFever, 1359).

There has also been found to be a regional variability of significant proportion across the United States in the incidence of ADHD and drug therapy prescribing. But there has been a general increase in both over the past 10 years. One epidemiologic study tracked 220,000 very young children through Medicaid and HMO databases from 1991-1995 and found 1.2% of these preschoolers were prescribed stimulants, 1.1% were prescribed antidepressants, and 0.32% were prescribed clonidine for behavioral control.

One way of tracking the prevalence of ADHD is through prescription of the drugs used for treatment of ADHD. This study shows a three-fold increase in stimulant prescribing, a two-fold increase in antidepressant prescribing, and a 28-fold increase in clonidine prescribing between 1991 and 1995. A greater acceptance of pharmacologic treatments for behavioral disorders in children was sited as a major reason for the increased prescribing for ages 2- to19-year-olds (Zito, p. 1026).

A well-documented public health issue is underdiagnosis and suboptimal treatment of children with ADHD. One study found that only 50% of children with identified ADHD in practice settings actually receive the care that the guidelines of the American Academy of Child and Adolescent Psychiatry call for. A lack of pediatric specialists, insurance obstacles, and long waiting lists are barriers to providing appropriate services.

In only seven years (between 1989 and 1996), services such as health counseling for children with ADHD increased 10-fold, and diagnostic services increased 3-fold. Psychotherapy provision, however, decreased from 40% to 25% during the same time. Follow-ups also decreased from 90% to only 75%. Other appropriate diagnosis and treatment barriers included a fear of stigma, unknown long-term effects of treatment, and fear of substance abuse (Hoagwood, p. 198).

Jeanette Ramer, associate professor of pediatrics at the Penn State College of Medicine, believes there has been an increase in ADHD. It is still uncertain whether the rise in number is due to having more children born with the condition or whether it is due to increased recognition and more frequent diagnosis. Ramer believes it is both. She believes the disorder is genetic. "About half the time when we diagnose a child, a parent will also have it" (Ramer, para. 2).

The brains of children with ADHD perform abnormally in two ways, indirectly observable by functional magnetic resonance imaging (fMRI). Primarily, their frontal lobes appear to have problems with regulation of dopamine, a type of brain chemical known as a neurotransmitter which is essential to smooth signaling between neurons and other cells. They may also show an imbalance of norepinephrine, another neurotransmitter that may regulate mood in addition to attention. We don't have direct measurements of these imbalances, but currently people are medicating on this principle, and it seems to be working (Ramer, 2006, para. 6).

Even more confusing than the biological components in determining who and how many have the disorder, are the sociological factors. The number of ADHD cases varies largely from region to region in America, suggesting that cultural norms may influence diagnosis. "We're not seeing a true picture of the incidence." Ramer notes that in central Pennsylvania, ADHD is "well-identified," but in other areas in the United States, as it is in most of Europe, the disorder is commonly dismissed as "only a behavioral problem," without taking the contributing neurological factors into consideration. To further confuse the picture, sociological conditions may bring the disorder to light, whereas in other places it might have remained hidden. "Chaotic households and a lack of a support system" can bring on ADHD symptom, as can demands at school. Children who are required to stay seated and complete ever-larger workloads "don't have the same opportunities to compensate that they may have had in years past." It may be no wonder that the onset of ADHD is typically noted during the first years of school (Ramer, 2006, para. 7).

Ramer is careful to distinguish childhood ADHD from a growing trend of adults being diagnosed with the disorder. The latter, she says, may be a fad. "It shouldn't appear de novo," which is to say that ADHD doesn't just pop up in adults who didn't suffer with it as children. In these cases, she suspects, what's being labeled ADHD is the result of a society that does not allow one to take time to relax and think about nothing, or it might mean job-related stress. "If you're asked to multi-task all the time, it promotes behaviors that can look similar to ADHD" (Ramer, 2006, para. 8).

Requiring the patient's parents to complete questionnaires that evaluate characteristics of ADHD, so they can recall what their son or daughter was like at the age of ten is one way to accurately diagnose an adult with the disorder. For those who doubt the biological basis of true ADHD in children, however, she asks: "If it were all behavioral, why would a child choose to be fidgety?" (Ramer, 2006, para. 11).

A diagnosis of ADHD is found not only by the presence of particular symptoms and behaviors in a child, but through concerns by parents or teachers about the child's behavior and whether the child has access to a doctor who can make the diagnosis. The NHIS depends on parents' reports of a child being diagnosed with ADHD. This means that whether the percentage of children with ADHD has increased in recent years is difficult to obtain as a certainty. Although the records show that recently more children have been diagnosed with and treated for ADHD, this reported increase may not reflect an actual increase in incidence, but it may show greater awareness of the condition, media attention, development of effective treatments, or other such factors. Continued tracking of ADHD in coming years should be useful for evaluating trends in the diagnosis of ADHD (Attention, 2006).

It is easier to focus on ADHD statistics for children of school age (5-17 years old), because diagnosing ADHD in preschool aged children is difficult. Data from the NHIS indicate that:

In 2001-2004, 7.7% of children ages 5-17 were reported to have been diagnosed with attention deficit hyperactivity disorder (ADHD).

Nine percent of White non-Hispanic children, 8% of Black non-Hispanic children, 2% of Asian non-Hispanic children, and 4% of Hispanic children were reported to have ADHD.

Almost 13% of White non-Hispanic children living in families with incomes below poverty level were reported to have ADHD -- the highest of any group.

Two to three times more boys than girls are diagnosed with ADHD (Pastor, p. 206).

Well-known researcher, Dr. Russell Barkley, has detailed the differences that can occur in reporting, due to the type of criteria used in any given report. Reported variations in the prevalence of ADHD may be due to differences in the ways samples are chosen, the criteria is used to define ADHD, and the age range and gender composition used during the sampling. For example, lower rates of ADHD are reported when the full DSM-IV criteria and parent reports are used and higher rates when teacher-only reports are used (Barkley, 2004)

One of the more reliable studies was conducted in 2005 by the U.S. Center for Disease Control (CDC). This survey looked at the number of children reported by their parents in 2003 to have or ever have been diagnosed with AD/HD. The CDC found that:

The prevalence of AD/HD was about 7.8% nationally but varied quite a bit across socio-economic groups and geographic location. The lowest incidence of 5% was reported in Colorado and the highest, of 11% was reported in Alabama. California, at 5.34% had one of the lowest reported incidences. This same report indicates that only about half of children of ages 4-17 years who were diagnosed with ADHD actually took medication for AD/HD. The highest prevalence for medication treatment was for children aged 9 to 12 years (CDC, p. 842).

Interestingly enough the prevalence of reported AD/HD symptoms increased with age, becoming highest for males aged 16 years and females aged 11 years and was lowest for preschool children. The highest rates were also noted among English-speaking, non-Hispanic, and insured children. In addition, the rates were most prevalent in families in which the most highly educated adult had a high school diploma and lower in those families in which the most educated adult had more or less education than a high school diploma. Families with incomes below the poverty line were also more likely to report a child with AD/HD (CDC, p. 844).