Diagnosis and Treatment of Attention Deficit Hyperactivity Disorder

Introduction

Attention deficit hyperactivity disorder (ADHD) is the most commonly diagnosed behavioral disorder of childhood, estimated to affect 3 to 5 percent of school-age children. Its core symptoms include developmentally inappropriate levels of attention, concentration, activity, distractibility, and impulsivity. Children with ADHD usually have functional impairment across multiple settings including home, school, and peer relationships. ADHD has also been shown to have long-term adverse effects on academic performance, vocational success, and social-emotional development.

Despite the progress in the assessment, diagnosis, and treatment of children and adults with ADHD, the disorder has remained controversial. The diverse and conflicting opinions about ADHD have resulted in confusion for families, care providers, educators, and policymakers. The controversy raises questions concerning the literal existence of the disorder, whether it can be reliably diagnosed, and, if treated, what interventions are the most effective.

One of the major controversies regarding ADHD concerns the use of psychostimulants to treat the condition. Psychostimulants, including amphetamine, methylphenidate, and pemoline, are by far the most widely researched and commonly prescribed treatments for ADHD. Because psychostimulants are more readily available and are being prescribed more frequently, concerns have intensified over their potential overuse and abuse.

This 2 1/2 day conference brought together national and international experts in the fields of relevant medical research and health care as well as representatives from the public.

After 1 1/2 days of presentations and audience discussion, an independent, non-Federal consensus panel chaired by Dr. David J. Kupfer, Thomas Detre Professor and Chair, Department of Psychiatry, University of Pittsburgh, weighed the scientific evidence and wrote a draft statement that was presented to the audience on the third day. The consensus statement addressed the following key questions:

• What is the scientific evidence to support ADHD as a disorder?
• What is the impact of ADHD on individuals, families, and society?
• What are the effective treatments for ADHD?
• What are the risks of the use of stimulant medication and other treatments?
• What are the existing diagnostic and treatment practices, and what are the barriers to appropriate identification, evaluation, and intervention?
• What are the directions for future research?

The primary sponsors of this conference were the National Institute on Drug Abuse, the National Institute of Mental Health, and the National Institutes of Health (NIH) Office of Medical Applications of Research. The conference was cosponsored by the National Institute of Environmental Health Sciences, the National Institute of Child Health and Human Development, the U.S. Food and Drug Administration, and the Office of Special Education Programs, U.S. Department of Education.

1. What Is the Scientific Evidence To Support ADHD as a Disorder?

The diagnosis of ADHD can be made reliably using well-tested diagnostic interview methods. However, as of yet, there is no independent valid test for ADHD. Although research has suggested a central nervous system basis for ADHD, further research is necessary to firmly establish ADHD as a brain disorder. This is not unique to ADHD, but applies as well to most psychiatric disorders, including disabling diseases such as schizophrenia. Evidence supporting the validity of ADHD includes the long-term developmental course of ADHD over time, cross-national studies revealing similar risk factors, familial aggregation of ADHD (which may be genetic or environmental), and heritability.

Additional efforts to validate the disorder are needed: careful description of the cases, use of specific diagnostic criteria, repeated followup studies, family studies (including twin and adoption studies), epidemiologic studies, and long-term treatment studies. To the maximum extent possible, such studies should include various controls, including normal subjects and those with other clinical disorders. Such studies may provide suggestions about subgrouping of patients that will turn out to be associated with different outcomes, responses to different treatment, and varying patterns of familial characteristics and illnesses.

Certain issues about the diagnosis of ADHD have been raised that indicate the need for further research to validate diagnostic methods.

1. Clinicians who diagnose this disorder have been criticized for merely taking a percentage of the normal population who have the most evidence of inattention and continuous activity and labeling them as having a disease. In fact, it is unclear whether the signs of ADHD represent a bimodal distribution in the population or one end of a continuum of characteristics. This is not unique to ADHD as other medical diagnoses, such as essential hypertension and hyperlipidemia, are continuous in the general population, yet the utility of diagnosis and treatment have been proven. Nevertheless, related problems of diagnosis include differentiating this entity from other behavioral problems and determining the appropriate boundary between the normal population and those with ADHD.
2. ADHD often does not present as an isolated disorder, and comorbidities (coexisting conditions) may complicate research studies, which may account for some of the inconsistencies in research findings.
3. Although the prevalence of ADHD in the United States has been estimated at about 3 to 5 percent, a wider range of prevalence has been reported across studies. The reported rate in some other countries is much lower. This indicates a need for a more thorough study of ADHD in different populations and better definition of the disorder.
4. All formal diagnostic criteria for ADHD were designed for diagnosing young children and have not been adjusted for older children and adults. Therefore, appropriate revision of these criteria to aid in the diagnosis of these individuals is encouraged.
5. In summary, there is validity in the diagnosis of ADHD as a disorder with broadly accepted symptoms and behavioral characteristics that define the disorder.