Question:

Why is Attention Deficit Disorder see so much more frequently in the United States than in other countries? Is the incidence increasing or is it just being diagnosed more?

Fifth grade teacher

Answer:

Many educators and parents have wondered if the incidence of AD/HD is increasing. Our perception often suggests that this is the case. However, research about the incidence of AD/HD among children has been inconclusive, with studies suggesting a range of incidence from 1% to 18%. This is because there is not a standardized research protocol for reporting the incidence of AD/HD. Thus, determining whether the incidence is increasing is difficult.

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. Variations in the prevalence of AD/HD can occur due to differences in the ways in which samples are chosen, the criteria used to define AD/HD, and the age range and gender composition of the sample. For example, lower rates of AD/HD are reported when the full DSM-IV criteria and parent reports are used and higher rates are reported when teacher only reports are used. The DSM-IV or Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, published by the American Psychiatric Association, is the book used by mental health professionals to diagnose mental health disorders.

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 incidence. This same report indicates that only about half of those children ages 4-17 years diagnosed with AD/HD actually took medication for AD/HD. The highest prevalence for medication treatment was in children aged 9 to 12 years.

In contrast, the incidence of adults taking medication for AD/HD has been increasing. A 2005 study by Medco Health Solutions found that the number of adults taking prescription drugs for AD/HD more than doubled from the years 2000 to 2004. One of the reasons for this increase may be than many people who began taking medication for AD/HD as children are now young adults. Even with the increase, only about 1% of the adult population takes medication to treat AD/HD.

Prevalence of reported AD/HD symptoms increased with age and was highest for males aged 16 years and females aged 11 years and lowest for preschool children. The highest rates were 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.

Studies of the incidence of AD/HD worldwide present a similar conundrum. The design of the studies are not the same, therefore, the results are not reliably comparable. However, the most reliable authorities describe a similar incidence world-wide. For example:

• 3.8% among Dutch children, by parent report
• 5.3% among Chinese children ages 6-11 years, using teacher ratings
• 14.9% among primary school children in the United Arab Emirates, using teacher ratings
• 19.8% among Ukranian children based on parent ratings of DSM-IV symptoms

Hope this helps to provide some perspective for you on the mystery of AD/HD.

Resources:

Centers for Disease Control and Prevention (2005) Prevalence of Diagnosis and Midication Treatment for Attention-Deficit/ Hyperactivity Disorder – United States, 2003. Morbidity and Mortality Weekly Report. September 2, 2005; vol.54, No. 34: pp. 842-847.

Barkley, Russell (2004) Attention-Deficit. Hyperactivity Disorder: Nature, Course, Outcomes, and Comorbidity. American Psychological Association

Barkley, Russell (2006) Attention Deficit Hyperactivity Disorder: A Handbook for Diagnosis and Treatment, Third Edition. New York, New York: Guilford Press

Hitti, M and Smith, M. ADHD Drups: Adult Use Doubled in 4 Years. MedicineNet.com. http://www.medicinenet.com/script/main/hp.asp

National Resource Center on AD/HD. http://www.help4adhd.org/en/about/statistics

St. Sauver,J. Mayo Clinic Proceedings, September 2004; vol 79: pp 1124-1131