PULLMAN, Wash. — The number of children visiting U.S. physicians for the treatment of attention deficit hyperactivity disorder tripled between 1990 and 1998, according to an article by Washington State University researchers published in the February issue of CNS Drugs.

While the number of office visits among boys diagnosed with ADHD still far exceeds that of the girls, the magnitude of increase was greater among girls, according to the article, “Is Attention Deficit Hyperactivity Disorder Increasing Among Girls in the U.S.?: Trends in Diagnosis and the Prescribing of Stimulants.”

Linda M. Robison, a researcher in the WSU College of Pharmacy, and her colleagues reported in the article that the number of physician office visits resulting in a diagnosis of ADHD increased from 947,208 in 1990 to 3,234,180 in 1998. Girls accounted for 15.7 percent of the office visits in 1990 – that number increased to 30.3 percent in 1998. The rate of physician visits per 1,000 U.S. girls resulting in a diagnosis of ADHD increased 2.7-fold, from 12.3 per 1,000 to 33.4 per 1,000. The rate among boys doubled.

The researchers also found that the prescribing of stimulant medications such as Ritalinâ for the treatment of ADHD nearly quadrupled among children 5-18 years old. The prescribing of a stimulant medication for the treatment of ADHD increased from 7.5 per 1,000 U.S. girls, to 21.1, a 2.8-fold increase. The rate among boys increased 2.2-fold.

The authors suggest the increases in both a diagnosis of ADHD and the prescribing of stimulants among children might be because of the rapidly increasing rate of diagnosis among girls, greater physician and public awareness of this condition, and the persistence of ADHD into adulthood.

Robison and her colleagues drew data for their analysis from the National Ambulatory Medical Care Survey.

Other researchers participating in the study include Tracy L. Skaer, David A. Sclar and Richard S. Galin. All are with the Pharmacoeconomics and Pharmacoepidemiology Research Unit in the WSU College of Pharmacy. Skaer is the WSU College of Pharmacy assistant dean. Sclar is Boeing Distinguished Professor at WSU, and a member of the research faculty at the Washington Institute for Mental Illness Research and Training. Galin is affiliated with the University of California at Los Angeles Neuro-Psychiatric Institute.