CDC Study Confirms ADHD/Learning Disability Link

About one-half of the 1.6 million elementary school-aged children diagnosed with attention-deficit/hyperactivity disorder (ADHD), a condition also known as attention-deficit disorder (ADD), have also been identified as having a learning disability (LD), according to a new study by the Centers for Disease Control and Prevention (CDC).

The report, Prevalence of Attention-Deficit Disorder and Learning Disability: United States, 1997-1998, is based on data from the CDC's National Health Interview Survey (NHIS), which focused on children ages 6 to 11. The NHIS was a national household survey that collected health status and sociodemographic information on the civilian noninstitutionalized population of the United States.

According to the report, from 1997-1998, more than 2.6 million children ages 6-11 were reported to have ever had a diagnosis of either ADD or LD. Three percent of the children had been diagnosed with only ADD, 4 percent with only LD, and 4 percent with both conditions, according to the NHIS.

The NHIS is the first national survey to include questions on the prevalence of both diagnosed ADD and LD in school-aged children. According to the study, the differences in the way in which ADD and LD were measured in other national and community-based studies makes it difficult to compare these estimates with the NHIS results.

"This report serves as a snapshot of a condition that has important consequences for the development of school-age children," said David Fleming, M.D., acting CDC director. "However, much more needs to be learned about ADHD and about the spectrum of impairments associated with ADHD."

The advocacy organization CHADD (Children and Adults with Attention-Deficit/Hyperactivity Disorder) applauded the CDC for highlighting the significance of ADHD and learning disabilities.

"This report reinforces what the leading scientific institutions have been telling us all along," said Clarke Ross, chief executive of CHADD. "Individuals affected by ADHD rarely have ADHD alone. Nearly 70 percent of those with ADHD simultaneously cope with other conditions such as learning disabilities, mood disorders, anxiety and more."

Ross said the complexity of the disorders combined with the challenge of appropriate treatment for individuals with ADHD points to the need for additional research, early intervention and appropriate assessment.

The report found that among children with the LD diagnosis, 54 percent were in special education. This was nearly five times greater than the percent observed for children with ADD and no LD and over 23 times the percent reported for children with neither ADD nor LD.

Among children with LD and no ADD, 46 percent attended special education, and among those with both ADD and LD, 65 percent were in special education. Among children with LD, the percent of boys and girls in special education was similar.

According to the report, the percent of boys with only ADD was almost three times greater than the percent of girls with ADD, and the percent of boys with both diagnoses was over two times greater than the percent of girls with both diagnoses. The percent of boys and girls with only LD was similar.

The findings also indicated that white non-Hispanic children were more often diagnosed with only ADD than black non-Hispanic or Hispanic children. However, the percent of children with only LD did not vary significantly by race or ethnicity.

The report found that in the last 30 years, behavioral and learning disorders in school-aged children have become major health concerns in the U.S. The study authors noted, however, that lack of health care insurance and limited access to mental health services have left some children undiagnosed and untreated.

"There has been concern in some circles that ADHD has been overdiagnosed among those with regular access to health care," said Fleming. "And there is equal concern that the problem may be underdiagnosed among those who have limited or no access to care. It's clearly important to accurately identify children with ADHD and ensure that they have appropriate health care."

Many adults have identified underachievement and failure in school as serious problems facing youth. At the same time, said the report, educators have reported a rise in the number of school-aged children with disabling behavioral and learning disorders.

The report found that health problems, including impaired vision and hearing, allergies, and chronic health conditions other than asthma, were reported more frequently for children with LD than for children with neither ADD nor LD.

The percent of children with four or more health care visits during the past 12 months was 34 percent for children with only LD, 45 percent for children with only ADD, and 51 percent for children with both diagnoses. Among children with neither ADD nor LD, 23 percent had four or more health care visits during the past 12 months.

Children with ADD more often had contact with a mental health professional, used prescription medication regularly, and had frequent health care visits, said the report.

The study noted that the regular use of prescription medication was highest among children with ADD: 54 percent for children with only ADD and 61 percent for children with both ADD and LD. Prescription medication use for children without ADD was lower: 14 percent for children with only LD and 6 percent for children with neither ADD nor LD.

The full report is available at www.cdc.gov.

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