ADHD is characterized by hyperactivity, impulsive behavior and an inability to pay attention to tasks; the condition affects social behaviors and achievement at school and work.

A new study says an estimated 8.7 percent of U.S. children age 8 to 15 meet the diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD). Less than half of that are being treated for it.

Is ADHD really on the rise or are the criteria too broad? It depends on who you ask because it doesn't follow any particular medical pattern. Boys have it more than girls and hispanics less than whites. The poorest one-fifth of children were more likely than the wealthiest one-fifth of children to have it.

A disorder that primarily impacts poor white American children?

“Reasons for the increased likelihood of ADHD in poorer children may include the elevated prevalence of ADHD risk factors (i.e., premature birth and in utero or childhood exposures to toxic substances) in this group,” the authors write. “In addition, given the high heritability of ADHD and its negative impact on social, academic and career outcomes, it is plausible that families with ADHD may cluster within the lower socioeconomic strata.”

Yes, ADHD families often move to be near each other, they wrote.

To conduct the study, Tanya E. Froehlich, M.D., of Cincinnati Children’s Hospital Medical Center, and colleagues studied a group of 3,082 children designed to represent the entire population of 8- to 15-year-olds in the United States. Between 2001 and 2004, children’s parents or other caregivers were interviewed by phone and provided information about each child’s ADHD symptoms, including when they first appeared and any impairment they caused during the previous year. They also reported whether their child had ever been diagnosed with ADHD or taken medicine to treat it, in addition to providing sociodemographic details.

Based on standard diagnostic criteria, 8.7 percent of the children (equivalent to 2.4 million children nationwide) fulfilled criteria for ADHD in the year prior to the survey. Hispanics were less likely than whites to have ADHD and boys were more likely than girls to meet criteria, although girls who did have ADHD were less likely to have their condition recognized. A total of 47.9 percent of the children who met ADHD criteria had previously been diagnosed with the condition.

Among children meeting criteria for ADHD, 39 percent had received some medication treatment and 32 percent were treated consistently with ADHD medications during the previous year. Despite the prevalence of ADHD in poorer children, they were least likely to receive medications consistently. This finding “warrants further investigation and possible intervention to ensure that all children with ADHD have equitable access to treatment when appropriate,” the authors conclude.

Overdiagnosed or a modern epidemic? It's hard to say but there aren't many disorders that impact a gender, a race, a nation and an economic class specifically so some skepticism is warranted.

Article: "Improving Attention-Deficit/Hyperactivity Disorder Treatment Outcomes Through Use of a Collaborative Consultation Treatment Service by Community-Based Pediatricians: A Cluster Randomized Trial", Jeffery N. Epstein; David Rabiner; Diane E. Johnson; David P. FitzGerald; Allan Chrisman; Alaattin Erkanli; Kevin K. Sullivan; John S. March; Peter Margolis; Edward C. Norton; C. Keith Conners, Arch Pediatr Adolesc Med. 2007;161:835-840.