Attention-deficit/hyperactivity disorder (ADHD) and learning disability (LD) are two of the most prevalent disorders occurring in children aged 6 to 17 years. In 2006, the National Centers for Health Statistics (NCHS) estimated that 4.5 million and 4.6 million children, respectively, have been diagnosed with ADHD or LD. Prescriptions for ADHD medications have increased dramatically in the past decade, with utilization in many states more than quadrupling, but the reason for the increase is not clear. The reason for the recent decline in the use of drugs that contain methylphenidate also is not known. The annual societal cost of illness for ADHD has been estimated to be between $36 and $52 billion (in 2005 dollars). Studies have demonstrated increases in substance abuse, risk-taking, and criminal behaviors among adolescents who have ADHD and other related disorders.
According to the NCHS, nearly 5% of children had ADHD without LD, 5% of children had LD without ADHD, and 4% of children had both disorders. The percentage of children aged 6 to 17 years who had ADHD increased at an annual rate of 3% from 1997 through 2006, but the percentage of children with LD did not change significantly. No significant change was found in the percentage of children aged 6 to 11 years who had ADHD; however, an annual increase of 4% occurred among those aged 12 to 17 years.
An increase in the percentage of children with ADHD occurred among both boys (2%) and girls (4%). The causes and risk factors contributing to ADHD are unknown, although the disorder appears to be more prevalent among boys.
Children whose birthweight was low (14.1%) were more likely than children who did not have a low birthweight (8.1%) to have LD. Among low-birthweight children, 7.5% and 7.9% of boys were more likely to have ADHD and LD, respectively, in comparison with girls (3% and 7.4%, respectively).
Hispanic children (5.3%) were less likely than non-Hispanic black children (8.6%) and non-Hispanic white children (9.8%) to have ADHD. No significant racial or ethnic differences were found in the percentage of children having LD without ADHD.
Children with ADHD (46.2%) were more likely than children without ADHD (4%) to have contact with a mental-health professional, utilize more prescription medications (62.7% vs. 10.6%), and make frequent health care visits (56.7% vs. 21.7%). Children with LD were more likely (59.3%) than children without this disorder (2.4%) to utilize special-education services.
The prevalence of mental retardation (6.5%), hearing or vision problems (4.5%), and allergies (36.8%) was lowest among children who had ADHD without LD; children who had LD without ADHD had the highest prevalence of mental retardation (36.6%). Children who had both ADHD and LD had the highest prevalence of hearing or vision problems (9.6%) and allergies (42.8%). The prevalence of asthma was lowest (20.8%) among children having LD without ADHD, and it was highest (22.2%) among children who had both.
Children with Medicaid coverage (5.9%) were more likely than uninsured (2.6%) and privately insured children (3.1%) to have ADHD, LD, or both disorders. These children also were more likely to utilize health care and special-education services.
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