About three in every 1,000 children in the United States suffer from Tourette's syndrome, for a total of about 150,000 cases in the country, according to a survey published today by the Centers for Disease Control and Prevention. Previous estimates of its incidence had varied from one in 1,000 to 30 in 1,000. The new survey, published in the CDC's Morbidity and Mortality Weekly Report, is the first to provide hard numbers for the disorder. Most of the cases were classified by the children's parents as mild, but about one in four was considered moderate or severe.
Tourette's typically begins during childhood and symptoms become most severe between age 10 and 12. It is characterized most visibly by motor and vocal tics, which often cause victims to shout offensive words at inopportune times and without provocation. Those with the disorder also typically suffer from more subtle problems, including neurodevelopmental disorders, attention deficit/hyperactivity disorder, and obsessive-compulsive disorder. Having good data about the prevalence of the disorder is a first step toward understanding its links to these other problems, said Dr. Rebecca Bitsko of CDC, who led the new study.
The data were obtained from the recurring National Survey of Children's Health, in which 91,642 representative U.S. households were phoned and asked to provide information about their children's health. The most recent survey, conducted from April 2007 through July 2008, was the first to include questions about Tourette's.
The researchers found that Tourette's is three times as common in boys as in girls and about twice as common in adolescents between age 12 and 17 as in those age 6 to 12. It is also more than twice as common in Caucasians as in African Americans and Hispanics. It is not clear why such ethnic differences exist -- or even if, in fact, they do. Some experts think the perceived differences may simply be the result of differing access to healthcare and attitudes about the necessity for treatment of tics.
-- Thomas H. Maugh II