This could mean that minority populations may have some protection against the condition, Scahill said. "But quite honestly, I sort of doubt that. The other explanation is that these children are less likely to come to treatment attention. It looks like we are missing more children in minority populations."
Dr. Robert King, medical director of the Tourette's Clinic at the Yale Child Study Center, said this is an important study that adds to the understanding of how widespread the condition is.
"As Tourette Syndrome was once, and sometimes still is, mistakenly believed to be inevitably a very rare, severe chronic disorder, these findings confirm an updated view of Tourette Syndrome as relatively common, usually mild, and likely to improve spontaneously by young adulthood," King said.
The prevalence may be even higher than the survey shows, since diagnosis was based on whether a health-care provider ever told the parent that the child had Tourette Syndrome, King said.
"Hence, the study may not have picked up on milder cases that had not been brought to clinical attention or those in populations with less access to clinicians knowledgeable about Tourette Syndrome and hence able or inclined to make the diagnosis," he said.
"The study also confirms the high rates of comorbidity with other disorders, such as ADHD, anxiety, learning problems, underlining the importance of diagnosis even if the tics themselves are not a source of distress or disability," he said.
For more information on Tourette Syndrome, visit the U.S. National Library of Medicine.
SOURCES: Lawrence D. Scahill, Ph.D., associate professor, nursing and child psychiatry, Yale University School of Medicine, New Haven, Conn.; Rebecca Bitsko, Ph.D., health scientist, U.S. Centers for Disease Control and Prevention, Atlanta; Robert King, M.D., medical director, Tourette's Clinic, Yale Child Study Center, and professor, child psychiatry, Yale University School of Medicine, New Haven, Conn.; June 5, 2009, Morbidity and Mortality Weekly Report