Strep infection sets off tics in some kids.

Some children develop motor or vocal tics, obsessions, compulsions, or combinations of these symptoms shortly after a streptococcal infection, such as strep throat. Researchers call such cases PANDAS, an acronym for pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections.

In the first study of its kind, scientists have found elevated rates of obsessive-compulsive disorder (OCD) and tic ailments, including Tourette's disorder, in the parents and siblings of children with PANDAS. These results support the theory that some families carry a genetic susceptibility to OCD and tic disorders that gets activated by childhood strep infection, according to a team led by social worker Lorraine Lougee and psychiatrist Susan E. Swedo, both of the National Institute of Mental Health (NIMH) in Bethesda, Md.

In this theory, which the researchers describe in the September JOURNAL OF THE AMERICAN ACADEMY OF CHILD AND ADOLESCENT PSYCHIATRY, as-yet-unspecified genes direct strep-induced antibodies to attack brain areas involved in movement and monitoring for potential danger.

"This is groundbreaking work that could lead to new insights into the causes of at least some cases of childhood OCD and tic disorders," remarks psychiatrist James F. Leckman of Yale University School of Medicine.

Prior investigations have linked strep infections to between 5 and 15 percent of childhood OCD and Tourette's disorder cases, Leckman notes.

About 2 percent of the people in the United States suffer from OCD at some time in their lives, although it's unclear how many cases begin in childhood. The condition revolves around obsessive thoughts that impel compulsive actions, such as checking door locks over and over for hours for fear of letting in a burglar. Tourette's disorder, marked by severe motor and vocal tics, afflicts 4 or 5 out of every 10,000 people.

The NIMH group recruited 42 boys and 12 girls, whose ages ranged from 6 to 12, who had developed OCD or tic disorders, or had experienced a dramatic worsening of those conditions, during the few weeks or months after a strep infection. Medical records, as well as biological tests for the presence of strep infection or elevated antistreptococcus antibodies, confirmed that PANDAS was the correct diagnosis in these cases.

In addition, Lougee and her coworkers conducted psychiatric interviews with 100 biological parents and 39 biological siblings of the children.

Fourteen kids with PANDAS had at least one immediate family member with OCD, the researchers report. A total of 15 parents and two siblings received an OCD diagnosis. Moreover, 21 children had at least one family member with a history of a motor or vocal tic.

Most affected parents told the scientists that their OCD symptoms or tics had begun in childhood or adolescence. One parent had Tourette's disorder and several others had severe tics that fell just short of that condition.

The new study finds that OCD and tic disorders run in the families of children with PANDAS to about the same extent as had been found in previous studies of people with OCD and tic disorders. However, those investigations didn't identify people whose ailments had a link to childhood strep infection.

The NIMH investigators are currently evaluating the safety and effectiveness of plasma exchange and immunoglobulin treatment for children with severe strep-triggered OCD and tics.

Physicians are aware that strep infections can cause heart problems in children, says psychiatrist Pierre Blier of the University of Florida School of Medicine in Gainesville. "We should be just as concerned about the possibility of psychiatric complications," he concludes.