Obsessions and compulsions, as well as motor and vocal tics, have a strong genetic input, increasing evidence suggests. But how about obsessions and compulsions or tics that are triggered, or at least exacerbated, by a streptococcal infection?

They too appear to have a genetic input, a study conducted by a group of National Institute of Mental Health researchers and reported in the September Journal of the American Academy of Child and Adolescent Psychiatry suggests. This is believed to be the first study to report on the family history of such patients, they point out.

Lorraine Lougee, L.C.S.W., Susan Perlmutter, M.D., Rob Nicolson, M.D., Marjorie Garvey, M.D., and Susan Swedo, M.D.—all of the Pediatrics and Developmental Neuropsychiatry Branch of NIMH in Bethesda, Md.—zeroed in on 54 children whose obsessions and compulsions or tics had been linked to a strep infection. That is, these were children with PANDAS (pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection). In 48 of the youngsters (about 90 percent), symptom onset had coincided with throat cultures for strep infection. In the remaining six (about 10 percent) without a documented strep infection at onset, all had had at least one symptom exacerbation associated with a documented strep infection.

The researchers then determined whether 100 parents and 57 siblings of these children had ever had a tic disorder and whether 100 parents and 39 siblings of the youngsters had ever had obsessive-compulsive disorder, subclinical obsessive-compulsive disorder, obsessive-compulsive personality disorder, or another psychiatric condition—attention-deficit/hyperactivity disorder, generalized anxiety disorder, a major depressive episode, bipolar disorder, social phobia, a specific phobia, or panic disorder.

Thirty-nine percent of the youngsters were found to have a parent or sibling who had had tics at some point, and 26 percent had a parent or sibling who had experienced obsessive-compulsive disorder. When the data were examined by family status, 67 percent of the children had a family member who had at some point experienced obsessive-compulsive disorder, subclinical obsessive-compulsive disorder, obsessive-compulsive personality disorder, and/or a tic disorder.

These rates of tic disorders and obsessive-compulsive disorder in the first-degree relatives of children with strep-related obsessions and compulsions and tics are higher than those found in the general population. They are also similar to those reported for parents and siblings of persons with obsessions and compulsions or tics not related to strep. Thus genes seem to play a strong role in obsessions and compulsions and tics even when bacterial infection is involved, the investigators concluded.

Other interesting outcomes of the study were that 40 percent of the youngsters’ parents had experienced a major depression at some point and that 15 percent of the children’s parents had experienced generalized anxiety disorder at some time. These findings, the investigators noted, are not surprising since persons with obsessions and compulsions or tics also often experience anxiety and depression. But these findings, the investigators believe, also suggest that parents of young people diagnosed with strep-related obsessions and compulsions or tics may need psychiatric treatment themselves.

"Some parents who have undiagnosed depression, for example," the researchers write, "may become overwhelmed by their child’s illness and be unable to provide necessary support or to comply with a complex medical or behavioral therapeutic regimen until their own symptoms are treated."

In fact, the investigators stressed, "many of the parents who appear to have only depression or generalized anxiety may also have obsessive-compulsive disorder, and their undisclosed symptoms may have an additional impact on compliance."