No Link Found Between Streptococcus Infection and Development of Tics in Children

There is no association between Streptococcus infection and the development of tics in children with a parent or sibling who have a chronic tic disorder, such as Tourette syndrome, according to a study published in Neurology.

"There has been much debate about whether the bacteria that causes strep throat, group A streptococcus, plays a role in the development of tic disorders, with previous research providing mixed results," said study author Anette Eleonore Schrag, MD, PhD, of University College London in the United Kingdom, in a press release. "Our research looked at a population of children at a higher risk of developing tics due to having a first-degree relative with a tic disorder and did not find an association between exposure to strep and the development of tics."

The researchers evaluated 259 children, from 3 to 10 years of age, who have a parent or sibling diagnosed with a chronic tic disorder but do not have the disorder themselves. The children in the study were tested for strep throat infection at the start and during the study via throat swabs, blood tests, or a combination of these tests.

The children were tracked for an average of 1.6 years and alternated in person or telehealth medical evaluations every 2 months. Their parents maintained a weekly diary and reported any potential sign of tics in their child as soon as possible.

The onset of tics was defined as the appearance of a sudden, involuntary movement or vocalization on 3 or more days over a 3-week period, which was then confirmed on examination. Throughout the duration of the study, 61 children (24%) developed tics.

The study authors then compared the frequency of tic disorders among those who had a strep infection with children who did not, which showed no association, even after adjusting for age, sex, and parental education level.

During a follow-up analysis 2 years after the study ended, 7 more children developed tics; however, there was still no association found between tics and strep.

Independent of strep, the study showed a strong association between sex and the onset of tics, with girls showing a 60% lesser risk of developing tics than boys, which is similar to the findings of previous studies, according to the authors of the current study.

One limitation of the study was that the children were enrolled at multiple sites across Europe instead of a single site, which may have produced minor inconsistencies in the assessment of the participants, according to the authors.

“Future studies are needed to investigate whether pathogens other than strep, or other factors that affect the immune system, play a specific role in the development of tics,” Schrag said in a press release.

Reference

Anette Eleonore Schrag et al. Lack of Association of Group A Streptococcal Infections and Onset of Tics: European Multicenter Tics in Children Study. Neurology, 2022 DOI: 10.1212/WNL.0000000000013298