Exposure to Group A streptococcus (GAS) does not appear to worsen symptoms of Tourette syndrome and other chronic tic disorders (CTDs) in children and adolescents, new research suggests.
Investigators studied over 700 children and teenagers with CTDs, one-third of whom also had attention deficit hyperactivity disorder and one-third who had obsessive-compulsive disorder (OCD).
The youngsters were followed for an average of 16 months and evaluated at 4-month intervals to see if they were infected with GAS. Tic severity was monitored through telephone interviews, in-person visits, and parental reports.
A little less than half the children experienced worsening of tics during the study period, but the researchers found no association between these exacerbations and GAS exposure.
There was also no link between GAS and worsening OCD. However, researchers did find an association between GAS exposure and an increase in hyperactivity and impulsivity in patients with ADHD.
“This study does not support GAS exposures as contributing factors for tic exacerbations in children with CTD,” the authors note.
“Specific work-up or active management of GAS infections is unlikely to help modifying the course of tics in CTD and is therefore not recommended,” they conclude.
The study was published online in Neurology.
‘Intense debate’
The association between GAS and CTD stems from the description of Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection (PANDAS) – a condition that is now incorporated in the pediatric acute neuropsychiatric syndromes (PANS), the authors note. Tics constitute an “accompanying feature” of this condition.
However, neither population-based nor longitudinal clinical studies “could definitely establish if tic exacerbations in CTD are associated with GAS infections,” they note.
“The link between streptococcus and tics in children is still a matter of intense debate,” said study author Davide Martino, MD, PhD, director of the Movement Disorders Program at the University of Calgary (Alta.), in a press release.
“We wanted to look at that question, as well as a possible link between strep and behavioral symptoms like obsessive-compulsive disorder and attention deficit hyperactivity disorder,” he said.
The researchers followed 715 children with CTD (mean age 10.7 years, 76.8% male) who were drawn from 16 specialist clinics in nine countries. Almost all (90.8%) had a diagnosis of Tourette syndrome (TS); 31.7% had OCD, and 36.1% had ADHD.
Participants received a throat swab at baseline, and of these, 8.4% tested positive for GAS.
Participants were evaluated over a 16- to 18-month period, consisting of:
- Face-to-face interviews and collection of throat swabs and serum at 4-month intervals.
- Telephone interviews at 4-month intervals, which took place at 2 months between study visit.
- Weekly diaries: Parents were asked to indicate any worsening of tics and focus on detecting the earliest possible tic exacerbation.
Beyond the regularly scheduled visits, parents were instructed to report, by phone or email, any noticeable increase in tic severity and then attend an in-person visit.
Tic exacerbations were defined as an increase of greater than or equal to 6 points on the Yale Global Tic Severity Scale-Total Tic Severity Score (YGTSS-TTS), compared with the previous assessment.
OCD and ADHD symptoms were assessed according to the Yale-Brown Obsessive-Compulsive Scale and the parent-reported Swanson, Nolan, and Pelham-IV (SNAP-IV) questionnaire.
The researchers divided GAS exposures into four categories: new definite exposure; new possible exposure; ongoing definite exposure; and ongoing possible exposure.