THURSDAY, Feb. 11, 2021 (HealthDay News) -- For children with chronic tic disorders (CTD), group A Streptococcus (GAS) exposure seems not to be a contributing factor for tic exacerbations, according to a study published online Feb. 10 in Neurology.
Davide Martino, M.D., Ph.D., from the Cumming School of Medicine & Hotchkiss Brain Institute at the University of Calgary in Alberta, Canada, and colleagues followed 715 children with CTD for 16 months on average. During four-monthly study visits and telephone interviews, tic, obsessive-compulsive symptom, and attention-deficit/hyperactivity severity was assessed. Using four possible combinations of measures based on pharyngeal swab and serological testing, GAS exposures were analyzed.
The researchers identified 405 exacerbations in 308 participants (43 percent). Depending on GAS exposure definition, the proportion of exacerbations temporally associated with GAS exposure ranged from 5.5 to 12.9 percent. No significant association was detected for any of the four GAS exposure definitions with tic exacerbations (odds ratios, 1.006 to 1.235). There was an association noted for GAS exposures with longitudinal changes of hyperactivity-impulsivity symptom severity, varying from 17 to 21 percent depending on the definition of GAS exposure.
"While our findings suggest that strep is not likely to be one of the main triggers for making tics worse, more research is needed into other possible explanations," Martino said in a statement. "For example, the social stress of having this disorder could be implicated in making tics worse more than infections. It's also possible another pathogen might be triggering an immune response associated with tic worsening."
Several authors disclosed ties to the biopharmaceutical industries.