No Association Proven to Link Strep Throat and Neurologic Tics

A study published in Neurology found no correlation between increased tic activity after getting strep throat. 
    
“The link between streptococcus and tics in children is still a matter of intense debate,” said study author Davide Martino MD, PhD, of the University of Calgary in Alberta, Canada, and a member of the American Academy of Neurology. “We wanted to look at that question, as well as a possible link between strep and behavioral symptoms like obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD).”
  
Of the 715 participants, 308 experienced worsening symptoms but these were not correlated with strep exposure. Worsening symptoms of OCD also did not correlate with strep exposure.  However, when researchers looked at behavioral measures, they did find an association between strep exposure and an increase of about 20% in ADHD symptoms of hyperactivity and impulsiveness
  
The study involved 715 children and young adults with chronic tic disorders and 91% had a diagnosis of Tourette syndrome. Of the participants, 258 were diagnosed with ADHD and 227 with OCD. Participants were followed up an average of 16 months and evaluated during clinic visits every 4 months. During visits, throat swabs and blood samples were taken to check for infection with the strep bacteria. At the beginning of the study, 59 participants tested positive for strep bacteria and throughout the study 103 participants had a new exposure to strep bacteria. Changes in tic severity were monitored with diaries the parents kept, in-person visits, and telephone interviews.