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Risk for mental disorders higher after strep throat infection

Risk for any mental disorder, OCD and tic disorders was higher among individuals aged 18 years or younger with streptococcal or nonstreptococcal throat infection, particularly for those with strep throat.

“In recent years, an increasing body of evidence has pointed toward a critical role of the immune system and infections in the development of mental disorders. Childhood obsessive-compulsive disorder (OCD) and tic disorders have been suggested to be associated with infections caused by group A -hemolytic streptococcus, a hypothesis termed pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS), which are suggested to be caused by molecular mimicry in which antibodies directed toward the streptococcal bacteria cross-react with the basal ganglia of the brain, possibly owing to structural similarities between the streptococcal cell surface and proteins of the basal ganglia,” Sonja Orlovska, MD, of the University of Copenhagen, Denmark, and colleagues wrote.

To assess risk for mental disorders, particularly OCD and tic disorders, after streptococcal throat infection, researchers conducted a population-based cohort study of nationwide Danish register data for 1,067,743 children; of whom 349,982 tested positive for strep throat at least once. Analysis included 17 years of follow-up.

Participants with positive strep throat test results had increased risk for any mental disorder (IRR = 1.18; 95% CI, 1.15-1.21; P < .001), particularly OCD (IRR = 1.51; 95% CI, 1.28-1.77; P < .001) and tic disorders (IRR = 1.35; 95% CI, 1.21-1.5; P < .001), compared with those without a positive strep result.

Risk for any mental disorder and OCD was higher after a strep throat infection than after a nonstreptococcal infection, according to researchers.

However, participants with a nonstreptococcal throat infection also had increased risk for any mental disorder (IRR = 1.08; 95% CI, 1.06-1.11; P < .001), OCD (IRR = 1.28; 95% CI, 1.07-1.53; P = .006), and tic disorders (IRR = 1.25; 95% CI, 1.12-1.41; P < .001).

“We found that both individuals with a streptococcal throat infection and individuals with a nonstreptococcal throat infection had an increased risk of any mental disorder, OCD, and tic disorders; however, the risk of all mental disorders and of OCD was greatest in individuals with streptococcal throat infections,” the researchers wrote. “Our results could favor essential elements of the wider diagnostic concept of pediatric acute-onset neuropsychiatric syndrome.” – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.