New research suggests that strep infections in children may increase involuntary movements and disruptive behaviors associated with some psychiatric disorders.
In an eight-month study of 693 children in a Florida public school system, University of Florida researchers found that shortly after the number of strep infections in the group increased, there was a corresponding rise in involuntary movements and disruptive behaviors — symptoms that could indicate a neurological cause.
"During the fall months when there are more strep infections, after a short time lag, there are increased behavioral symptoms — enough to indicate an association," said Tanya Murphy, M.D., an associate professor of psychiatry in the College of Medicine. "We did not assess the children for particular neuropsychiatric disorders, so we're not saying actual disorders were present in the children, but the symptoms were there."
The research adds weight to the existence of PANDAS, short for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus. Some scientists think a host of problems such as tics, personality change, anxiety and obsessive-compulsive disorder may be triggered by strep infections in some children.
Scientists suspect group A streptococcal infections — the kind that cause strep throat in some people but occur without symptoms in others — may cause the body's immune system to interact with brain cells that cause psychiatric symptoms in a small percentage of young patients.
In findings published this month in the Journal of Biological Psychiatry, UF researchers describe how they found an association between strep infections and neuropsychiatric symptoms within a group of students in a Florida school system. Previously, research in the PANDAS field focused on children already diagnosed with psychiatric disorders.
"We were looking for patterns of association in just a standard group of children who ranged in age from 3 to 12 years," Murphy said. "We were seeing 693 kids once a month for eight months and made more than 5,000 observations."
Throat cultures were collected to test for group A streptococcal infections while a clinician screened for tics and other involuntary movements of the fingers, wrists, arms, elbows and shoulders.
In addition, as the children waited in line for their neurological screenings, the researcher made note of tic movements or any of nine categories of behaviors, ranging from fidgeting and hair-twirling to excessive touching and grimacing.
Analysis showed about 26 percent of children who had two or more strep infections displayed abnormal symptoms compared with 17 percent of children who were not infected or infected only once.
Strep throat and other group A strep infections are common in schools and environments where bacteria are easily spread. They are passed through direct contact with saliva or nasal discharge from an infected person, according to the National Institute of Allergy and Infectious Diseases.
Depending on the season - strep peaks in December and January - more than one in three children will be infected. Not all of the children will have sore throat symptoms, but they carry the bacteria and can infect others.
"The medical perspective has always been that the carrier states are fairly benign, but maybe they are not as benign as we thought," Murphy said. "That's not to suggest that these states are increasing children's risk for rheumatic fever or other problems that can develop after an infection, but maybe there is a milder spectrum of effects that shouldn't always be ignored."
The research was funded in part through the National Institute of Mental Health. Other scientists involved include Sue Swedo, M.D., chief of the National Institute of Mental Health's Pediatrics and Developmental Neuropsychiatry Branch, and Wayne Goodman, M.D., chairman of UF's psychiatry department.
Determining whether strep truly triggers psychiatric disorders in some children will require further exploration. Scientists would next like to monitor the effect of strep treatment on psychiatric symptoms or observe whether a patient's infection-fighting antibodies rise or fall in step with psychiatric symptoms.
"This is exactly the kind of study that was needed, a prospective evaluation to quantify the increased risk of neuropsychiatric or movement disorders following strep infections in the general pediatric population," said Loren Mell, M.D., of the University of Chicago. Mell was part of a team that published findings in 2005 that showed strep infections were associated with increased risk of obsessive-compulsive disorder, Tourette's syndrome or tic disorder in children who were already diagnosed with a psychiatric disorder.
"Further study to show prospectively that group A strep infections lead to neuropsychiatric disorders as determined by the Diagnostic and Statistical Manual of Mental Disorders criteria would help substantiate their findings," Mell said. "Interestingly their results are similar to ours in the sense that having multiple infections appears to confer a much higher risk of these disorders."