July 5, 2005 -- Bacteria often found in the throat or on the skin may trigger obsessive-compulsive disorder and other neurological conditions in some children.
Many people may carry the bacteria known to cause strep throat and have no symptoms of illness. Yet recent evidence has linked recent childhood infection with the bacteria to behavioral disorders.
Researchers compared children diagnosed with obsessive-compulsive disorder (OCD), Tourette's syndrome, or other tic conditions with children without these conditions. They found that children with one of the disorders were twice as likely to have had a strep infection within three months of diagnosis.
"This is one more bit of evidence suggesting that strep infections might trigger these behaviors in kids," researcher Robert L. Davis, MD, MPH, tells WebMD. "The findings definitely need to be replicated."
Do PANDAS Exist?
Roughly one in 50 adults are believed to suffer from OCD and between a third and one-half report that their obsessive thoughts and behaviors began during childhood.
Likewise, Tourette's syndrome, which is characterized by involuntary vocal and motor tics, is commonly diagnosed in childhood, sometimes as early as age 3.
OCD, Tourette's, and other tic disorders are related neuropsychiatric conditions. Over the last decade studies have linked their appearance in children to streptococcal infection.
The association is known by the acronym PANDAS, which stands for "pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection." But the link is still considered controversial by some in the field of childhood psychiatry.
In this study, published in the July issue of the journal Pediatrics, Davis and colleagues reviewed the medical records of 144 children diagnosed with OCD, Tourette's, or a separate tic disorder. They also reviewed the records of a larger group of children without the conditions.
They found that children with one of the neurological disorders were twice as likely to have had a strep infection in the three months before diagnosis. The association was even stronger for kids who had more than one strep infection.
Children who had multiple strep infections over the course of a year had a 13-fold increase in risk for Tourette's.
If strep infection does trigger the neurological disorders, or even cause them, the thinking is that antibodies produced during infection are to blame, researcher Lorene Mell, MD, tells WebMD. Antibodies are proteins the body produces to fight infection.
These conditions may be autoimmune in nature. Antibodies directed against certain regions of the brain and nerve fiber are found at higher rates in people with OCD and in children with tics and Tourette's syndrome.
Weighing the Evidence
Pediatric OCD specialist Henrietta Leonard, MD, tells WebMD that she is convinced that strep infections can trigger OCD and tic disorders in some children. She has done research on the phenomenon and says it is not uncommon for her to find unidentified strep infections in kids with newly diagnosed OCD and tic conditions.
"When you see this all the time clinically you know that it is not a coincidence," she says. "People say this is still controversial, but there is now a fairly large body of literature supporting this link."
Leonard says that a child being evaluated for OCD or tic disorders should be given a throat culture to test for strep infection and should be treated with antibiotics if they are infected. She says she has seen improvements in OCD and tic symptoms in some of her own patients treated with antibiotics.
But she adds that only a small percentage of kids with OCDs and tic disorders seem to have strep infections.
"The hard part is figuring out which subgroup of kids with OCD and tics are strep related and which are not," she says.
Although the data support the existence of PANDAS, a direct link between strep infection leading to the neurological disorder in children is yet unproven, write the researchers.
Additional research is needed and should include an assessment of the interaction between genetics, strep infection, and risk of PANDAS.