In the last few years, debate has heated up among both parents and doctors about a purported link between an infection caused by strep bacteria and the development of neuropsychiatric symptoms such as tics or obsessive-compulsive behavior. It's known as the PANDAS hypothesis – Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infection (PANDAS). Some doctors suspect that a strep infection triggers the body to produce antibodies that then attack or damage the brain, triggering or worsening tics or obsessive-compulsive disorder (OCD) and similar conditions in children.
"Doctors and parents are confused – they're not sure what to think. That's understandable. At this point, there's not enough data to resolve the issue," says neurologist Roger Kurlan, M.D., chief of the Cognitive and Behavioral Neurology Unit at the University of Rochester's Strong Memorial Hospital.
In the Pediatrics paper, Kurlan and Edward L. Kaplan, M.D., of the University of Minnesota assert that the criteria for establishing a connection between strep and behavioral disorders are too vague. For instance, one PANDAS hallmark is the abrupt onset of symptoms – but oftentimes once parents learn more about tics, they realize that their children have had them for quite awhile. The researchers say that while strep has been linked to other disorders such as rheumatic fever and Sydenham's chorea, large and carefully controlled studies have demonstrated those connections. They say the same is not true of PANDAS.
"Tics are such that they wax and wane," says Kurlan. "Oftentimes patients come in to the doctor's office soon after their symptoms have peaked, so it proves nothing to show that a child's symptoms subsided after they saw a doctor and were treated with antibiotics. It's quite possible that doctors could give such children a green-bean diet, and the children would get better. That's why we need a carefully done placebo-controlled study."
Perhaps once a month Kurlan treats a child whose parents are concerned about a possible link between the child's symptoms and strep, and he fields frequent phone calls from parents with similar concerns. And it's true, he says, that nearly every child he sees has had a strep infection, and that many had a recent infection. That's because it's extremely rare to find a child who has never been infected by strep, and most have been infected several times, Kurlan says. That means that nearly every child who has behavioral problems, or for that matter any problems, has been infected by strep. It's a little bit similar to arguing that drinking water causes broken bones, since nearly everyone who has broken a bone has drunk water or a water-based fluid the same day the fracture occurred.
"It's human nature to try to ascribe the onset of symptoms to a specific preceding event," he says. "There has to be a very carefully done clinical study to determine whether that preceding event is truly linked, or whether the two events occurred simultaneously just by chance. This is especially true when dealing with a very common event like strep infection.
"It's human nature to want a explanation. For almost every parent who recognizes tics and obsessive-compulsive behavior in their children, almost immediately, as soon as they recognize it, their minds shift into high gear, questioning why the child has these symptoms."
Kurlan says that about one in every five children has some tics at some point while growing up, and another one in five will show some obsessive-compulsive behavior. Most of these will outgrow the symptoms naturally within a few weeks or months, while generally children whose symptoms last more than a year may need treatment. He says that family history –genetics – appears to be the biggest cause of tics and OCD.
With funding from the National Institute of Neurological Disorders and Stroke, Kurlan is now studying 80 children who have physical or vocal tics or have been diagnosed with obsessive-compulsive disorder. A team from 11 medical centers around the country is tracking the youngsters for two years, logging both strep infections and behavioral difficulties in an attempt to uncover any link between the two. Every three months the children receive a physical exam, including a blood test, regardless of how they feel, since children with strep often feel fine. In addition, nurses obtain throat cultures from the children every month, and whenever children have a sore throat, or when their obsessive-compulsive symptoms or tics worsen, doctors examine them. The study will be completed next year.
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