Often, a child with TS has a parent or other close relative with TS. If one identical twin has TS, the other one almost always does.
Advances in genetics research have helped doctors identify gene mutations that cause many inherited conditions. Because brain chemicals, called neurotransmitters, might cause TS symptoms, researchers have examined genes related to neurotransmitters, especially dopamine. So far, no such genes have been proven to cause or worsen TS.
TS symptoms seem to wax and wane over time, for unclear reasons. Sometimes symptoms begin or worsen very suddenly. In addition, although TS runs in some families, the severity of symptoms can vary widely, even among identical twins. Taken together, these suggest that something in the environment may in some way affect TS symptoms.
For the past few years, research has increasingly focused on infections as a possible trigger of TS. When a virus or bacteria infects us, the white cells in our blood produce proteins, called antibodies, to fight the infection. Sometimes, a molecule on the surface of a bacteria or virus may have a very similar structure to molecules in our own bodies. When this happens, our immune system, while fighting off the infection, may also start to "cross-react" to parts of our own bodies, causing problems.
When a part of the human body comes under attack from its own immune system, this is called an "auto-immune" disease. Group A beta-hemolytic Streptococci, the bacteria that cause "Strep Throat," are considered a possible trigger for the immune system to attack the brain and produce tics or OCD.
The term for this is "PANDAS": Pediatric Auto-immune Neuropsychiatric Disorder Associated with Streptococcal infections. One problem with PANDAS right now is that there is not a specific medical test available that can identify a child who has PANDAS-tics or OCD “caused by Strep”-versus a child who just happened to get Strep throat recently.
Tests for “Strep”
Throat Swabs – swabbing the throat and tonsils: Note - a positive test in a child who is not sick may indicate that the child is a carrier but does not need treatment.
- Rapid test – fairly accurate test in the office used to diagnose strep quickly. May miss some infections.
- Culture – the bacteria on the swab are allowed to grow in the laboratory and tested to see if the Strep bacteria are present.
Antibodies – blood tests for antibodies directed against Strep. These antibodies indicate prior infection or exposure to strep. Note: A positive test does NOT mean that Strep bacteria are in the blood. A positive antibody test means the body has made an immune/antibody response to Strep bacteria it has been exposed to in the past. The level of antibodies is called the titer. Titers at one time, or changes in titers from repeated blood tests, are only useful in selected situations. Checking titers once or repeatedly is not useful for routine care of children with Strep Throat, and not routinely used as part of evaluations of children with tics or OCD. Antibodies can increase or decrease, tests in some laboratories are not always accurate, and different laboratories may use different measurement techniques. Most importantly, antibodies may remain elevated for months or years, so a single blood test for strep antibodies can have very misleading results.
- ASO – this antibody generally is elevated for a period of a few months after a Strep infection.
- DNAse B – this antibody is elevated for longer periods of time, sometimes more than a year after a strep infection.
PANDAS is still a controversial diagnosis, and some physicians are diagnosing it too quickly. At present, PANDAS should NOT be diagnosed after a single episode of Strep Throat followed by tic or OCD symptoms. The PANDAS diagnosis requires two or more episodes of dramatic tic or OCD exacerbations after a proven Strep Infection.
Before we start treating thousands of TS kids with long-term antibiotics, immune suppressing treatments, or tonsillectomies, we need to have more good research. We need to be able to identify which children, specifically, have PANDAS, how bad their symptoms are, and whether treatments cause more benefit than harm.
We recommend that families who think their child's TS symptoms may be caused by strep get evaluated by a physician familiar with the current research on PANDAS. In the meantime, while we do not recommend daily antibiotics or intravenous therapies, we do recommend watching for signs of strep throat. If your child has fever and sore throat or other possible strep symptoms, see your child's primary physician right away.
