Tourette Syndrome (TS) is a neurologic condition that usually begins in childhood. Persons with TS have repetitive movements called tics. Often, symptoms of Attention Deficit Hyperactivity Disorder (ADHD), or anxiety disorders such as Obsessive Compulsive Disorder (OCD), are present. All of these symptoms may be due to abnormal function of deep structures in the brain called "the basal ganglia." The cause of TS is unknown.
The Search for a TS Gene in the Brain
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.
Could something in a child's environment trigger 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 new symptoms.
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.
In support of a link between Strep Throat and TS:
- Strep bacteria have proteins on their surface that resemble proteins in the basal ganglia, the part of the brain where tics and OCD are believed to come from. Therefore, in certain people, a strep infection could trigger an auto-immune attack on the brain.
- A neurologic condition called "Sydenham's Chorea" (once referred to as "St. Vitus Dance") occurs after strep throat. Like TS, Sydenham's Chorea starts in childhood, has abnormal involuntary movements, can affect mood, personality, or attention, and is believed to come from abnormal function of the basal ganglia.
- Several medical publications have described children with an explosive onset or worsening of tics, obsessions, and compulsions after strep throat.
Additional research has shown that:
- Most persons with Sydenham's Chorea and some persons with TS have high blood levels of antibodies against Strep, and high blood levels of antibodies that could attack the basal ganglia.
- Patients with either Sydenham's Chorea or TS may have, at least temporarily, some mild enlargement of the basal ganglia, seen on research MRI scans.
- Powerful treatments that suppress the immune system may, at least temporarily, improve OCD or tic symptoms in persons whose symptoms seemed to get worse after strep throat.
This research is exciting and interesting, but so far, it does not prove that Strep causes the immune system to attack the brain and produce tics or OCD. Strep is common. Tics and OCD are common. Therefore, many cases where strep infections occur before tics or OCD worsen could be coincidences.
Recommendations about TS, PANDAS, and strep: Should we treat TS or PANDAS children with antibiotics, immune suppressing treatments, or tonsillectomies?
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, if any, 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 a number of cities around the US, there is a National Institutes of Health-funded study of the possible link between strep throat and tics/OCD that interested families can participate in. In the meantime, while we do not recommend daily antibiotics, 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.
For more information, please contact the Tourette Syndrome Clinic, email@example.com.