About TS > Causes of TS
The cause of TS has not yet been established, although it appears to involve an imbalance in the function of the neurotransmitters (chemical messengers in the brain) dopamine and serotonin. It is also likely to involve abnormalities in other neurotransmitter systems of the brain.
Brain scanning has revealed that there are some areas of the brain that appear to be different in TS individuals, for example some structures in the basal ganglia part of the brain, and in the fronto-temporal brain areas.
In the majority of cases, TS is inherited. A person with TS has roughly a 50 percent chance of passing on the gene to each of their children. However, the child may not inherit the parent’s type of tics, but may show others instead. So far no single gene has been convincingly identified, and exactly how TS is inherited is not clear. The genetics of TS is complex and many researchers now believe that an individual may inherit a vulnerability to a spectrum disorder that includes TS, OCB, and perhaps also ADHD.
Research has shown that diff erent environmental factors may, in some cases, contribute to the onset or affect the severity of TS. Streptococcal throat infections seem to play a role in triggering off TS in some individuals, by causing an abnormal immune reaction. The streptococcus bacteria do not cause TS by itself, but some individuals may well inherit susceptibility to both the syndrome and the way they react to some infections.
Other possible environmental factors that may contribute to the onset or severity of TS include pregnancy and birth related problems such as complications during pregnancy, smoking during pregnancy, severe nausea and/or vomiting during the first trimester and premature low birth weight children.
In conclusion, the cause of TS is complex. All factors mentioned above most likely interact to produce the very special profile of symptoms and severity that is unique to each person with TS.