Causes of Tourett's syndrome

It is considered certain that Tourette's syndrome is caused by a disorder in so-called control circuits of the brain. These control circuits represent connections between different regions of the brain, in particular the frontal brain, the basal ganglia and the limbic system. Furthermore, a disorder in various neurotransmitter systems, in particular the dopaminergic system (both within the basal ganglia and in the forebrain) is considered to be proven in the sense of an overactivity of this system. Drugs that block the binding sites for dopamine (so-called dopamine receptor antagonists) counteract this overactivity and thus presumably lead to a reduction in tics. However, there are probably also changes in other neurotransmitter systems, such as reduced function in the serotonergic system.

Genetics and epigenetic factors

Tic disorders are probably based on a complex inheritance pattern in which various genes contribute to increasing the probability of the disease occurring. Depending on the altered gene locus, a different clinical picture of the disease is likely to result. A promising candidate gene - i.e. a gene with a high probability of being linked to the onset of Tourette syndrome or a tic disorder - is not yet known. For first-degree relatives, the risk of developing Tourette's syndrome is estimated at 5-15%, for tics in general at 10-20%.

In addition to genetic factors, acquired factors (which have not yet been defined) are probably also significant in the manifestation of tic disorders. For example, complications during birth and childhood infections have been considered.

The term PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections) was proposed for patients with tics or compulsions in whom a streptococcal infection could previously be detected in close temporal connection. Whether this should be understood as an independent disease is the subject of controversial debate. It is currently recommended that corresponding treatments (for example with antibiotics or immunomodulating substances) should only be carried out within the framework of studies.

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