Causes of Tourette Syndrome

Tourette Syndrome (TS) is a complex, neurological condition and it is not yet known what causes it. The condition is hereditary and a person with TS has, roughly, a 50 per cent chance of passing on the gene to their children.

This doesn’t mean, though, that the child will inherit an identical form of TS. Their condition may be milder or more severe than their parents' and they may display different types of tics. So far no single gene has been convincingly identified, and exactly how TS is inherited is not clear.

TS and the brain

The genetics of TS is complex and many researchers believe that an individual can inherit a vulnerability to a spectrum disorder that includes TS, obsessive compulsive disorder, and perhaps also attention deficit hyperactivity disorder.

Although the cause has not been established, 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 individuals with TS, for example some structures in the basal ganglia part of the brain, and in the fronto-temporal brain areas.

Research has shown that different environmental factors may, in some cases, contribute to the onset or affect the severity of TS. These 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.

PANDAS

PANDAS is an abbreviation for Paediatric Autoimmune Neuropsychiatric Associated with Streptococcal infections. This term describes a subset of children who have OCD and/or tic disorders such as TS, and in whom symptoms worsen following strep infections such as ‘strep throat’ and scarlet fever.

Symptoms

With PANDAS, children usually have a dramatic, ‘overnight’ onset of symptoms preceded by a strep throat infection. Symptoms might include: motor or vocal tics, obsessions, and/or compulsions. Associated symptoms include: mood changes, sleep problems, joint pain, urinary frequency and separation anxiety.

A sudden onset of symptoms is often followed by a slow, gradual improvement in symptoms. If they have another strep throat infection, symptoms can return just as suddenly and dramatically as they did before.

Cause

The exact cause behind this phenomenon is not yet known, although it is thought that the mechanism is similar to that of rheumatic fever – an autoimmune disorder triggered by strep throat infections. In the case of PANDAS and TS, it is believed that the antibodies produced to fight the strep throat infection mistakenly recognise and ‘attack’ a part of the brain called the Basal Ganglia, which is believed to be responsible for movement and behaviour. Thus the antibodies interact with the brain to cause tics and/or OCD.

Treatment

The treatment for children with PANDAS is exactly the same for children with OCD and/or Tourette Syndrome.
This information is from the National Institute of Mental Health website.