Causes of Tourette's syndrome

The cause of Tourettes syndrome is unknown. However, it's thought to be linked to problems with an area of the brain known as the basal ganglia.

Basal ganglia

The basal ganglia are a group of specialised brain cells located deep inside the brain. The cells help regulate the body's movements.

Research suggests the basal ganglia may also play a role in higher brain functions such as motivation and decision making.

In people with Tourettes syndrome, it appears tics are the result of a temporary problem occuring inside the basal ganglia which disrupts the decision-making process.

The person suddenly develops an unconscious urge to perform an action (the tic) that the conscious mind regards as both unwanted and unexplained.

It's not known what actually goes wrong with the basal ganglia. One theory suggests excessive levels of a naturally occurring chemical called dopamine, which can have powerful effects on the brain, could be responsible.

Alternatively, the dopamine levels could be normal in people with Tourettes syndrome, but they may be particularly sensitive to its effects.

Brain imaging studies have also shown the structure of the basal ganglia is different in people with Tourettes syndrome. However, it's unclear whether these changes are due to a dopamine imbalance or sensitivity, or the cause of it.

Possible triggers

As with the cause of Tourettes syndrome, it's not known what triggers it. There are several theories, which are outlined below.

Genetics

Genetics appears to play a part in some cases of Tourettes syndrome, as it often runs in families.

Further evidence suggests if one identical twin develops Tourettes syndrome, there's about a one in two chance the other twin will also develop it.

A genetic mutation may disrupt the normal development of the brain, triggering the symptoms of Tourettes syndrome. A genetic mutation is where the instructions contained in all living cells become scrambled in some way.

The antibodies may interact with brain tissue, affecting the brain's functioning.

Following a throat infection, some children have developed the symptoms of Tourettes syndrome, as well as the symptoms of obsessive compulsive disorder (OCD).

Some doctors believe this may be a separate condition in its own right and have called it 'paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections', or PANDAS for short.

However, the concept of PANDAS is controversial because research findings have been inconsistent. It may be that it's only responsible for a small number of Tourettes syndrome cases. Further research is needed to clarify the issue.

In the meantime, the same treatments are recommended as those used in ordinary tic disorders and Tourettes syndrome.