Tourette Syndrome Health Article

Definition

Tourette syndrome (TS) is an inherited disease of the nervous system, first described more than a century ago by a pioneering French neurologist, George Gilles de la Tourette. Before they are 18 years of age, patients with TS develop motor tics; that is, repeated, jerky, purposeless muscle movements in almost any part of the body. Patients also develop vocal tics, which occur in the form of loud grunting or barking noises, or in some cases words or phrases. In most patients, the tics come and go, and are often replaced by different sounds or movements. The tics may become more complex as the patient grows older.

Description

TS is three times more common in men than in women. The motor tics, which usually occur in brief episodes several times a day, may make it very hard for the patient to perform such simple acts as tying shoelaces, not to mention work-related tasks or driving. In addition, TS may have negative effects on the patient's social development. Some patients have an irresistible urge to curse or use offensive racial terms (a condition called coprolalia), although these impulses are not under voluntary control. Other people may not enjoy associating with TS patients. Even if they are accepted socially, TS patients live in fear of offending others and embarrassing themselves. In time, they may close themselves off from former friends and even relatives.

It is important to note, however, that the symptoms of Tourette syndrome are not always dramatic and are often overlooked in people with mild cases of the disorder. A 2001 report published in Pain & Central Nervous System Week, in fact, states that TS is much more common than doctors had thought. A study of 1,596 special-education children in Rochester, NY, found that 8% met the criteria for TS, and 27% had a tic disorder. In Rochester's general population, 3% were found to have Tourette syndrome, and 20% had a tic disorder. The rate of 3% in the general population is 50–75 times higher than the usual estimates given.

The tics of TS are often described as involuntary, meaning that patients cannot stop them. This description is not strictly true, however. A tic is a very strong urge to make a certain motion or sound. It is more like an itch that demands to be scratched. Some patients are able to control their tics for several hours, but once they are allowed expression, they are even stronger and last longer. Tics become worse when the patient is under stress, and usually are much less of a problem during sleep.

Some people with TS have trouble paying attention. They often seem grumpy and may have periods of depression. TS patients may think the same thoughts over and over, a mental tic known as an obsession. It is these features that place TS patients on the border between diseases of the nervous system and psychiatric illness. In fact, before research showed that the brains of TS patients undergo abnormal chemical changes, many doctors were convinced that TS was a mental disorder. It still is not clear whether these behaviors are a direct result of TS itself or a reaction to the stress of having to live with the disease.

Causes

Tourette syndrome has been linked to parts of the brain known as the basal ganglia, which regulate movements and are involved in concentration, paying attention, and decision-making. Research has also demonstrated that in TS there is a malfunction in the brain's production or use of important substances called neurotransmitters. Neurotransmitters are chemicals that control the signals that are sent along the nerve cells. The neurotransmitters dopamine and serotonin have been implicated in TS; noradrenaline is thought to be the most important stimulant. Medications that mimic noradrena-line may cause tics in susceptible patients.

TS has a genetic component. If one parent has TS, each child has a 50% chance of getting the abnormal gene. Seven of every 10 girls who inherit the gene, and nearly all boys who inherit it, will develop symptoms of TS. Overall, about one in every 2,500 persons has full-blown TS. Three times as many will have some features, usually chronic motor tics or obsessive thoughts. Patients with TS are more likely to have trouble controlling their impulses, to have dyslexia or other learning problems, and to talk in their sleep or wake frequently. Compulsive behavior, such as constantly washing the hands or repeatedly checking that a door is locked, is a common feature of TS. Compulsions are seen in 30–90% of all TS patients.

Recent research findings suggest that Tourette syndrome may also be related to an autoimmune response. A subset of TS patients have symptoms triggered by infection with Group A beta-hemolytic streptococci. In addition, blood serum antibodies against human basal ganglia have been found in patients with TS.