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What is known about the nature and diagnosis of Tourette's syndrome? Do we know what causes it, and can it ever be cured?

Jonathan W. Mink, an assistant professor of neurology and anatomy and neurobiology at the Washington University School of Medicine, responds:

"Tourette's syndrome is a neurologic disorder characterized by intermittent, brief involuntary movements or sounds that are called tics. They can range from simple blinking, facial twitches or sniffing sounds to more complex movements and vocalizations. (The involuntary swearing that people commonly associate with Tourette's is actually only one tiny example from the wide variety of symptoms the disorder may produce.) Tics can be quite mild and barely noticeable to an untrained observer or even to the person who has them. They can also be severe enough to interfere significantly with a person's daily activities. In addition to tics, people who have Tourette's syndrome often exhibit obsessions and compulsions, lack of impulse control or attention-deficit disorder.

"It is thought that Tourette's syndrome stems from an abnormality in a part of the brain called the basal ganglia. The exact cause of the abnormality is unknown but is thought to be genetic because most people who show symptoms of Tourette's have other family members who also display such symptoms. The presumed genetic basis of Tourette's is not simple, however, and the syndrome may involve more than one gene. Although Tourette's most likely is a genetic disorder, the symptoms that define the disorder vary considerably, even among members of a single family. There is no 'test' for Tourette's; rather diagnosis is based on the presence of several features that are generally agreed to be essential aspects of the syndrome.

"Just as the cause of Tourette's is unknown, there is also no known cure. There are medications than can be quite effective in reducing the symptoms, however. Different medications are effective for different symptoms. For example, a medication that reduces tics may not help with impulse control or compulsions. Therefore, for each person with Tourette's the choice of medication will depend on which symptoms are the most troubling for that individual. In fact, many people afflicted Tourette's syndrome are able to do well without ever taking any medication at all."

Now Daniel R. Weinberger, chief of the clinical brain disorders branch at the National Institute of Mental Health, has provided some additional information and references:

"Tourette's syndrome is a curious medical condition defined by a constellation of involuntary behavioral manifestations involving abnormal movements and utterances. The abnormal involuntary movements, called motor tics, are repetitive, stereotyped movements, usually of the face and neck. In most cases, they are simple and brief, such as eye blinking, neck jerking, lip smacking or protruding of the tongue. Occasionally the movements are more complex and involve motor routines, such as bending over and touching one's toes or sniffing one's fingers. The utterances, called vocal tics, are also usually brief, stereotyped and repetitive--for instance, throat clearing, snorting, sniffing or grunting. In rare instances, the vocal tics can be complex and involve involuntary repetition of whole phrases, such as parts of the speech of others (echolalia), and swearing (coprolalia).

"Although the tics of Tourette's syndrome are involuntary, they are under a certain degree of conscious control and can be suppressed for varying degrees of time. Interestingly, most affected individuals notice that the longer they suppress their tics, the more they feel an urge to release them. This compulsive quality to the manifestations led Gilles de la Tourette, the 19th-century French neurologist who described the condition, to refer to it as 'tic compulsif.'

"In virutally all cases, Tourette's syndrome begins in childhood, usually before the age of 10. It is a fairly common disorder, occurring in approximately five out of every 10,000 people. This prevalence rate probably underestimates the frequency of milder forms of the disorder, which involve only motor or only vocal tics. Common tic phenomena, such as nervous throat clearing or smacking of the lips, probably represent in many instances milder forms of Tourette's syndrome. In general, the degree and manner of tics tend to vary over time, often being worse during stress or illness. The condition is usually lifelong, but many individuals experience some reduction in the severity of their symptoms as they grow into adulthood. Tourette's syndrome is almost never physically disabling. Most individuals learn to compensate for their symptoms or to accept them as part of their lives and require no or only occasional treatment. The psychological and social aspects of the malady, which can be considerable, represent its main burden.

"The cause of Tourette's syndrome is unknown. Throughout much of this century, it was regarded as a purely psychological condition, but it is now known to be neurological in origin. Family studies and studies of twins have confirmed that there is a genetic basis for the disorder, although the gene or genes have yet to be identified. There is no diagnostic laboratory test for Tourette's syndrome, nor are there unique features that show up in neural imaging techniques, although there are subtle abnormalities in certain brain structures (for example, the caudate nucleus) and neurochemical systems (dopamine, for instance) that have been associated with the disorder. How these findings contribute to the clinical manifestations of the condition is a matter of much speculation.

"It has become increasingly clear that Tourette's syndrome is more than just movements and noises. Many patients also experience the intrusion of involuntary compulsive thoughts and feel the urge to perform repetitive, often illogical acts, such as repetitive counting, checking and hand washing. These obsessive-compulsive symptoms also run in the families of patients with Tourette's syndrome and have led to the belief that the gene or genes underlying the disorder are related to the gene or genes for obsessive-compulsive disorder. The brain regions that have been implicated in Tourette's syndrome also overlap with those that have been linked to obsessive-compulsive disorder. Hence, the two syndromes appear to represent varying manifestations of a common neurobiological spectrum.

"The treatment of Tourette's syndrome is based on the degree of symptoms and distress that individuals experience. Drugs that diminish dopamine activity in the brain (such as haloperidol, pimozide and risperidone) are effective for treating the tics. Serotonin reuptake inhibitors, which are used to treat depression, are also effective in ameliorating the obsessive-compulsive manifestations. Unfortunately, these drugs are not entirely free of side effects, and some individuals find the side effects less tolerable than the tics. Psychological counseling and support groups are often helpful in learning to cope with the social and psychological ramifications of the disorder.

"For most patients with Tourette's syndrome and related tic disorders, the course of treatment is benign and the outcome is good. Future prospects for understanding the basic causes of the disorder and for developing more effective treatments are promising. One of the most important reasons for this optimism is the public education effort and research support of the Tourette's Syndrome Association in Bayside, N.Y. The work of this lay organization has had an enormous impact in reducing the stigma associated with Tourette's syndrome and in making research about this disorder a priority of the biomedical research community."

Dr. Weinberger suggests the following articles for further reading:

The Gilles de la Tourette Syndrome: The Current Status. M. M. Robertson in British Journal of Psychiatry, Vol. 154, pages 147-169; February 1989.

Tourette's Syndrome: A Model Neuropsychiatric Disorder. T. M. Hyde and D. R. Weinberger in Journal of the American Medical Association, Vol. 273, No. 6, pages 498-501; February 8, 1995.

Tourette Syndrome: Prediction of Phenotypic Variation in Monozygotic Twins by Caudate Nucleus D2 Receptor Binding. S. S. Wolfe, D. W. Jones, M. B. Knable et al. in Science, Vol. 273, pages 1225-1227; August 30, 1995.

Quest for the Elusive Genetic Basis of Tourette Syndrome. P. I. Patel in American Journal of Human Genetics, Vol. 59, No. 5, pages 980-982; November 1996

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