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.