Disorders usually first diagnosed in
infancy, childhood, or adolescence.
Tic Disorders--

Tourette syndrome
(also called Tourette's syndrome, Tourette's disorder, Gilles de la Tourette syndrome, GTS or,
more commonly, simply Tourette's or TS) is an inherited neurological disorder with onset in childhood, characterized
by the presence of multiple physical (motor) tics and at least one vocal (phonic) tic; these tics characteristically wax
and wane. Tourette's is defined as part of a spectrum of tic disorders, which includes transient and chronic tics.

Tourette's was once considered a rare and bizarre syndrome, most often associated with the exclamation of
obscene words or socially inappropriate and derogatory remarks (coprolalia). However, this symptom is present in
only a small minority of people with Tourette's.[1] Tourette's is no longer considered a rare condition, but it may not
always be correctly identified because most cases are classified as mild. Between 1 and 11 children per 1,000 have
Tourette's; as many as one in a hundred people may have tic disorders,[2][3] with the more common tics of eye
blinking, coughing throat clearing, sniffing, and facial movements. People with Tourette's have normal life
expectancy and intelligence The severity of the tics decreases for most children as they pass through adolescence,
and extreme Tourette's in adulthood is a rarity. Notable individuals with Tourette's are found in all walks of life.[4]

Genetic and environmental factors each play a role in the etiology of Tourette's, but the exact causes are unknown.
In most cases, medication is unnecessary. There is no effective medication for every case of tics, but there are
medications and therapies that can help when their use is warranted. Explanation and reassurance alone are often
sufficient treatment;[5] education is an important part of any treatment plan.[6]

The eponym was bestowed by Jean-Martin Charcot (1825–93) on behalf of his resident, Georges Albert Édouard
Brutus Gilles de la Tourette (1859–1904), a French physician and neurologist, who published an account of nine
patients with Tourette's in 1885.

Classification

Tics are sudden, repetitive, stereotyped, nonrhythmic, involuntary movements (motor tics) and utterances (phonic
tics) that involve discrete muscle groups.[7] Motor tics are movement-based tics, while phonic tics are involuntary
sounds produced by moving air through the nose, mouth, or throat.

Tourette's is one of several tic disorders, which are classified by the Diagnostic and Statistical Manual of Mental
Disorders (DSM) according to type (motor or phonic tics) and duration (transient or chronic). Transient tic disorder
consists of multiple motor tics, phonic tics or both, with a duration of between four weeks and twelve months. Chronic
tic disorder is either single or multiple, motor or phonic tics (but not both), which are present for more than a year.[7]
Tourette's is diagnosed when multiple motor tics, and at least one phonic tic, are present for more than a year.[8]
Tic disorders are defined similarly by the World Health Organization (ICD-10 codes).[9]

Although Tourette's is the more severe expression of the spectrum of tic disorders,[10] most cases are mild.[11] The
severity of symptoms varies widely among people with Tourette's, and mild cases may be undetected.[7]

Characteristics

Tics are movements or sounds "that occur intermittently and unpredictably out of a background of normal motor
activity",[12] having the appearance of "normal behaviors gone wrong."[13] The tics associated with Tourette's
constantly change in number, frequency, severity and anatomical location. Waxing and waning—the ongoing
increase and decrease in severity and frequency of tics—occurs differently in each individual. Tics also occur in
"bouts of bouts", which vary for each person.[7]

Coprolalia (the spontaneous utterance of socially objectionable or taboo words or phrases) is the most publicized
symptom of Tourette's, but it is not required for a diagnosis of Tourette's. According to the Tourette Syndrome
Association, fewer than 15% of Tourette's patients exhibit coprolalia.[14] Echolalia (repeating the words of others)
and palilalia (repeating one's own words) occur in a minority of cases,[7] while the most common initial motor and
vocal tics are, respectively, eye blinking and throat clearing.[15]

In contrast to the stereotyped movements of other movement disorders (e.g. choreas, dystonias, myoclonus, and
dyskinesias), the tics of Tourette's are temporarily suppressible and preceded by a premonitory urge.[16]
Immediately preceding tic onset, most individuals with Tourette's are aware of an urge[17] that is similar to the need
to sneeze or scratch an itch. Individuals describe the need to tic as a buildup of tension[18] which they consciously
choose to release, as if they "had to do it".[19] Examples of the premonitory urge are the feeling of having
something in one's throat, or a localized discomfort in the shoulders, leading to the need to clear one's throat or
shrug the shoulders. The actual tic may be felt as relieving this tension or sensation, similar to scratching an itch.
Another example is blinking to relieve an uncomfortable sensation in the eye. These urges and sensations,
preceding the expression of the movement or vocalization as a tic, are referred to as "premonitory sensory
phenomena". Published descriptions of the tics of Tourette's identify sensory phenomena as the core symptom of
the syndrome, even though they are not included in the diagnostic criteria.[20][21]

Tics are described as semi-voluntary or "unvoluntary",[12] because they are not strictly involuntary—they may be
experienced as a voluntary response to the unwanted, premonitory urge. A unique aspect of tics, relative to other
movement disorders, is that they are suppressible yet irresistible;[13] they are experienced as an irresistible urge
that must eventually be expressed.[12] People with Tourette's are sometimes able to suppress their tics to some
extent for limited periods of time, but doing so often results in an explosion of tics afterward.[5] People with
Tourette's may seek a secluded spot to release their symptoms, or there may be a marked increase in tics, after a
period
of suppression at school or at work.[13]

Some people with Tourette's may not be aware of the premonitory urge. Children may be less aware of the
premonitory urge associated with tics than are adults, but their awareness tends to increase with maturity.[12] They
may have tics for several years before becoming aware of premonitory urges. Children may suppress tics while in
the doctor's office, so they may need to be observed while they are not aware they are being watched.[22] The
ability to suppress tics varies among individuals, and may be more developed in adults than children.

Although there is no such thing as a "typical" case of Tourette syndrome,[5] the condition follows a fairly reliable
course in terms of the age of onset and the history of the severity of symptoms. Tics may appear up to the age of
eighteen, but the most typical age of onset is from five to seven.[7] The ages of highest tic severity are eight to
twelve (average ten), with tics steadily declining for most patients as they pass through adolescence.[23] The most
common, first-presenting tics are eye blinking, facial movements, sniffing and throat clearing. Initial tics present most
frequently in midline body regions where there are many muscles, usually the head, neck and facial region.[5] This
can be contrasted with the stereotyped movements of other disorders (such as stims and stereotypies of the autism
spectrum disorders), which typically have an earlier age of onset, are more symmetrical, rhythmical and bilateral,
and involve the extremities (e.g., flapping the hands).[24] Tics that appear early in the course of the condition are
frequently confused with other conditions, such as allergies, asthma, and vision problems: pediatricians, allergists
and ophthalmologists are typically the first to see a child with tics.[7]

Among patients whose symptoms are severe enough to warrant referral to clinics, obsessive-compulsive disorder
(OCD) and attention-deficit hyperactivity disorder (ADHD) are often associated with Tourette's. Not all persons with
Tourette's have ADHD or OCD or other comorbid conditions (co-occurring diagnoses other than Tourette's),
although in clinical populations, a high percentage of patients presenting for care do have ADHD.[25] One author
reports that a ten-year overview of patient records revealed about 40% of patients with Tourette's have "TS-only" or
"pure TS", referring to Tourette syndrome in the absence of ADHD, OCD and other disorders.[26] Another author
reports that 57% of 656 patients presenting with tic disorders had uncomplicated tics, while 43% had tics plus
comorbid conditions.[13] "Full-blown Tourette's" is a term used to describe patients who have significant comorbid
conditions in addition to tics.[13]

Causes and origins of Tourette syndrome

The exact cause of Tourette's is unknown, but it is well established that both genetic and environmental factors are
involved.[27] Genetic studies have shown that the overwhelming majority of cases of Tourette's are inherited,
although the exact mode of inheritance is not yet known,[28] and no gene has been identified.[5] In some cases, tics
may not be inherited; these cases are identified as "sporadic" Tourette syndrome (also known as tourettism)
because a genetic link is missing.[29]

A person with Tourette's has about a 50% chance of passing the gene(s) to one of his or her children, but
Tourette's is a condition of variable expression and incomplete penetrance.[30] Thus, not everyone who inherits the
genetic vulnerability will show symptoms; even close family members may show different severities of symptoms, or
no symptoms at all. The gene(s) may express as Tourette's, as a milder tic disorder (transient or chronic tics), or as
obsessive compulsive symptoms without tics. Only a minority of the children who inherit the gene(s) have symptoms
severe enough to require medical attention.[14] Gender appears to have a role in the expression of the genetic
vulnerability; males are more likely than females to express tics.[22]

Non-genetic, environmental, infectious, or psychosocial factors—while not causing Tourette's—can influence its
severity.[5] Autoimmune processes may affect tic onset and exacerbation in some cases. The unproven and
contentious hypothesis that Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal
infections (PANDAS) plays a role in the onset of tic disorders and OCD is a current focus of research.

The exact mechanism affecting the inherited vulnerability to Tourette's has not been established,
and the precise etiology is unknown. Tics are believed to result from dysfunction in cortical and subcortical regions,
the thalamus, basal ganglia and frontal cortex.[27] Neuroanatomic models implicate failures in circuits connecting
the brain's cortex and subcortex,[5] and imaging techniques implicate the basal ganglia and frontal cortex.[33]

Some forms of OCD may be genetically linked to Tourette's.[34] A subset of OCD is thought to be etiologically
related to Tourette's and may be a different expression of the same factors that are important for the expression of
tics.[35] The genetic relationship of ADHD to Tourette syndrome, however, has not been fully established.[26]

Diagnosis

According to the revised fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR),
Tourette’s Disorder may be diagnosed when a person exhibits both multiple motor and one or more vocal tics
(although these do not need to be concurrent) over the period of a year, with no more than three consecutive tic-
free months. The previous DSM-IV included a requirement for "marked distress or significant impairment in social,
occupational or other important areas of functioning", but this requirement was removed in the most recent update
of the manual, in recognition that clinicians see patients who meet all the other criterion for Tourette's, but do not
have distress or impairment.[36] The onset must have occurred before the age of 18, and cannot be attributed to
the "direct physiological effects of a substance or a general medical condition".[8] Hence, other medical conditions
that include tics or tic-like movements—such as autism or other causes of tourettism—must be ruled out before
conferring a Tourette's diagnosis.

There are no specific medical or screening tests that can be used in diagnosing Tourette's;[7] it is frequently
misdiagnosed or underdiagnosed, partly because of the wide expression of severity, ranging from mild (the majority
of cases) or moderate, to severe (the rare, but more widely-recognized and publicized cases).[23] The diagnosis is
made based on observation of the individual's symptoms and family history, and after ruling out secondary causes
of tic disorders.[14] In patients with a typical onset and a family history of tics or obsessive–compulsive disorder, a
basic physical and neurological examination may be sufficient.[10]

If a physician believes that there may be another condition present that could explain tics, tests may be ordered as
necessary to rule out that condition. An example of this is when diagnostic confusion between tics and seizure
activity exists, which would call for an EEG, or if there are symptoms that indicate an MRI to rule out brain
abnormalities.[37] TSH levels can be measured to rule out hypothyroidism, which can be a cause of tics. Brain
imaging studies are not usually warranted.[37] In teenagers and adults presenting with a sudden onset of tics and
other behavioral symptoms, a urine drug screen for cocaine and stimulants might be necessary. If a family history of
liver disease is present, serum copper and ceruloplasmin levels can rule out Wilson's disease.[10] However, most
cases are diagnosed by merey observing a history of tics.[5][14]

Secondary causes of tics (not related to inherited Tourette syndrome) are commonly referred to as tourettism.[29]
Dystonias, choreas, other genetic conditions, and secondary causes of tics should be ruled out in the differential
diagnosis for Tourette syndrome.[10] Other conditions that may manifest tics or stereotyped movements include
developmental disorders, autism spectrum disorders,[38] and stereotypic movement disorder;[39][40] other genetic
conditions such as Huntington's disease, neuroacanthocytosis, Hallervorden-Spatz syndrome, idiopathic dystonia,
Duchenne muscular dystrophy, Wilson's disease, Sydenham's chorea and tuberous sclerosis. Other possibilities
include chromosomal disorders such as Down syndrome, Klinefelter's syndrome, XYY syndrome and fragile X
syndrome. Acquired causes of tics include drug-induced tics, head trauma, encephalitis, stroke, and carbon
monoxide poisoning.[10][29] The symptoms of Lesch-Nyhan syndrome may also be confused with Tourette
syndrome.[24] Most of these conditions are rarer than tic disorders, and a thorough history and examination may be
enough to rule them out, without medical or screening tests.[5]

Screening

Although not all people with Tourette's have comorbid conditions, most Tourette's patients presenting for clinical
care at specialty referral centers may exhibit symptoms of other conditions along with their motor and phonic tics.
[26] Associated conditions include attention-deficit hyperactivity disorder (ADD or ADHD), obsessive–compulsive
disorder (OCD), learning disabilities and sleep disorders.[2] Disruptive behaviors, impaired functioning, or cognitive
impairment in patients with comorbid Tourette's and ADHD may be accounted for by the comorbid ADHD,
highlighting the importance of identifying and treating comorbid conditions.[25][41] Disruption from tics is commonly
overshadowed by comorbid conditions that present greater interference to the child.

Tic disorders in the absence of ADHD do not appear to be associated with disruptive behavior or functional
impairment,[3] while impairment in school, family, or peer relations is greater in patients who have more comorbid
conditions and often determines whether therapy is needed.[13]

Because comorbid conditions such as OCD and ADHD can be more impairing than tics, these conditions are
included in an evaluation of patients presenting with tics. "It is critical to note that the comorbid conditions may
determine functional status more strongly than the tic disorder," according to Samuel Zinner, MD.[5] The initial
assessment of a patient referred for a tic disorder should include a thorough evaluation, including a family history of
tics, ADHD, obsessive–compulsive symptoms, and other chronic medical, psychiatric and neurological conditions.
Children and adolescents with TS who have learning difficulties are candidates for psychoeducational testing,
particularly if the child also has ADHD.[37] Undiagnosed comorbid conditions may result in functional impairment,
and it is necessary to identify and treat these conditions to improve functioning. Complications may include
depression, sleep problems, social discomfort and self-injury.[10]

Treatment of Tourette syndrome

Clonidine (or the clonidine patch) is one of the medications typically tried first when medication is needed for
Tourette's.

The treatment of Tourette's focuses on identifying and helping the individual manage the most troubling or impairing
symptoms.[5] Most cases of Tourette's are mild, and do not require pharmacological treatment;[11] instead,
psychobehavioral therapy, education, and reassurance may be sufficient.[42] Treatments, where warranted, can be
divided into those that target tics and comorbid conditions, which, when present, are often a larger source of
impairment than the tics themselves.[37] Not all people with tics have comorbid conditions,[26] but when those
conditions are present, they often take treatment priority.

There is no cure for Tourette's and no medication that works universally for all individuals without significant adverse
effects. Knowledge, education and understanding are uppermost in management plans for tic disorders.[5] The
management of the symptoms of Tourette's may include pharma-cological, behavioral and psychological therapies.
While pharmacological intervention is reserved for more severe symptoms, other treatments (such as supportive
psychotherapy or cognitive behavioral therapy) may help to avoid or ameliorate depression and social isolation, and
to improve family support. Educating a patient, family, and surrounding community (such as friends, school, and
church) is a key treatment strategy, and may be all that is required in mild cases.[5][43]

Medication is available to help when symptoms interfere with functioning.[14] The classes of medication with the
most proven efficacy in treating tics—typical and atypical neuroleptics including risperidone (trade name[A]
Risperdal), ziprasidone (Geodon), haloperidol (Haldol), pimozide (Orap) and fluphenazine (Prolixin)—can have long-
term and short-term adverse effects.[37] The anti-hypertensive agents clonidine (trade name Catapres) and
guanfacine (Tenex) are also used to treat tics; studies show variable efficacy, but a lower side effect profile than the
neuroleptics.[1] Stimulants and other medications may be useful in treating ADHD when it co-occurs with tic
disorders. Drugs from several other classes of medications can be used when stimulant trials fail, including
guanfacine (trade name Tenex), atomoxetine (Strattera) and tricyclics. Clomipramine (Anafranil), a tricyclic
antidepressant, and SSRIs—a class of antidepressants including fluoxetine (Prozac), sertraline (Zoloft), and
fluvoxamine (Luvox)—may be prescribed when a Tourette's patient also has symptoms of obsessive–compulsive
disorder.[37]

Because children with tics often present to physicians when their tics are most severe, and because of the waxing
and waning nature of tics, it is recommended that medication not be started immediately or changed often.[5]
Frequently, the tics subside with explanation, reassurance, understanding of the condition and a supportive
environment.[5] When medication is used, the goal is not to eliminate symptoms: it should be used at the lowest
possible dose that manages symptoms without adverse effects, given that these may be more disturbing than the
symptoms
for which they were prescribed.[5]

Cognitive behavioral therapy (CBT) is a useful treatment when OCD is present,[44] and there is increasing evidence
supporting the use of habit reversal in the treatment of tics.[45] Relaxation techniques, such as exercise, yoga or
meditation, may be useful in relieving the stress that may aggravate tics, but the majority of behavioral interventions
(such as relaxation training and biofeedback, with the exception of habit reversal) have not been systematically
evaluated and are not empirically supported therapies for Tourette's.[46]

Prognosis

Tourette syndrome is a spectrum disorder—its severity ranges over a spectrum from mild to severe. The majority of
cases are mild and require no treatment.[11] In these cases, the impact of symptoms on the individual may be mild,
to the extent that casual observers might not know of their condition. The overall prognosis is positive, but a minority
of children with Tourette syndrome have severe symptoms that persist into adulthood.[27] A study of 46 subjects at
19 years of age found that the symptoms of 80% had minimum to mild impact on their overall functioning, and that
the other 20% experienced at least a moderate impact on their overall functioning.[7] The rare minority of severe
cases can inhibit or prevent individuals from holding a job or having a fulfilling social life. In a follow-up study of thirty-
one adults with Tourette's, all patients completed high school, 52% finished at least two years of college, and 71%
were full-time employed or were pursuing higher education.[47]

Regardless of symptom severity, individuals with Tourette's can expect to live a normal life span. Although the
symptoms may be lifelong and chronic for some, the condition is not degenerative or life-threatening. Intelligence is
normal in those with Tourette's, although there may be learning disabilities.[14] There is no reliable means of
predicting the outcome for a particular individual. The gene or genes associated with Tourette's have not been
identified, and there is no potential "cure".[14]

Several studies have demonstrated that the condition in most children improves with maturity. Tics may be at their
highest severity at the time that they are diagnosed, and often improve with understanding of the condition by
individuals and their families and friends. The statistical age of highest tic severity is typically between eight and
twelve, with most individuals experiencing steadily declining tic severity as they pass through adolescence. One
study showed no correlation with tic severity and the onset of puberty, in contrast with the popular belief that tics
increase at puberty. In many cases, a complete remission of tic symptoms occurs after adolescence.[23][48]
However, a study using videotape to record tics in adults found that, although tics diminished in comparison with
childhood, and all measures of tic severity improved by adulthood, 90% of adults still had tics. Half of the adults who
considered themselves tic-free still displayed evidence of tics.[47]

It is not uncommon for the parents of affected children to be unaware that they, too, may have had tics as children.
Because Tourette's tends to subside with maturity, and because milder cases of Tourette's are now more likely to be
recognized, the first realization that a parent had tics as a child may not come until their offspring is diagnosed. It is
not uncommon for several members of a family to be diagnosed together, as parents bringing children to a
physician for an evaluation of tics become aware that they, too, had tics as a child.

Children with Tourette's may suffer socially if their tics are viewed as "bizarre". If a child has disabling tics, or tics that
interfere with social or academic functioning, supportive psychotherapy or school accommodations can be helpful.
[14] Because comorbid conditions (such as ADHD or OCD) can cause greater impact on overall functioning than
tics, a thorough evaluation for comorbidity is called for when symptoms and impairment warrant.[10]

A supportive environment and family generally gives those with Tourette's the skills to manage the disorder.[49][50]
People with Tourette's may learn to camouflage socially inappropriate tics or to channel the energy of their tics into
a functional endeavor. Accomplished musicians, athletes, public speakers, and professionals from all walks of life
are found among people with Tourette's. Outcomes in adulthood are associated more with the perceived
significance of having severe tics as a child than with the actual severity of the tics. A person who was
misunderstood, punished, or teased at home or at school will fare worse than children who enjoyed an
understanding and supportive environment.[7]

A controlled study on a small group of individuals with Tourette's found that young people with the syndrome have
greater cognitive control over movements than their age-matched controls, possibly because the need to suppress
tics results in a more efficient control over inhibitory movements, a skill that confers an advantage when switching
between tasks. Children with Tourette's (in the absence of comorbid ADHD) performed more accurately on a goal-
oriented eye-movement task, requiring active inhibition of automatic eye movements, and they made fewer errors
than their unaffected peers, suggesting compensatory changes in the brain resulting in greater cognitive control.
[51] A subsequent study confirmed and extended the paradoxical result that individuals with Tourette's exhibit
greater levels of cognitive control than age-matched healthy peers.[52] A study of eight children, age 8–17, found
that children with Tourette syndrome were quicker at processing certain mental grammar skills than are children
without the condition. The abnormalities that lead to tics may also lead to "other rapid behaviors, including the
cognitive processing of rule-governed forms in language and other types of procedural knowledge".[53]

Epidemiology

Tourette syndrome is found among all social, racial and ethnic groups,[2][54] has been reported in all parts of the
world,[55] and is three to four times more frequent among males than among females.[56] The tics of Tourette
syndrome begin in childhood and tend to remit or subside with maturity; thus, a diagnosis may no longer be
warranted for many adults, and prevalence is much higher among children than adults.[23] Children are five to
twelve times more likely than adults to be identified as having tic disorders;[57] as many as 1 in 100 people
experience tic disorders, including chronic tics and transient tics in childhood.[2]

Discrepancies across current and prior prevalence estimates come from several factors: ascertainment bias in
earlier samples drawn from clinically referred cases, assessment methods that may fail to detect milder cases, and
differences in diagnostic criteria and thresholds.[58] There were few broad-based community studies published
before 2000 and until the 1980s, most epidemiological studies of Tourette syndrome were based on individuals
referred to tertiary care or specialty clinics.[1][59] Children with milder symptoms are unlikely to be referred to
specialty clinics, so these studies have an inherent bias towards more severe cases.[1][60] Studies of Tourette
syndrome are vulnerable to error because tics vary in intensity and expression, are often intermittent, and are not
always recognized by clinicians, patients, family members, friends or teachers;[5][61] approximately 20% of persons
with Tourette syndrome do not recognize that they have tics.[5] Recent studies—recognizing that tics may often be
undiagnosed and hard to detect—use direct classroom observation and multiple informants (parent, teacher, and
trained observers), and therefore record more cases than older studies relying on referrals.[62][43] As the
diagnostic threshold and assessment methodology have moved towards recognition of milder cases, the result is an
increase in estimated prevalence.[58]

Tourette syndrome was once thought to be rare: in 1972, the US National Institutes of Health (NIH) believed there
were fewer than 100 cases in the United States,[63] and a 1973 registry reported only 485 cases worldwide.[64]
However, multiple studies published since 2000 have consistently demonstrated that the prevalence is much higher
than previously thought.[65] The emerging consensus is that 1–11 children per 1,000 have Tourette's, with several
studies supporting a tighter range of 6–8 children per 1,000.[3] Using year 2000 census data, a prevalence range of
1–10 per 1,000 yields an estimate of 53,000–530,000 school-age children with Tourette's in the US[3] and a
prevalence range of 6–10 per 1,000 means that 64,000–106,000 children aged 5–18 years may have Tourette's in
the UK.[43] Most of these children are undiagnosed and have mild symptoms without distress or impairment.[55][62]


Tic disorders are defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM) based on type (motor
or phonic) and duration of tics (sudden, rapid, nonrhythmic, stereotyped, involuntary movements). Tic disorders are
defined similarly by the World Health Organization (ICD-10 codes).

Classification

Tic disorders are classified as follows:

* Transient tic disorder consists of multiple motor and/or phonic tics with duration of at least 4 weeks, but less than
12 months.
* Chronic tic disorder is either single or multiple motor or phonic tics, but not both, which are present for more than a
year.
* Tourette's disorder is diagnosed when both motor and phonic tics are present for more than a year.
* Tic Disorder NOS is diagnosed when tics are present, but do not meet the criteria for any specific tic disorder.

Tic disorders onset in childhood (before the age of 18), and are not due to the effects of medication or another
medical condition.

Prevalence

A large, community-based study suggested that over 19% of school-age children have tic disorders.[4] The children
with tic disorders in that study were usually undiagnosed. (Kurlan) As many as 1 in 100 people may experience
some form of tic disorder, usually before the onset of puberty. (NIH) Tourette syndrome is the more severe
expression of a spectrum of tic disorders, which are thought to be due to the same genetic vulnerability.
Nevertheless, most cases of Tourette syndrome are not severe. Although a good body of investigative work
indicates genetic linkage of the various tic disorders, further study is needed to confirm the relationship.[5]

Treatment

Treatment of tic disorders, although not usually necessary, is similar to treatment of Tourette syndrome. Tics should
be distinguished from other causes of tourettism.


References

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249–53. PMID 12087644 Full text (free registration required).
2. ^ National Institute of Neurological Disorders and Stroke/National Institutes of Health (NINDS/NIH). Tourette Syndrome Fact Sheet.
2007-02-14. Retrieved on May 14, 2007.
3. ^ Scahill L, Williams S, Schwab-Stone M, Applegate J, Leckman JF. Disruptive behavior problems in a community sample of children
with tic disorders. Adv Neurol. 2006;99:184-90. PMID 16536365
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5. ^ Zinner (2000).
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59 Suppl 1:62–72; discussion 73–4. PMID 9448671 Full text, archived May 25, 1998. Quote: "Because of the understanding and hope
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PMID 16536348
8. ^ BehaveNet. Tourette's disorder. Retrieved on May 14, 2007.
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