The first references in the literature to what might today be classified as Tourette syndrome largely
Although vocal and motor tics are the hallmark of Tourette syndrome, other symptoms such as the expression of socially inappropriate comments or behaviors, obsessive compulsive disorder, attention deficit disorder, self injuring behavior, depression, and anxiety also appear to be associated with Tourette syndrome. Most research suggests that Tourette syndrome is an inherited disorder, although a gene responsible for Tourette syndrome has not yet been discovered.
The cause of Tourette syndrome is unknown although some studies suggest that the tics associated with Tourette syndrome are caused by an increased amount of a neurotransmitter called dopamine. A neurotransmitter is a chemical found in the brain that helps to transmit information from one brain cell to another. Other studies suggest that the defect in Tourette syndrome involves another neurotransmitter called serotonin, or involves other chemicals required for normal functioning of the brain.
It is clear that genetic factors are involved in the occurrence of Tourette syndrome because studies of identical twins (twins who share all the same genes) show that about 85% of the time that one is affected, the other is also affected. One theory is that Tourette syndrome is an autosomal dominant disorder with decreased penetrance. This theory has not been proven and may not be true in all families. An autosomal dominant disorder results from a change in one copy of a pair of genes. Individuals with an autosomal dominant disorder have a 50% chance of passing on the changed gene to their children. Decreased penetrance means that not all people who inherit the changed gene will develop symptoms. There is some evidence that females who inherit the Tourette syndrome gene have a 70% chance of exhibiting symptoms and males have a 99% chance of having symptoms.
Other theories about the cause of Tourette syndrome include the presence of a single gene in combination with other genetic or environmental changes that cause the condition. Some studies have indicated that it is unlikely that there is one genetic change alone that is responsible for causing Tourette syndrome. It is possible that Tourette syndrome has different causes in different individuals. Linkage analysis has been performed by several researchers to identify genes that may be associated with Tourette syndrome. In linkage analysis, researchers determine if people with Tourette syndrome have more markers (identifiable DNA sequences) associated with particular genes in common than would be expected by chance. These studies have indicated several chromosomal locations of interest, including locations on chromosome 2, 4, 5, 7, 8, 10, 11, 13, 17, and 19. In addition, individuals with Tourette syndrome features from different families have been reported to have chromosomal rearrangements that involve chromosome breaks in chromosomes 2, 6, 8, 7, and 18q. The areas where the chromosome broke in these families are under further investigation. More research is needed to establish the cause of Tourette syndrome.
Researchers are also interested in determining if the sex of the parent passing on a particular genetic change for Tourette syndrome influences the occurrence or severity of symptoms. Researchers also want to determine how having a family history of Tourette syndrome in both parents affects the chance for and the severity of the condition in their children.
Tourette syndrome is found in all populations and all ethnic groups, but is three to four times more common in males than females and is more common in children than adults. The exact frequency of Tourette syndrome is unknown, but estimates range from 1–10 in 1,000 children or adolescents.
Motor and vocal tics
The principal symptoms of Tourette syndrome include simple and complex motor and vocal tics. Simple motor tics are characterized by brief muscle contractions of one or more limited muscle groups. An eye twitch is an example of a simple motor tic. Complex motor tics tend to appear more complicated and purposeful than simple tics and involve coordinated contractions of several muscle groups. Some examples of complex motor tics include the act of hitting oneself and jumping. Copropraxia, the involuntary display of unacceptable/obscene gestures, and echopraxia, the imitation of the movement of another individual, are other examples of complex motor tics.
Vocal tics are actually manifestations of motor tics that involve the muscles required for vocalization. Simple vocal tics include stuttering, stammering, abnormal emphasis of part of a word or phrase, and inarticulate noises such as throat clearing, grunts, and high-pitched sounds. Complex vocal tics typically involve the involuntary
The type, frequency, and severity of tics exhibited vary tremendously between individuals with Tourette syndrome. Tourette syndrome has a variable age of onset, and tics can start anytime between infancy and age 18. Initial symptoms usually occur before the early teens, and the mean age of onset for both males and females is approximately seven years of age. Most individuals with symptoms initially experience simple muscle tics involving the eyes and the head. These symptoms can progress to tics involving the upper torso, neck, arms, hands, and occasionally the legs and feet. Complex motor tics are usually the latest onset muscle tics. Vocal tics usually have a later onset then motor tics. In some rare cases, people with Tourette syndrome suddenly present with multiple, severe, or bizarre symptoms.
Not only is there extreme variability in clinical symptoms between individuals with Tourette syndrome, but individuals commonly experience a variability in type, frequency, and severity of symptoms within the course of their lifetime. Adolescents with Tourette syndrome often experience unpredictable and variable symptoms, which may be related to fluctuating hormone levels and decreased compliance in taking medications. Adults often experience a decrease in symptoms or a complete end to symptoms.
A number of factors appears to affect the severity and frequency of tics. Stress appears to increase the frequency and severity of tics, while concentration on another part of the body that is not taking part in a tic can result in the temporary alleviation of symptoms. Relaxation, following attempts to suppress the occurrence of tics, may result in an increased frequency of tics. An increased frequency and severity of tics can also result from exposure to drugs such as steroids, cocaine, amphetamines, and caffeine. Hormonal changes such as those that occur prior to the menstrual cycle can also increase the severity of symptoms.
Other associated symptoms
People with Tourette syndrome are more likely to exhibit non-obscene, socially inappropriate behaviors such as expressing insulting or socially unacceptable comments or socially unacceptable actions. It is not known whether these symptoms stem from a more general dysfunction of impulse control that might be part of Tourette syndrome.
Tourette syndrome appears to also be associated with attention deficit disorder (ADD). ADD is a disorder characterized by a short attention span and impulsivity and, in some cases, hyperactivity. Researchers have found that 21–90% of individuals with Tourette syndrome also exhibit symptoms of ADD, whereas 2–15% of the general population exhibit symptoms of ADD.
People with Tourette syndrome are also at higher risk for having symptoms of obsessive-compulsive disorder (OCD). OCD is a disorder characterized by persistent, intrusive, and senseless thoughts (obsessions) or compulsions to perform repetitive behaviors that interfere with normal functioning. A person with OCD, for example, may be obsessed with germs and may counteract this obsession with continual hand washing. Symptoms of OCD are present in 1.9–3% of the general population, whereas 28–50% of people with Tourette syndrome have symptoms of OCD.
Self-injurious behavior (SIB) is also seen more frequently in those with Tourette syndrome. Approximately 34–53% of individuals with Tourette syndrome exhibit some form of self-injuring behavior. The SIB is often related to OCD, but can also occur in those with Tourette syndrome who do not have OCD.
Symptoms of anxiety and depression are also found more commonly in people with Tourette syndrome. It is not clear, however, whether these symptoms are symptoms of Tourette syndrome or occur as a result of having to deal with the symptoms of moderate to severe Tourette syndrome.
People with Tourette syndrome may also be at increased risk for having learning disabilities and personality disorders and may be more predisposed to behaviors such as aggression, antisocial behaviors, severe temper outbursts, and inappropriate sexual behavior. Further controlled studies need to be performed, however, to ascertain whether these behaviors are symptoms of Tourette syndrome. Individuals with Tourette syndrome are more likely to get migraine headaches and to have sleep disorders, such as difficulty falling asleep, staying asleep, or having unusual movements during sleep.
Tourette syndrome cannot be diagnosed through a blood test. The diagnosis is made through observation and interview of the patient and discussions with other family members. The diagnosis of Tourette syndrome is complicated by a variety of factors. The extreme range of symptoms of this disorder makes it difficult to
- Presence of both motor and vocal tics at some time during the course of the illness.
- The occurrence of multiple tics nearly every day through a period of more than one year, without a remission of tics for a period of greater than three consecutive months.
- Symptoms cause distress or impairment in functioning.
- Age of onset prior to 18 years of age.
- The symptoms are not due to medications or drugs and are not related to another medical condition.
Some physicians critique the DSM-IV criteria, citing that they do not include the full range of behaviors and symptoms seen in Tourette syndrome. Others criticize the criteria since they limit the diagnosis to those who experience a significant impairment, which may not be true for individuals with milder symptoms. For this reason, many physicians use their clinical judgment as well as the DSM-IV criteria as a guide to diagnosing Tourette syndrome.
Treatment and management
There is no cure for Tourette syndrome, and treatment involves the control of symptoms through educational and psychological interventions, behavioral training, and/or medications. The treatment and management of Tourette syndrome vary from patient to patient and should focus on the alleviation of the symptoms that are most bothersome to the patient or that cause the most interference with daily functioning.
Psychological and educational interventions
Psychological treatments such as counseling are not generally useful for the treatment of tics, but can be beneficial in the treatment of associated symptoms such as obsessive-compulsive behavior and attention deficit disorder. Counseling may also help individuals to cope better with the symptoms of this disorder and to have more positive social interactions. Psychological interventions may also help people cope better with stressors that can normally be triggers for tics and negative behaviors. The education of family members, teachers, and peers about Tourette syndrome can be helpful and may foster acceptance and prevent social isolation.
A variety of behavioral training techniques has been suggested and tried in people with Tourette syndrome. Some of these include conditioning techniques (training a person to respond to a particular stimulus with a particular behavior), awareness training, biofeedback training (learning how to control one's involuntary nervous system), and habit reversal. Relaxation therapies have been tried with short-term success. The effectiveness of behavioral training as a whole is not clear.
Many people with mild symptoms of Tourette syndrome never require medications. Those with severe symptoms may require medications for all or part of their lifetime. The most effective treatment of tics associated with Tourette syndrome involves the use of drugs such as Haloperidol, pimozide, sulpiride, and tiapride, which decrease the amount of dopamine in the body. Unfortunately, the incidence of side effects, even at low dosages, is quite high. The short-term side effects can include sedation, dysphoria, weight gain, movement abnormalities, depression, and poor school performance. Long-term side effects can include phobias, memory difficulties, and personality changes. These drugs are therefore better candidates for short-term rather than long-term therapy.
Tourette syndrome can also be treated with other drugs such as clonidine, clonazepam, and risperidone, but the efficacy of these treatments is unknown. In many cases, treatment of associated conditions such as ADD and OCD is often more of a concern than the tics themselves. Clonidine used in conjunction with stimulants such as Ritalin may be useful for treating people with Tourette syndrome who also have symptoms of ADD. Stimulants should be used with caution in individuals with Tourette syndrome since they can sometimes increase the frequency and severity of tics. OCD symptoms in those with Tourette syndrome are often treated with drugs such as Prozac, Luvox, Paxil, and Zoloft.
In many cases, the treatment of Tourette syndrome with medications can be discontinued after adolescence. Trials should be performed through the gradual tapering off of medications and should always be done under a doctor's supervision.
Several areas of the brain have been targeted for surgical approaches to the treatment of severe tic disorders. In addition, deep brain stimulation (using sound waves to stimulate certain areas of the brain) has been suggested as treatment, as there has been some success with this treatment in other movement disorders. Clinical trials are needed to determine the effectiveness and safety of this treatment for possible use in the future.
The prognosis for Tourette syndrome in individuals without associated psychological conditions is often quite good, and only approximately 10% of people with Tourette syndrome experience severe tic symptoms. Approximately 46% of individuals with Tourette syndrome will experience a decrease in the frequency and severity of tics, and another 26% will experience a complete end of symptoms by late adolescence. Fourteen percent will have no change and 14% will have an increase in symptoms. There does not appear to be a definite correlation between the type, frequency, and severity of symptoms and the eventual prognosis. Patients with severe tics may experience social difficulties and may isolate themselves from others for fear of shocking and embarrassing them. People with Tourette syndrome who have other symptoms such as obsessive compulsive disorder, attention deficit disorder, and self-injurious behavior usually have a poorer prognosis.
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Sonja Rene Eubanks, MS, CGC