Tourette Syndrome

From Science Online

Contents 1 Introduction 2 Symptoms 3 Tics 4 Tic Suppression 5 Possibly Related Disorders 6 Testing 7 Is there treatment? 8 How do I know if have Tourette Syndrome? 9 Protein Structure 10 Biochemistry

Introduction

(Tourette Syndrome Association of Greater New York State)

French neurologist Georges Gilles de la Tourette first found the symptoms of Tourette Syndrome in 1885. The suggestion was made that the disorder was hereditary, however, it wasn't until the 1970's that Tourette Syndrome was officially named to be a disorder. The disorder is caused by a change in the makeup of the chromosomes or genes in a person's body. Because the disorder is thought to be hereditary, carriers of the disease have the chance of passing it down to their children, however, the symptoms do not begin to appear until the child is between six to nine years old. Three symptoms are seen throughout cases of Tourette's Syndrome. The most common symptom is Coprolalia, the other two being Echolalia and palilalia. Coprolalia is the spontaneous outbursts of confrontational phrases, words, and sayings. Echolalia is the repetition of words that are said from other people. Palilalia is the repetition of one's own words. The number of motor and vocal tics that can occur in the victim everyday can range from several times per minute to only a few times a day. Some commonly seen vocal tics include grunting, the clearing of the throat, saying words or phrases, and making loud sounds. The tics tend to increase until they reach their peak around the puberty years of the victim, and then begin to decrease and taper off. However, if a parent with Tourette Syndrome passes it down to a child and symptoms do not show around that age then it doesn't mean the child doesn't have it. The tics can occur as late as age 21 in the child's life. The Tourette Syndrome Association reports that in about 70% of Tourette Syndrome cases, the tics disappear when the child reaches the age of 20 to 24. However, if the tics do not seem to stop by then, the tics seem to continue throughout the rest of their lives. Some children display periods of time, ranging from a couple of days to even a year, where they will not experience any tics at all. (Tourette Syndrome Association)

Symptoms

There are several symptoms that can denote whether or not you have Tourette Syndrome. The most common symptoms are facial tics and involuntary sounds. Sometimes the word "involuntary" can be misleading as some victims of Tourette Syndrome report to have control over their symptoms and tics. It's thought to be that the facial tic is seen first, however, the involuntary sounds could possibly be the initial signs of Tourette Syndrome. Facial tics can be rapidly blinking eyes or even twitches of the mouth. Involuntary sounds are throat clearing and sniffing. Another common symptom are tics of the limbs.

The Tourette Syndrome Foundation of Canada has said that symptoms may include any of the following as well: both multiple motor and one or more vocal tics present at some time during the illness; the occurance of tics multiple times a day (almost every day or throughout at span of more than a year); the periodic change in the number, frequency, type and location of the tics, disappear for weeks or months at a time; onset before the age of eighteen.

(Tourette Syndrome Foundation of Canada)

Tics

Motor tics can be generally categorized by the following:

eye blinking, head jerking, shoulder shrugging, facial grimacing, jumping, touching other people, touching other objects, smelling, twirling about, self-injurious actions

Vocal tics can be generally categorized by the following:

throat clearing, yelping, sniffing, tongue clicking, saying ordinary words or phrases out of context, echolalia, coprolalia

(Tourette Syndrome Foundation of Canada)

Tourette Syndrome tics are categorized into simple and complex. Simple tics are considered to be brief movements involving only a couple of muscle groups, often ocurring in either an isolated manner or in a repetitive manner. Complex tics are patterns of successive movements that involve several muscle groups. Vocal tic symptoms could possibly interfere with speech in everyday conversation, however, most of the time they occur start of a sentence. Motor tic symptoms may or may not occur with vocal tic symptoms. (Tourette Disorder)

Tic Suppression

Recent studies have been conducted in order to find out the different ways that the chronic tic disorder can be suppressed. Results have now given scientists reason to believe that throughout the three different durations that was tested, the tics were suppressed throughout each one and no side effects were noted throughout the durations either. (Woods, 2008)

(Tourette Syndrome Association)

(Tourette Syndrome Foundation of Canada)

Possibly Related Disorders

There are several other disorders found commonly in children and victims of Tourette Syndrome. Many have been found to have Attention Deficit Disorder (ADD), Attention Deficit Hyperactivity Disorder (ADHD), and Obsessive Compulsive Disorder (OCD). (Tourette Syndrome Association) For children, Attention Deficit Hyperactivity Disorder is identified by any of the following symptoms: difficulty in concentration, unable to finish what is started, easily distracted, seeming that he/she is not listening, acting before thinking, overwhelmed or frustrated, constantly shifting from one activity to another, necessity of a lot of supervision, fidgeting. For adults, Attention Deficit Hyperactivity Disorder is identified by any of the following symptoms: over impulsive behavior, concentration difficulties, constantly needing to move. Those who struggle with Attention Deficit Disorder without Hyperactivity experience the same symptoms, however, involve less activity. Victims with Tourette Syndrome may also suffer from sleep disorders, learning disabilities such as dyslexia, and may struggle with controlling their impulses. (Tourette Syndrome Foundation of Canada)

Testing

Different varieties of testing have been administered to those that have Tourette's Syndrome in efforts to advance further knowledge about the Syndrome. One type of testing involved the influences that certain foods and drinks have on a person's tics. A questionaire shows that 34% think that coffee deteriorates tics and that 47% believe that coke deteriorates tics. This questionaire is an example to how researchers come up with new theories, this example showing that caffeine may be a stimulant for tics.

Is there treatment?

What causes Tourette Syndrome remains to be unknown to this day, as researchers are still searching for the answer. Because of this, a common question regarding Tourette Syndrome is whether or not there are medications for it. The tics of the victims can often be controlled or minimized by certain medication. However, appropriate dosage levels are crucial to determine and because of this, it is wise to find a doctor that has dealt with Tourette Syndrome and is extremely familiar with the disorder. There isn't a single type of medicine that has been produced specfiically to cure or taper Tourette Syndrome. In 2000, however, Layton Biosciences was given approval from the FDA to use a type of nicotine patch (to treat Tourette Syndrome) with traditional drugs (to treat tics), such as Haldol, for victims with Tourette Syndrome tics. (Tourette Syndrome Association, Inc.) Haldol is a neuroleptic medication often given to those to help lessen motor and phonic tics because it alters the effects of dopamine in the brain. Drugs that are similarly used to Haldol are Orap, Prolixin, Navane, and Thorazine. (Tourette Syndrome Association)

How do I know if have Tourette Syndrome?

Blood analysis, x-ray, or other types of medical tests that are commonly used to identify diseases and disorders aren't used to identify Tourette Syndrome. There is no test similar to these that exists in order to identify Tourette Syndrome either. There is, however, a couple of options that victims do have in order to become a step closer to identifying Tourette Symdome. One option is that the doctor could order an Elecroencephalogram (EEG) scan. A second option is that the doctor could order a Computerized Axial Tomography (CAT) scan. A third option for doctors are to have several different blood tests. These options may not specifically identify Tourette Syndrome, however, they are able to rule out other ailments that could be confused with Tourette Syndrome.

Check Lists are used to record symptoms over a period of time. This is important in the diagnosis process in order to ensure consistency in the symptoms. There are three check lists that are commonly used in order to check symptoms. The Tourette Syndrom Foundation of Canada offers three check lists on their website in order for those who suspect symptoms of Tourette Syndrome to analyze and consider seeing a doctor. The website has a check list for TIC Symptoms (Motor), ADHD Symptoms, and OCD Symptoms.

(Tourette Syndrome Foundation of Canada)

Protein Structure

Top line, from left to right: Dopamine, Serotonin

Bottom line: Norepinephrine

Tourette's Syndrome is a neurological disorder. Therefore, Dopamine, Serotonin, and Norepinephrine are all found and affected in the brain. Norepinephrine is one of the brain's neurotransmitters that is involved in creating and the function of dopamine and serotonin. (Tourette Syndrome Association, Inc.)

Dopamine: Dopamine is one of the neurotransmitters that is responsible and involved in the transmission of information from one nerve cell to another nerve cell. If this transmitter fails to function normally, it may be responsible in part for causing the tics that victims of Tourette Syndrome experience. (Tourette Syndrome Association, Inc.) It is thought by researchers and scientists that dopamine-stimulated drugs are what cause and set off the tics that a person who has Tourette's syndrome has. They believe that the dopamine receptors react to chemicals because they are highly sensitive, causing tics. There is also a possibility that those who have Tourette's syndrome experience tics because of a higher use and production of dopamine in their brain. [1] (Society of Neuroscience)

Serotonin: When off balance, it is thought to be involved in causing the symptoms of depression and even Obsessive Compulsive Disorder. (Tourette Syndrome Association, Inc.) It has been established by scientists that patients with Tourette's Syndrome commonly found with obsessive and compulsive habits. This is why tryptophan is now being considered as one of the possible areas(Rippel, 2006) that Tourette's Syndrome may be present. This gives hope to the future, as research is now being conducted in order to find treatment for this area of the brain that contains serotonin. [2] (CERI)

Norepinephrine: Recent studies are showing that patients with Tourette's Syndrome lacking attention-deficit hyperactivity were linked with two types of the norepinephrine transporter gene. [3] (PubMed)

Biochemistry

Tourette Syndrome is a hetergeneous disorder. Research studies are now able to tell us that the cortico-striato-thalamo-cortical pathways are the origin to which Tourette syndrome begins and expands. The cortico-striato-thalamo-cortical pathways are responsible of controlling one's behavior. Stanislas Dehaene and Laurent Cohen performed several studies on patients that have shown that these pathways effect the sequences of words.(Dehaene) Magnetic Resonance Imaging has compared the controls to patients of Tourette syndrome and have recently confirmed that these cortical pathways are a serious possibility to be the cause of these tics. In dealing with the cortico-striato-thalamo-cortical pathway abnormality, researchers are suggesting that the basal ganglia is involved with causing the tics. The Magnetic Resonance Imaging tests have supported the involvement of this as well. The basal ganglia is deep in the brain and relays messages between the cortex and lower structures of the brain. (Tourette Syndrome Association, Inc.) There are suggestions that the cause of the mutations in the basal ganglia are caused by abnormalities that are occurring in its major fiber pathways and by lesions in other parts of the brain that are interconnected with the basal ganglia. (Singer, 2003) Researchers at the National Institute of Mental Health have been able to relate an aspect of the disorder to the caudate nucleus after studying a pair of identical twins. The caudate nucleus is a region of the brain that delas with control of voluntary movements and obsessive and compulsive behaviors.

(Society of Neuroscience)

(Wikipedia)

Without a doubt, Tourette Syndome is a neurological disorder, meaning that the effects the syndrome has on the patients is controlled, expands, and begins in the brain. Though the true cause of Tourette Syndrome is unknown, there are strong suggestions to where and what causes the syndrome. Dopamine, Serotonin, and Norepinephrine are all being considered to be the receptor genes that are being altered, resulting in the syndrome.

An abnormality in the dopamine receptor genes are thought to be involved in causing Tourette Syndrome because of the way the genes are responding to the neuroleptic medications that are given to suppress tics and other symptoms of Tourette Syndrome. Dopaminergic neurotransmitters can adjust cortico-striatal transmission. This modulation can possibly either strengthen or weaken the power to produce an effect of cortico-striatal synapses and mediate reinforcement of certain discharge patterns. (Singer, 2003) Synapses are gaps between neurons in which messages are carried across by neurotransmitters. (Tourette Syndrome Association, Inc.) It has been hypothesized by Harvey S. Singer and Karen Minzer, of the Department of Neurology and Pediatrics at Johns Hopkins University, that dopaminergic-induced fluctuating abnormalities in the resting potential of striatal neurons influence tic waxing and waning. (Singer, 2003) Waxing and waning is defined as a naturally occurring fluctuation in severity and frequency of Tourette Syndrome symptoms. (Tourette Syndrome Association, Inc.) There is also a possibility that these dopaminergic-induced fluctuating abnormalities can be the explanation to the why there is a lack of indentifiable abnormality in dopaminergic transmission. (Singer, 2003)

Serotonin regulates the motor, sensory, and cortical functions throughout different subtypes of 5HT receptors. A total of fifteen receptor genes have been identified, a part of the F protein-coupled receptor family. Serotonin is being considered as one of the causes of Tourette Syndrome because of its relation with Obsessive Compulsive Disorder. Studies support a role in causing the symptoms of Obsessive Compulsive Disorder. Because Obsessive Compulsive Disorder is commonly found in children or adults that are victims of Tourette Syndrome, it is thought that the alteration of this transmitter should not be ruled out to potentially cause the disorder.(Singer, 2003)

(Lam, 1996)

A recent test on the DNA of a Tourette Syndrome patient shows that a Serotonin Receptor Gene, 5HT1A, produces a variant form of the 5HT1A receptor (Arg219 to Leu). This amino acid that is present in the receptor is found in the cytoplasmic loop between TM5 and TM6. This area is also know thought to be involved in the grouping of G-proteins. The figure above shows the response that the dose has against the serotonin, and the mutated form of the receptor that it causes. A second mutation (AAC1254 to AAG) was found in the samples as well, where a lysine has taken place in the rat 5HT1A. Tests following this allowed researchers to discover another amino acid change (Asn417 to Lys) in the carboxyl tail of the receptor. (Lam, 1996) Three nucleotide sequence variants have been discovered so far, two of which create amino acid sequence changes and the other being a silent mutation. (Singer, 2003)

References