A tic is a sudden, uncontrollable movement which can occur anywhere in the body or be vocal. Tics which involve bodily movements are called motor tics whereas tics which involve utterances (such as throat clearing) are called vocal tics. Tics are often very mild and may not be noticeable to others but tics can also be grandiose. It is common for some tics to normally occur in people, particularly children. What separates a normal tic from a tic disorder is that, with a tic disorder, the tics cause significant impairment to the person inflicted.
Types of Tic Disorders
Tic disorders currently make up a category of mental health disorders as defined by the Diagnostic and Statistical Manual of Mental Health Disorders fourth Edition (DSM IV). The DSM IV identifies four types of tic disorders:
- Transient tic disorder: This disorder involves both motor and vocal tics which recur for at least 4 weeks but do not persist for longer than a year.
- Chronic tic disorder: This disorder involves either motor or vocal tics which recur for over a year.
- Tourette’s disorder: This disorder involves both motor and vocal tics which recur for over a year.
- Tic disorder Not Otherwise Specified (NOS): This disorder applies when motor or vocal tics occur but do not meet the definitions of the other three types of tic disorders.
Bodily or vocal tics can occur for a wide range of reasons, including health conditions or drug use. In order to be classified as a mental health disorder, the tics must not be from these external factors. Tic disorders must be severe enough to cause significant impairment to the daily functioning of the person inflicted, such as by affecting schoolwork or relationships. To meet the diagnostic criteria of tic disorders, the tics must present themselves before the patient reaches 18 years of age. In addition to these requirements, each of the types of tic disorder has its own criteria under the DSM IV.
Transient Tic Disorder: To be diagnosed with transient tic disorder, the patient must present at least one vocal and motor tic. These tics occur repeatedly on a regular (nearly daily or more) basis for a minimum of four weeks but do not last longer than a year.
Chronic Tic Disorder: To be diagnosed with chronic tic disorder, tics must be present for at least one year. A patient must have either motor or vocal tics. The tics can be singular or multiple but they must not include both motor and vocal tics. For example, multiple motor tics would qualify as a diagnosis of chronic tic disorder but not motor and vocal tics together.
Tourette’s Disorder: Tourette’s disorder is diagnosed as having at least two motor tics along with at least one vocal tic. The tics do not have to occur at the same time. Tics must be present for at least one year during which the patient was not free of tics for more than three consecutive months.
How Prevalent are Tic Disorders?
Tic disorders usually occur before puberty. They are very common in children with some studies putting the prevalence of 4-24% of school-aged children. Approximately 1% of all people have a tic disorder at some point. Tic disorders are also very common as a comorbid condition, particularly with OCD. Studies estimate that 24-57% of children with OCD also have a tic disorder. Tic disorders also frequently occur with ADHD, sleep disorders, and learning disabilities.
Transient tic disorder is the most common type of tic disorder with chronic tic disorder and Tourette’s disorder being less common.
What Causes Tic Disorders?
In the past, it was largely believed that tic disorders occurred due to emotional duress or traumas. However, experts now largely believe that tic disorders occur as a result of abnormalities in the brain, including imbalances of neurotransmitters. Brain imaging scans also show that people with tic disorders often have abnormal brain activity in certain areas like the Basal ganglia. Malfunctions in these areas could result in tic disorders. There is also evidence which links the onset of tic disorders with streptococcal infections.
How are Tic Disorders Treated?
Before a tic disorder can be treated, it is important to make sure that the tics are not being caused by an underlying medical condition or other external trigger, like drugs or medications. For transient tic disorder and tic disorders with mild symptoms, treatment may not be necessary and the disorder often resolves itself over time.
While there is no medication which is specifically used for treating tic disorders, there are several types of medication which have shown effective in treatment. Antipsychotic, antidepressants, and neuroleptic drugs have shown particularly effective. However, these medications can have side effects so other medications, like hypertension medications, may be used instead. Medications are not typically effective in eliminating tics but they generally reduce the severity and frequency.
Cognitive behavioral therapy is another option for treating tic disorders. Cognitive aspects of therapy may involve self monitoring. Behavioral methods may involve requiring the patient to perform the tic voluntarily for a set duration of time. This has shown to reduce the occurrences of involuntary tics. Behavioral therapy can also involve positive reinforcement in which parents reward children for not performing their tics.
Since tic disorders often occur with other mental health disorders like OCD or ADHD, it is important to determine which disorder is causing the most impairment to the patient and treat this disorder accordingly.
American Psychiatric Association. (2000). Diagnostic and Statistical Manual of Mental Disorders (Revised 4th ed.). Washington, DC: Author.
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“Symptoms Exacerbation of Vocal Tics and Other Symptoms Associated With Streptocococcal Pharyngitis in Patient with Obsessive-Compulsive Disorder and Tics.” American Journal of Psychiatry, 155:1459-1469 (Oct 1998). Web