Tourette’s syndrome is a neurodevelopmental disorder in which patients suffer from tics. It is an inherited disorder where no single gene is involved and the pattern of inheritance is complicated. About half of the patients have a family history of tic disorders. Contrary to the past, TS is now considered a relatively common mental disorder in children. Boys have higher chances of getting TS Stress and anxiety increase the severity of tics in patients already having a tic disorder. A study found that perinatal disturbances are a risk factor for TS.
Tics are sudden movements, sounds, or twitches that a person performs repeatedly without control. Mild tics are not a problem but severe tics can interrupt daily life activities. The severity of tics is maximum during pre-adolescence. In most cases, the severity of these tics decreases with age. The severity of tics is evaluated using the Global Tic Severity Scale Total Tic Score (YGTSS-TTS). Tics can be divided into vocal and motor, or simple and complex tics. When tics result from the contraction of a single muscle or group of closely related muscles, they are called simple tics whereas tics resulting from coordinated contraction of different sets of unrelated muscles are called complex tics.
A variety of comorbidities are seen in almost all TS patients. These comorbidities include:
These comorbidities are the major cause of distress for TS patients and their families.
There’s no single test for the diagnosis of tic disorders. Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-V) gives a set of instructions to diagnose TS. Patients should have at least two motor and one vocal tic every day for more than one year. If tics occur for less than a year, then the patient is suffering from provisional tics disorder. Provisional tics disorder is more common but it goes away before the age of 10. If patients show only one type of tic, then they have a chronic tic disorder. People suffering from various mental disorders other than tic syndrome can also have tics. These disorders include Huntington’s disease, Down’s syndrome, and schizophrenia, and the tics caused by these disorders are called secondary tics.
Treatment is only required when tics are severe enough to disrupt daily activities. Habit reversal treatment is a non-pharmacological and non-invasive technique. It is effective against mild tics in short term. Deep brain stimulation (DBS) is an invasive treatment used as a last resort in severe cases. In this treatment, a pacemaker is placed in the brain to stimulate its specific part. DBS is effective in reducing tics. DBS has serious side effects therefore it should only be used when no other treatment is working.
Alpha agonists are used in treating mild tics. Clonidine and guanfacine are commonly used, alpha agonists. They increase the resistance to blood flow load on the heart. The Food and Drug Administration (FDA) has approved three drugs for the treatment of TS; haloperidol, pimozide, and aripiprazole. These drugs block the receptors of dopamine. Dyskinesia (involuntary and irregular movements) is their major side effect. Vesicular monoamine transporter 2 (VMAT2) used to treat chorea in Huntington’s disease can also be used in TS. Tetrabenazine is a common VMAT2.
All of the options mentioned above are centered around providing symptomatic relief to the patients. The lack of disease-modifying options stems from the fact that the pathophysiology of TS is not entirely understood. More efforts are needed to understand the fundamental mechanisms behind TS so that new therapeutic targets can be identified and disease-modifying drugs can be developed.