Tourette's Syndrome: A critical review
Introduction
Gilles de la Tourette’s Syndrome (TS) is a sporadic or inherited complex neuropsychiatric disorder (not an illness) influenced by neurological, psychological, and sociological factors. It is characterized by involuntary tics - sudden, rapid, recurrent nonrhythmic movements or noises that occur repeatedly in the same way (Temple, 2003). The symptoms include: both multiple motor tics and one or more phonic tics (which may or may not include vocalizations and which sometimes include outbursts of swearing) present at some time during the disorder although not necessarily simultaneously; tics occur many times a day (usually in bouts) nearly every day or intermittently throughout a span of more than one year. Periodic changes are expected in the number, frequency, type and location of the tics; waxing and waning of their severity is also common. Symptoms can sometimes disappear for weeks or months at a time. TS affects about 1 in every 2000 people (Robertson, 1989).
TS syndrome is not considered a mystery anymore, among the circles of neuroscience and clinical psychology, as it has been in the past. On the other hand, there are still some controversial issues regarding this disorder. These are the ways in which Tourette’s should be treated (what medications should be prescribed to people with TS) and the matter whether Tourette’s should be actually considered a Higher Executive Function deficit or not. There is also the issue of the inheritability of the disorder. There is evidence of TS comorbidity with disorders like obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD), a fact which actually suggest inheritability of the disorder, since these disorders are also considered (by most scientists) inheritable. However, as Nass and Bressman (2002) state, the relationships between both ADHD and TS and OCD and TS are complex and not yet clear. In addition to this, until now linkage analysis has pointed to a number of chromosomal locations, but has failed to identify a clear candidate gene(s).
Treating TS
Treating TS has been a controversial issue among scientist for years. The kind of medication that should be prescribed to people with TS is currently under debate mainly because TS is frequently accompanied along with other disorders such as OCD or ADHD. Due to that there is no one medication that is absolutely beneficial for all persons with TS. Moreover, none of the available medications for TS completely eliminates symptoms and in addition, all medications have side effects. Instead, the available TS medications are only able to help reduce specific symptoms.
Some patients who require medication to reduce the frequency and intensity of the tic symptoms may be treated with neuroleptic drugs such as haloperidol and pimozide (Abuzzahab & Brown, 2001). These medications are usually given in very small doses that are increased slowly until the best possible balance between symptoms and side effects is achieved.
Recently scientists have discovered that long-term use of neuroleptic drugs may cause an involuntary movement disorder called tardive dyskinesia (Nass & Bressman, 2002). However, this condition usually disappears when medication is discontinued. Short-term side effects of haloperidol and pimozide include muscular rigidity, drooling, tremor, lack of facial expression, slow movement, and restlessness. These side effects can be reduced by drugs commonly used to treat Parkinson's disease (like ardan or akinitol). Other side effects such as fatigue, depression, anxiety, weight gain, and difficulties in thinking clearly may be more troublesome.
Clonidine, an antihypertensive drug, is also used in the treatment of tics. Studies show that it is more effective in reducing motor tics than reducing vocal tics (Nass & Bressman, 2002). It is also used when treating a child with both ADHD and TS, because it is advisable to avoid the use of stimulant medications in such cases. Still, clonidine is not an “innocent” type of medicine. Fatigue, dry mouth, irritability, dizziness, headache, and insomnia are common side effects associated with clonidine use. Abuzzahab and Brown (2002) mention that fluphenazine and clonazepam may also be prescribed to help control tic symptoms.
When used alone, antidepressant medications are not useful in the treatment of tics. However, TS patients may develop serious depressions, and then the use of antidepressant medication should be considered. In such situations, antidepressants have been added to ongoing TS treatment (haloperidol and clonidine) with good results (Coffey et al., 1998). Complicating the assessment of depression in TS is the fact that pimozide, haloperidol, and clonidine may elicit lowered spirits or dysphoria. Therefore a trial of no medication might be considered before the addition of an antidepressant, especially if the depression emerges soon after the use of another medication and with no apparent psychosocial precipitant.
Medications are also available to treat some of the associated behavioural disorders. Stimulants such as methyphenidate, pemoline, and dextroamphetamine, usually prescribed for ADHD, although somewhat effective, have also been reported to increase tics; therefore their use is controversial (Nass & Bressman, 2002). For OCD that significantly disrupt daily functioning, fluoxetine, clomipramine, sertraline, and paroxetine may be prescribed (Coffey et al., 1998).