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Tourette Syndrome

Overview

Tourette syndrome (aka Gilles de la Tourette) is a tic disorder that consists of motor and vocal tics, as well as associated sensory and cognitive premonitory urges. The disorder typically onsets during childhood, and many people eventually outgrow their tics. There is no evidence of cognitive impairment in individuals with only Tourette syndrome. However, the majority of patients have comorbid psychopathology, such as obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD), which are associated with cognitive dysfunction. There is currently no cure for Tourette syndrome; however, there are a variety of behavioral and pharmacological interventions available.

 

Symptoms and Typology

According to the European Society for the Study of Tourette Syndrome (ESSTS), tics are “sudden, rapid, recurrent, non-rhythmic motor movements or vocalizations usually appearing in bouts while waxing and waning in frequency, intensity and kind of tic.” Tourette syndrome may include motor (e.g., eye blinking) and vocal (aka phonic tics; e.g., throat clearing, high-pitched sounds) tics. People with this disorder also experience sensory and cognitive premonitory urges before the tics, such as itch, pressure, and repetitive, non-anxious thoughts. What is often associated with Tourette syndrome – yelling out inappropriate words (called coprolalia) – is only present in 14-20% of individuals with this disorder. People may be able to suppress their tics, although the suppression is accompanied by discomfort and an urge to execute the tic (1).

 

Tics can be simple or complex. Simple tics implicate one muscle or muscle group (e.g., eye blinking, throat clearing), while complex tics usually involve repetitive and/or compulsive movements or sounds (e.g., repetitive touching of objects or people, expressing obscenities). However, it may be difficult to distinguish between complex tics and OCD symptoms (1).

 

In terms of cognitive functioning, children with “uncomplicated” Tourette syndrome (without comorbid psychopathology) do not evidence any cognitive difficulties (1). In fact, a research study has demonstrated that these children excel on tasks of behavioral inhibition, which may be a result of long-term tic suppression (2). However, this finding still needs to be replicated and confirmed. On the other hand, for children with comorbid Tourette syndrome and ADHD, they demonstrate weaknesses in attention and executive functions (i.e., higher-order cognitive abilities such as planning, inhibition, and cognitive flexibility) as well as learning disabilities. There is less evidence for cognitive dysfunction in children with Tourette syndrome and OCD. In general, these children may have difficulties with executive functioning (1).

 

Neuroimaging

The exact pathologic mechanism for Tourette syndrome is not well established, and many neuroimaging findings are mixed. Some structural imaging studies have identified volume changes/asymmetry of the basal ganglia (brain region involved in movement) in both children and adults with Tourette syndrome. Volume changes in cortical brain areas (parts involved with higher-order cognitive processing), such as the frontal and parietal regions (particularly prefrontal, sensorimotor, and anterior cingulate cortices), as well as the occipital lobe have been observed (3). A small number of studies have also pointed towards dysfunction of the thalamus (sensory and motor relay station in the brain). Abnormalities in the connections between cortical regions and the basal ganglia (4) as well as between the left and right hemispheres of the brain (5) are also suggested. Functional imaging studies have correlated activities in similar regions with tic occurrence/severity and tic suppression (3).

 

In terms of neurochemicals, dopamine dysfunction is considered to be an important mechanism, which informs pharmacological treatments, such as the use of dopamine-blocking agents (i.e., antipsychotics). However, Tourette syndrome is likely dependent on multiple neurochemical systems. Other neurotransmitters, such as serotonin, glutamate, GABA, and acetylcholine have been implicated as well (3).

 

Prevalence

The prevalence of Tourette syndrome is estimated to be 0.3-0.6% among children and adolescents in the U.S. (6). However, this may be an underestimate because the diagnosis is often missed, and the average time from symptom onset to actual diagnosis is five years (1). Prevalence is higher among boys than girls (three to five times higher). Non-Hispanic white children have twice the rate as other children. Adolescents (age 12 – 17) are twice as likely to have the diagnosis compared to younger children (age 6 – 11) (6). There is a 10- to 100-fold increase in incidence of Tourette syndrome when there is a family history of the disorder in first-degree relatives (1).

 

Course

Onset is typically during childhood (around age five or six). Motor tics usually develop before vocal tics. Eighty percent of children experience a reduction in symptoms during adolescence and early adulthood. For some, the tics may disappear altogether. However, for 20% of these children, tics may worsen over time. Tourette syndrome is highly comorbid with OCD and ADHD. OCD symptoms tend to develop after the occurrence of tics (and remit in 40% of individuals), and ADHD symptoms are likely to develop before tic onset (and decrease in 20%) (1).

 

Treatments

There is currently no cure for Tourette syndrome. However, there is a variety of treatments to reduce symptoms. The first step is psychoeducation about tics while implementing a “watch and wait” strategy. For many people, psychoeducation is sufficient; however, more treatment may be needed if the syndrome begins to cause significant impairment in daily life (7).

 

Clinical trials for pharmacological treatments are scarce. Based on extant literature, the best evidence lies with typical antipsychotic medications (e.g., haloperidol and pimozide). Atypical antipsychotics (e.g., risperidone) may also be used with the assumption of a lower risk for adverse side effects (7).

 

Various behavioral interventions have been applied to the treatment of Tourette syndrome. Habit reversal training (HRT; trains the individual to become aware of tics and execute an alternative response until the urge passes) and exposure with response prevention (ERP; helps the person unlearn the association between tics and urges) are the most efficacious at reducing tics.  Other methods, such as contingency management and function based interventions, which involve manipulating the environment to reward tic-free periods and ignore tic behaviors, can complement HRT and ERP. Relaxation training to reduce stress and anxiety (which may exacerbate tics) may also be used. Neurofeedback is a potentially effective treatment option, although evidence for its efficacy is still limited (8).

 

Deep brain stimulation (DBS; surgically implanting an electrode in the brain to stimulate a certain part of the brain) of the thalamus is an alternative option for adult patients who do not respond to other non-invasive treatments. Unlike other neurological disorders such as Parkinson’s disease, DBS in Tourette syndrome is still considered experimental.  More large scale clinical trials need to be conducted (9).

 

A separate article using neurofeedback for treating Tourette’s is on this website.

 

— By M Chen & J Thomas

 

References

  1.  Cath, D, Hedderly, T, Ludolph, A, Stern, J, Murphy, T, Hartmann, A & Rizzo, R (2011). European clinical guidelines for Tourette syndrome and other tic disorders. Part I: assessment. European child & adolescent psychiatry, 20(4), 155-171.
  2.  Mueller, S, Jackson, G, Dhalla, R, Datsopoulos, S & Hollis, C (2006). Enhanced cognitive control in young people with Tourette’s syndrome. Current Biology, 16(6), 570-573.
  3.  Felling, R & Singer, H (2011). Neurobiology of Tourette syndrome: current status and need for further investigation. Journal of Neuroscience, 31(35), 12387-12395.  https://www.barnesandnoble.com/w/advances-in-the-neurochemistry-and-neuropharmacology-of-tourette-syndrome-elsevier-science/1116107584?ean=9780124115613
  4.  Worbe, Y, Malherbe, C, Hartmann, A, Pélégrini-Issac, M, Messé, A, Vidailhet, M & Benali, H. (2012). Functional immaturity of cortico-basal ganglia networks in Gilles de la Tourette syndrome. Brain, 135(6), 1937-1946.
  5.  Bäumer, T, Thomalla, G, Kroeger, J, Jonas, M, Gerloff, C, Hummel, F & Münchau, A. (2010). Interhemispheric motor networks are abnormal in patients with Gilles de la Tourette syndrome. Movement Disorders, 25(16), 2828-2837.
  6.  The Centers for Disease Control and Prevention. Tourette Syndrome (TS). Retrieved from https://www.cdc.gov/ncbddd/tourette/data.html.
  7.  Roessner, V, Plessen, K, Rothenberger, A, Ludolph, A, Rizzo, R, Skov, L & ESSTS Guidelines Group. (2011). European clinical guidelines for Tourette syndrome and other tic disorders. Part II: pharmacological treatment. European child & adolescent psychiatry, 20(4), 173-196.
  8.  Verdellen, C, Van De Griendt, J, Hartmann, A, Murphy, T & ESSTS Guidelines Group (2011). European clinical guidelines for Tourette syndrome and other tic disorders. Part III: behavioural and psychosocial interventions. European child & adolescent psychiatry, 20(4), 197-207.
  9.  Müller-Vahl, K, Cath, D, Cavanna, A, Dehning, S, Porta, M, Robertson, M & ESSTS Guidelines Group. (2011). European clinical guidelines for Tourette syndrome and other tic disorders. Part IV: deep brain stimulation. European child & adolescent psychiatry, 20(4), 209-217.

Tourette Syndrome Brain Clinic