Recently Tourette's Syndrome has received a lot of attention in the media, thanks to TikTok. Many people have come up on the platform showcasing their symptoms. Billie Eilish, a popular pop singer, being one of them to reveal her condition to the public. But what are these tics and what causes them?
What is Tourette's Syndrome?
Tics are the primary symptom of Tourette's Syndrome or TS. It is a neurodevelopmental disorder classified under the Tic disorders in the DSM-5 classification. The patient experiences 'tics', that are sudden, involuntary and repetitive movements or sounds. It is important to understand that tics are impossible to control or stop.
These tics can be either vocal and/or motor. Further, these symptoms are classified into:
Simple Tics: Involves a few muscle groups and are more commonly occurring. For e.g., blinking, shrugging and sniffing etc.
Complex Tics: Includes coordinated movements of several muscle groups together. For e.g., jumping, twisting and repeating words or phrases etc.
These symptoms may appear or disappear and can change in time, frequency and severity, however, the condition is chronic. Certain situations or activities can trigger tics. Although there is no cure, the condition is manageable through proper treatment plan and lifestyle changes. Treatment for TS primarily involves medications and behaviour therapy.
What is the cause of Tourette's Syndrome?
As of now, the precise cause of TS is unknown and research is ongoing on the matter. But it has been found that genetics plays an important role. It is likely the consequence of various genes interacting together along with certain environmental factors that leads to an individual developing the disorder. There are several risk factors that are associated with the condition such as- smoking during pregnancy, pregnancy complications, low birth weight and infections. There are also a handful of comorbid conditions linked to TS such as- ADHD, OCD, anxiety, learning disabilities, sleep disturbances, behavioural and social issues.
It has proven challenging to pinpoint the exact risk alleles or gene abnormalities that cause the disorder. Research on the genetics of TS focusing on multiple generations has supported Mendelian inheritance pattern. The discovery of genetic alterations linked to the expression of TS supports the theory that the condition is inherited in an autosomal dominant manner, which means that if either of the parent is a carrier then the child has a 50% risk of developing the disorder.
Studies show multiple loci and several genetic mutations linked to TS, such as Slit and Trk-like 1 (SLITRK1) and histidine decarboxylase (HDC) genes along with the dopamine and serotonin system genes. Neurophysiological studies and brain imaging has shown a dopaminergic dysfunction. MRI studies have also determined a mild but consistent decrease in the basal ganglia region of patients affected with TS.
Even though, these findings highlight remarkable progress achieved in this field, there are still significant gaps present that need to addressed which provides potential areas for future research.
References
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental health disorders (5th ed.).
Centers for Disease Control and Prevention. (2023, May 31). Risk factors and causes for tourette syndrome. Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/tourette/riskfactors.html
Deng, H., Gao, K. & Jankovic, J. (2012). The genetics of Tourette syndrome. Nat Rev Neurol 8, 203–213. https://doi.org/10.1038/nrneurol.2012.26
Lin, W. D., Tsai, F. J., & Chou, I. C. (2022). Current understanding of the genetics of tourette syndrome. Biomedical journal, 45(2), 271–279. https://doi.org/10.1016/j.bj.2022.01.008
U.S. Department of Health and Human Services. (n.d.). Tourette syndrome. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/tourette-syndrome