Deconstructing Tourette Syndrome

Have you heard of Tourette syndrome? It is considered a rare disease based on its prevalence in the population. However, studies at the international level indicate that the disorder is actually much more common than previously thought [1,2].

Given that , June 7, is European Tourette Syndrome Awareness Day, today’s post is dedicated to debunking common myths and misconceptions about Tourette’s.

Let’s deconstruct Tourette syndrome.

WHAT IS TOURETTE SYNDROME?

According to international diagnostic criteria, Tourette syndrome (TS) is a primary motor disorder with the chronic presence of tics as a core feature [3,4], and is often associated with other conditions such as ADHD and OCD [1].

WHAT DEFINES A TIC?

The word tic derives from the Italian ticchio [5] meaning caprice as synonym of whim and extravagance [6,7]; however, far from being a whim or caprice of the individual who manifests them, tics are involuntary movements or vocalizations, although they may be extravagant because they appear repetitively with an inappropriate intensity and frequency, and are decontextualized or unrelated to situations since they are not goal-directed behaviors like voluntary movements [8] or the voluntary emission of words or sounds.

DECONSTRUCTING TOURETTE’S

• More than a syndrome, it is a spectrum disorder. Different subtypes of Tourette’s have been described [1,9], which is why it is currently considered more appropriate to speak of the spectrum of Tourette disorder rather than of Tourette syndrome [10].

• Blurting out obscenities is a rare symptom of Tourette’s. Coprolalia (inappropriate involuntary uttering of obscenities without offensive intent [1,10]) is one of the most popular symptoms of TS, partly due to its diffusion through cinema and media. Although coprolalia might certainly be one of the most significant features, it only occurs in less than one fifth of affected individuals [11].

• Special creativity for music. Although there is no linear relationship between excess of dopamine and creativity, the scientific literature emphasizes an association between Tourette’s disorder and musical creativity [12].

• Its origin is not psychological. The idea that the aetiology of Tourette syndrome was psychological has now been discredited [1] since aetiological suggestions include genetic factors and environmental influences [1].

A month ago, a study published in Neuron estimated that there are approximately 400 genes that contribute risk in 12% of clinical cases [13].

• Its pathophysiology is not limited to the basal ganglia. The anatomo-functional alterations involved in TS comprise multiple cortical and subcortical structures and not only the basal nuclei [14], which are associated with the automatization of voluntary behavior. Concerning tics, different cortico-striato-thalamo-cortical circuits are involved and are of four modalities: sensorimotor, orbitofrontal, limbic and associative loops [14], and may be altered at varying degrees in individuals with Tourette syndrome.

• Is much more common than previously thought. The European Commission on public health determines that rare diseases are conditions with prevalence below 0.05% [15], however, different studies suggest that the overall international prevalence of Tourette syndrome is 1% in the majority of cultures of the world 2],which is similar to the prevalence of schizophrenia.

BIBLIOGRAPHY

1. Robertson, M.M. (2012). The Gilles De LaTourette syndrome: the current status. Archives of Disease in Childhood: Education & Practice, 97(5), 166-175. http://dx.doi.org/10.1136/archdischild-2011-300585
2. Robertson, M.M., Eapen, V., &Cavanna, A. E. (2009). The international prevalence, epidemiology, and clinical phenomenology of Tourette syndrome: A cross-cultural perspective. Journal of Psychosomatic Research, 67(6), 475-483. http://dx.doi.org/10.1016/j.jpsychores.2009.07.010
3. American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders: DSM-5 (5th ed.) Washington D.C.: Author.
4. Organización Mundial de la Salud (1992) Clasificación Internacional de Enfermedades y Problemas Relacionados con la Salud: CIE-10 (10ª revisión). Ginebra: Autor.
5. Varsemanas, D. R. (septiembre de 2002). La incidenciadelestrés y losobjetivos de la terapiapsicológicaenlosaspectosbiopsicosociales y comportamentales del síndrome de Gilles de la Tourette. Unmodelointeractivo para la integración de factores. En S. Jurado (Presidencia). Primer Congreso Nacional de Síndrome de Tourette y TrastornosAsociados. ASTTA, Córdoba, España.
6. Accademia dellaCrusca(27May2017).http://www.accademiadellacrusca.it/it/link-utili/dizionari-sincronici
7. Dizionari Corriere (27May 2017)http://dizionari.corriere.it/dizionario_sinonimi_contrari/T/ticchio.shtml
8. Jankovic, J., &Fahn, S. (1986). The phenomenology of tics. Movement Disorders, 1(1), 17-26. http://dx.doi.org/10.1002/mds.870010103
9. Robertson, M.M. (2000). Tourette syndrome, associated conditions and the complexities of treatment. Brain, 123(3), 425-462. http://dx.doi.org/10.1093/brain/123.3.425
10. Robertson, M.M.&Eapen, V. (2013).Wither the relationship between aetiology and phenotype in Tourette In: Leckman JF, Martino, D (Eds.), Tourette Syndrome. Oxford University Press, New York, pp. 361–394.
11. Freeman, R.D., Zinner, S.H., Muller-Vahl, K.R., Fast, D.K., Burd, L.J., Kano, Y., Rothenberger, A., Roessner, V., Kerbeshian, J., Stern, J.S., Jankovic, J., Loughin, T., Janik, P., Shady, G., Robertson, M.M., Lang, A.E., Budman, C., Magor, A., Bruun, R., and Berlin, C.M. Jr. (2009) Coprophenomena in Tourettesyndrome.  Med. ChildNeurol,51: 218–227.DOI:10.1111/j.1469-8749.2008.03135.x
12. Espert, R., Gadea, M., Aliño, M. & Oltra-Cucarella, J. (2017). Neuropsicología del trastorno de Tourette: cognición, neuroimagen y creatividad. Revista de Neurología, 64 (s01): S65-S72. http://www.neurologia.com/articulo/2017015
13. Jeremy Willsey, Thomas V. Fernandez, DongmeiYu, Robert A. King, Andrea Dietrich, JinchuanXing, Stephan J. Sanders, Jeffrey D. Mandell, Alden Y. Huang, Petra Richer, Louw Smith, Shan Dong, Kaitlin E. Samocha, (2017). De NovoCodingVariants are StronglyAssociatedwithTouretteDisorder.Neuron, 94 (3), 486 – 499. DOI: http://dx.doi.org/10.1016/j.neuron.2017.04.024
14. Ganos, C., Roessner, V., &Münchau, A. (2013). The functional anatomy of Gilles de la Tourette Neuroscience &Biobehavioral Reviews, 37(6), 1050-1062.
15. Comisión Europea (27May2017). Las enfermedades raras: un desafío para Europa. http://ec.europa.eu/health/ph_threats/non_com/docs/raredis_comm_es.pdf
16. Ministerio de Economía, Industria y Competitividad e Instituto de Salud Carlos III (27 May 2017).Registro Nacional de Enfermedades Raras.https://registroraras.isciii.es/Comun/Inicio0.aspx
17. Instituto Nacional de Estadística (27 May 2017).http://www.ine.es/dyngs/INEbase/es/operacion.htm?c=Estadistica_C&cid=1254736176951&menu=ultiDatos&idp=1254735572981