Neurobiology of Tourette Syndrome

Tourette Syndrome (TS) is a neurodevelopmental disorder characterized by chronic motor and vocal tics. Although it is a common disorder in childhood, the etiology of Tourette Syndrome has not been fully elucidated yet. Studies, -conducted so far-have revealed differences in neurobiological structures of individuals who suffer from Tourette Syndrome. The objective of this review is to assess etiological and pathophysiological studies in the Tourette Syndrome literature. An electronical search was conducted in PubMed database using the keywords tic disorders, Tourette Syndrome, neurobiology, genetics, neuroimaging and animal models. Research and review studies published between 1985 and 2015, with a selection preference towards recent publications, were reviewed. According to the studies, genetic predisposition hypothesis is considered as a priority. However, a precise genetic disorder associated with Tourette Syndrome has not been found. The evidence from postmortem and neuroimaging studies in heterogenous patient groups and animal studies supports the pathological involvement of cortico-striato-thalamo-cortical (CSTC) circuits in Tourette Syndrome. Consequently, the most emphasized hypothesis in the pathophysiology is the dopaminergic dysfunction in these circuits. Furthermore, these findings of the animal, postmortem and neuroimaging studies have confirmed the neurodevelopmental hypothesis of Tourette Syndrome. In conclusion, more studies are needed to understand the etiology of the disorder. The data obtained from neurobiological studies of the disorder will not only shed light on the way of Tourette Syndrome, but also guide studies on its treatment options.