What makes you tic? Translational approaches to study the role of stress and contextual triggers in Tourette syndrome

Abstract

Tourette syndrome (TS) is a neurodevelopmental condition characterized by multiple, recurring motor and phonic tics. Rich empirical evidence shows that the severity of tics and associated manifestations is increased by several stressors and contextual triggers; however, the neurobiological mechanisms responsible for symptom exacerbation in TS remain poorly understood. This conceptual gap partially reflects the high phenotypic variability in tics, as well as the existing difficulties in operationalizing and standardizing stress and its effects in a clinical setting. Animal models of TS may be highly informative tools to overcome some of these limitations; these experimental preparations have already provided critical insights on key aspects of TS pathophysiology, and may prove useful to identify the neurochemical alterations induced by different stressful contingencies. In particular, emerging knowledge on the role of contextual triggers in animal models of TS may inform the development of novel pharmacological interventions to reduce tic fluctuations in this disorder.

Keywords: Animal models; Premonitory sensory phenomena; Stress; Tics; Tourette syndrome.

Figure 1. Synoptic diagram of the hypothesized link between premonitory sensory phenomena and tics

Stressors and contextual triggers increase the intensity of premonitory sensory phenomena and dopaminergic activity, ultimately leading to tic exacerbation. In turn, tic execution mitigates the intensity of premonitory sensory phenomena; this hypothetical coping process may potentially result in the formation of a maladaptive habit. See text for details.