Neuroimmunology of tics and Gilles de la Tourette Syndrome

In the past decades, the connection between the immune system and Tourette syndrome (TS) has been explored as a potential pathophysiologic key aspect. This idea is supported by studies describing the effect of immune cells and inflammatory mediators in neurodevelopment by acting in synaptic arrangement, pruning, and maturation of neural circuitries. Supporting evidence for that correlation is varied, including genome-wide association studies, transcriptome analysis, animal models, and clinical populational-based studies. Moreover, the influence of environmental aspects typically involved in immunologic response and the association of TS with allergies and autoimmune diseases adds to the immune-based neurodevelopment theory. Overall, the research data looking at this association points toward a proinflammatory state, even though there is still uncertainty about the exact role and implication of this immunologic profile in TS, especially due to the lack of robust evidence regarding immunomodulatory treatments. Furthermore, the discrepancy of results in studies shed doubt on the immunologic hypothesis. In this chapter, we summarize the scientific knowledge regarding immunology in TS, discussing it from a historical perspective to more recent studies.