Increased serum levels of interleukin-12 and tumor necrosis factor-alpha in Tourette's syndrome

Background: The hypothesis that common infections can modulate the onset and course of tic disorders and early-onset obsessive-compulsive disorder (OCD) in pediatric populations is longstanding. To date, most investigations have focused on the hypothesis of molecular mimicry and humoral immune responses. This study was carried out to investigate whether cytokines associated with the innate immune response or T cell activation were altered under baseline conditions and during periods of symptom exacerbation. Methods: Forty-six patients with Tourette's syndrome and/or early-onset OCD, aged 7-17 years, and 31 age-matched control subjects participated in a prospective longitudinal study. Ratings of clinical severity and serum were collected at regular intervals, and serum concentrations of 10 cytokines were measured repeatedly. Results: Interleukin-12 and tumor necrosis factor α concentrations at baseline were elevated in patients compared with control subjects. Both of these markers were further increased during periods of symptom exacerbation. Conclusions: These findings suggest that symptom exacerbations are associated with an inflammatory process propagated by systemic and local cytokine synthesis that might involve the central nervous system. We conclude that, in the future, longitudinal studies of children with neuropsychiatric disorders should examine the involvement of innate and T cell immunity.