Tic disorders and obsessive-compulsive disorder: is autoimmunity involved?

The precise cause of tic disorders and paediatric obsessive-compulsive disorder (OCD) is unknown. In addition to genetic factors, autoimmunity may play a role, possibly as a sequela of preceding streptococcal throat infections in susceptible children. Here we review the most recent findings, from July 2003 onwards, with regard to a possible relationship between tics/OCD and autoimmunity. Evidence about an intriguing correlation between streptococcal infections and tic disorders and OCD is accumulating. Specific criteria have been outlined for paediatric autoimmune disorders associated with streptococcal infections (PANDAS), but autoimmunity may also be involved in tic disorders and/or OCD in general. Anti-basal ganglia auto-antibodies are an important potential indicator of autoimmunity. Although the lack of a standardized methodology makes comparisons of findings difficult, new data has emerged pointing to the possible involvement of specific auto-antigens. Earlier findings of increased D8/17 B cell expression as a putative susceptibility marker could not be replicated, possibly due to instability of the D8/17-binding antibody. Although PANDAS patients have been reported to improve after therapeutic plasma exchange, and antibiotics may prevent symptom exacerbations, immune-based treatments should not be routinely given. In future studies, demonstrating the pathogenetic significance of anti-basal ganglia antibodies in animals is a major challenge to draw any firm conclusions about a role for autoimmunity. Future longitudinal studies should be aimed at assessing the precise relationship between symptom exacerbations, infections, and immune parameters, possibly along with gene expression profiles.