While further studies facilitated by international multicenter collaborations are needed to better understand these relationships and underlying mechanisms, the true test of causality lies in interventional clinical trials. For example, a role for prostagalandin and thromboxane synthesis is suggested by efficacy of celecoxib as an adjuvant to fluvoxamine in OCD (Shalbafan et al. 2015), and other therapies that modulate mucosal immunity may also prove to be of benefit. Trials aimed at determining the effects of probiotic treatment in adults with OCD (NCT02334644) and of ibuprofen on functional magnetic resonance imaging activation patterns in the amygdala (NCT02507219) are currently ongoing.
