The cytokine profile of OCD: pathophysiological insights

Obsessive-compulsive disorder (OCD) is a psychiatric condition characterized by the presence of obsessions and/or compulsions, which has been commonly associated with alterations of some neurotransmitters systems, in particular, the serotonin and dopamine ones. However, it is now evident that these supposed disturbances cannot explain the development of this disorder, and so other possible mechanisms have been invoked, such as those involving the immune system that is attracting an increasing interest. According to the current literature, immune system alterations are reported in OCD of both children and adults. In children, it has been widely described as a clinical syndrome resulting from infections driven by group A [beta]-hemolytic streptococci and characterized by rheumatic fever, OCD, and neurological symptoms called "pediatric autoimmune neuropsychiatric disorders associated with streptococcus". In adults, available findings are meager and controversial, although intriguing. Such preliminary findings underline the presence of OCD in a number of autoimmune disorders, as well as of alterations of different immune parameters in OCD patients. This paper aims at presenting an exhaustive review of the role of the immune system in the development of OCD, with a major focus on the possible pathophysiological role of cytokines that seems to open novel treatment options. Keywords: OCD, cytokines, immune system, inflammation, PANDAS