Prevalence of anti-basal ganglia antibodies in adultobsessive–compulsive disorder: cross-sectional study

BackgroundSymptoms of obsessive–compulsive disorder (OCD) have been described in neuropsychiatric syndromes associated with streptococcal infections. It is proposed that antibodies raised against streptococcal proteinscross-react with neuronal proteins (antigens) in the brain, particularly in the basal ganglia, which is a brain region implicated in OCD pathogenesis.AimsTo test the hypothesis that post-streptococcal autoimmunity, directedagainst neuronal antigens, may contribute to the pathogenesis of OCD inadults.MethodNinety-six participants with OCD were tested for the presence of anti-streptolysin-O titres (ASOT) and the presence of anti-basal ganglia antibodies (ABGA) in a cross-sectional study. The ABGA were tested forwith western blots using three recombinant antigens; aldolase C, enolase and pyruvate kinase. The findings were compared with those in a control group of individuals with depression (n = 33) and schizophrenia (n = 17).ResultsPositivity for ABGA was observed in 19/96 (19.8%) participants with OCDcompared with 2/50 (4%) of controls (Fisher's exact testP = 0.012). The majority of positive OCD sera (13/19)had antibodies against the enolase antigen. No clinical variables were associated with ABGA positivity. Positivity for ASOT was not associated with ABGA positivity nor found at an increased incidence in participants with OCD compared with controls.ConclusionsThese findings support the hypothesis that central nervous system autoimmunity may have an aetiological role in some adults with OCD. Further study is required to examine whether the antibodies concerned are pathogenic and whether exposure to streptococcal infection in vulnerable individuals is a risk factor for the development of OCD.