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A new study by researchers at Columbia University Mailman School of Public Health's Center for Infection and Immunity indicates that pediatric obsessive-compulsive disorder (OCD), Tourette syndrome and/or tic disorder may develop from an inappropriate immune response to the bacteria causing common throat infections. The mouse model findings, published in Molecular Psychiatry, support the view that this condition is a distinct disorder, and represent a key advance in tracing the path leading from an ordinary infection in childhood to the surfacing of a psychiatric syndrome. More than 25% of adults and over 3% of children manifest some features of OCD and tic disorders. Until now, scientists have been unable to convincingly document the association between the appearance of antibodies directed against Group A beta-hemolytic streptoccoccus (GABHS) in peripheral blood and the onset of the behavioral and motor aspects of the disorder. As a result, treatment strategies were restricted to targeting symptoms rather than causes. Strep throat bacteria, or GABHS, are known to cause autoimmune disorders such as Sydenham chorea, with symptoms such as fever and uncontrolled tics of the face or extremities in susceptible individuals, prompting some scientists to suspect that GABHS could play a role in a syndrome known as Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS), a rapid-onset and episodic form of OCD and tic disorders observed in some children. The latest study by CII researchers supports the hypothesis that some neuropsychiatric syndromes may be triggered by direct action of GABHS-associated antibodies on the brain. Whether environmental factors other than GABHS can lead to similar effects is as yet unknown. Using a mouse model of PANDAS, Mady Hornig, MD, associate professor of epidemiology at Columbia University Mailman School of Public Health, and colleagues demonstrate this suspected link between GABHS antibodies and the psychiatric symptoms of the disorder. Immunising mice with an inactivated form of the bacteria, CII researchers found that the mice exhibited repetitive behaviours reminiscent of children with PANDAS. Injection of antibodies from the immunised mice into the bloodstream of non-immunized mice replicated these behaviours.
More research on obsessive compulsive behaviour First Published in September 2009
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