Determining Sex Differences in Tourette's Syndrome and OCD
Paul Lombroso, M.D.,Professor, Child Study Center
Tourette’s Syndrome (TS) and Obsessive Compulsive Disorder (OCD) cause significant functional impairment and emotional distress, and are genetically related disorders in some families. In these families, Tourette’s Syndrome is more common in males, while OCD is more common in females. The appearance of these genetic disorders in different forms by gender is among the least understood aspects of these disorders. Dr. Lombroso explored the development of these disorders and associated sex differences focusing on an autoimmune hypothesis that certain bacterial and viral illnesses in childhood may be the possible cause for some cases of TS and OCD.
Highlighted Study Findings
Previously, an animal model of autoimmune factors related to occurrence of both Tourette’s Syndrome (TS) and Obsessive-Compulsive Disorder (OCD) was successfully developed. However, this model did not account for the sex difference in TS and OCD prevalence seen in humans. This new study explored the development of these disorders and associated sex differences using a newly developed animal model using an autoimmune hypothesis (in which the body generates an anti-infection response against its own cells) as a possible cause for some cases of TS and OCD. Specifically, the research tested the hypothesis that exposure to certain bacterial and viral illnesses in childhood invoke an immune response that produces substances in the blood (i.e. antibodies) to fight the infection. However, the antibodies that are produced also recognize the body's brain proteins and compromise their normal activity (thus, they become known as autoantibodies). The results of this study indicated that certain TS and OCD patients did have higher autoantibodies than those in the control groups, however this could not be determined by sex. However, the researchers were able to show that placing small amounts of these autoantibodies into specific brain regions of rats produces repetitive movements, called stereotypies, thus allowing for the development of a valid animal model of tics.