It is believed that the symptoms of Tourette Syndrome (TS) and a range of other neuropsychiatric syndromes including obsessive-compulsive disorder (OCD) may begin after a bacterial (streptococcal) throat infection. Blood samples taken from children with TS and/or OCD attending specialist clinics indicate that 30% to 40% of them had previously been infected by Streptococcus. However, it is unknown how common such an association is in the general community, and there remains controversy regarding the relationship of streptococcal infection and TS/OCD symptoms. Therefore we are doing an epidemiological study to establish whether or not there is a link between streptococcal infection and neuropsychiatric disorders in the community. We will analyze data from a large primary care database for an association between throat infection, with and without confirmation of streptococcal infection, and the first occurrence of TS or OCD. The data from each person with TS or OCD will be compared with data from ten other people who do not have TS or OCD but who are of similar age and sex and from the same primary care practice. Sub-group analyses will determine whether more people with TS or OCD have proven streptococcal infections compared to non-specific bacterial throat infections and those treated with antibiotics. We will also undertake analyses to determine whether gender, age group and socioeconomic status have any influence on the results. An association of streptococcal infection would make streptococcal infection a risk factor for the development of TS/OCD, and provide a better understanding in the etiology, pathogenesis, prevention and treatment of these disorders. This study will supplement ongoing investigations into the role of streptococcal infection in the development of TS. It is very relevant to TS as it is investigating a potential cause of the syndrome. Anette Schrag, M.D., Ph.D., University College Medical School, London, United Kingdom Mary M. Robertson, M.D., University Hospital, London, United Kingdom Gavin Giovannoni, Ph.D., University Hospital, London, United Kingdom Yoav Ben-Shlomo, Ph.D., University College Medical School, London, United Kingdom Chris Metcalfe, Ph.D., Cambridge University, Cambridge, United Kingdom Award: $69,815 This study is supported by a generous donation from Sam & Shirley Zemsky Tourette Association of America Inc. – Research Grant Award 2006-2007