 Lewy body spectrum disorders are a common group of neurodegenerative diseases that cause memory loss, behavioural and motor disabilities that impair quality of life. Cognitive enhancers help people afflicted with these conditions. However, some people do not benefit from this treatment, while others experience serious side effects. Side effects and poor response lead to hospitalization and early institutionalization. Pharmacogenomics, the study of how DNA variation can influence drug effects, will be combined with functional changes in brain imaging in response to cognitive enhancers in patients with Lewy body disease. The goal is to develop a predictive test that can be administered in the clinic to aid physicians choice of initial medication. This can reduce health care costs and improve treatment to Canadians suffering from these devastating disorders. 