Potential patients will be invited to a screening visit. This visit is designed to ensure that the patients meet study criteria and that it is safe for them to participate in the study. The screening visit will consist of physical examinations, medical and psychological history, cognitive and functional testing, interviews, questionnaires, research/clinical venipuncture, and a meeting with the study doctor. If a patient is accepted to the trial, he/she will be expected to stay in the study for a minimum of 6 months.