<qa>  What is the exclusion criteria for participants who develop more severe cognitive problems?The criteria below pertain only to the Screening and Baseline Visits, except where otherwise noted. If any of the conditions develop while the participant is in the study, the participant remains in the study. In particular, participants who develop cognitive and motor problems from medical conditions such as stroke or Parkinson s disease are retained in the study, although they are excluded from specific testing in which their underlying health condition is an exclusion criterion. Participants that develop more severe cognitive problems and are diagnosed with dementia, will no longer be able to participate in the study. 