Inclusion Criteria:  All consecutive citizens in the CUHK Brain Health Longitudinal Study cohort who received baseline MRI brain.  Exclusion Criteria:  Citizens with clinically evident stroke or dementia prior to recruitment; or Citizens who are unable to provide an informed consent; or Citizen with contraindications to MRI brain, e.g., non-MRI compatible implants, claustrophobia, etc; or Citizens who had no baseline MRI brain assessment.