 The study is a cross sectional study. We recruited 40 cognitive impairment patients from the memory clinic at National Taiwan University Hospital and another 20 healthy controls matched for age and gender. We collected the actigram and physical activity from questionnaire for 7 days and performed the analysis for reliability and validity. We will do correlation analysis with the data with resting state functional MRI and tractography, brain connectivity, and plasma Aβ1-40 and Aβ1-42 amyloid protein. 