1 Department of Medicine, University of California San Francisco, San Francisco, California, USA.
2 Department of Geriatrics and Gerontology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
3 Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan City, Taiwan.
4 Department of Psychiatry and Behavioral Sciences, University of California San Francisco, San Francisco, California, USA.
5 Department of Medicine, San Francisco VA Health Care System, San Francisco, California, USA.