1. San Francisco Veterans Affairs Health Care System , San Francisco, California , USA
2. Department of Psychiatry and Behavioral Sciences, University of California, San Francisco , San Francisco, California , USA
3. Northern California Institute for Research and Education , San Francisco, California , USA
4. Department of Epidemiology and Biostatistics, University of California, San Francisco , San Francisco, California , USA
5. Department of Neurology, University of California, San Francisco , San Francisco, California , USA