1. From the Department of Neurology, University of Southern California, Los Angeles (A.M.L., N.S., A.T.)
2. Department of Neurology, Mayo Clinic, Jacksonville, FL (M.P.L.)
3. Department of Biomathematics, University of California at Los Angeles (D.M.)
4. Department of Neurology, University of California, San Francisco (B.O.)
5. Los Angeles County Department of Health Services, CA (N.S., A.T.).