[1] Inst Nacl Ciencias Med & Nutr Salvador Zubiran, Dept Geriatria, Geriatria Neurol, Mexico City, DF, Mexico
[2] Inst Ciencias Med & Nutr Salvador Zubiran, Dept Geriatria, Mexico City, DF, Mexico
[3] Inst Nacl Ciencias Med & Nutr Salvador Zubiran, Dept Neurol & Psiquiatria, Mexico City, DF, Mexico
[4] Harvard Med Sch, Massachusetts Gen Hosp, Dept Neurol & Psychiat, Boston, MA USA