[1] Harvard Med Sch, Boston, MA 02115 USA
[2] Massachusetts Gen Hosp, Dept Neurol, Boston, MA 02114 USA
[3] Brigham & Womens Hosp, Dept Neurol, 75 Francis St, Boston, MA 02115 USA
[4] Natl Inst Drug Abuse, Baltimore, MD 21224 USA
[5] Johns Hopkins Med, Dept Psychiat, Baltimore, MD 21205 USA