[1] Brigham & Womens Hosp, Channing Lab, Dept Med, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Boston, MA 02115 USA
[3] Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA
[4] Harvard Univ, Sch Publ Hlth, Dept Epidemiol, Boston, MA 02115 USA
[5] NIEHS, Epidemiol Branch, Res Triangle Pk, NC 27709 USA
[6] Massachusetts Gen Hosp, Dept Neurol, Boston, MA 02114 USA