Data were included from individuals participating in a prospective study of 2,126 Medicare recipients, 65 years and older, residing in a single community in Northern Man- hattan. Each person received the same medical, neurological and neuropsychological evaluations at regular intervals. The cohort was followed over a 7-year period beginning in 1992. Three follow-up examinations took place at 20-month in- tervals after the baseline interview. Over the study period, the annual mortality rate has been , the overall refusal rate has been 10% and the annual incidence rate of AD has been 3% [63]. In order to address the study hypothesis, we included data only from 563 individuals without dementia (AD or other forms),.
