From the source [1]: "study participants 65 years or older were sampled randomly from Seattle-area GH members. Participants with dementia were excluded. The original cohort of 2581 participants was enrolled from 1994 through 1996. An additional 811 participants were enrolled from 2000 through 2003. In 2004, the study began continuous enrollment to replace those who died or dropped out."

[1] http://archinte.jamanetwork.com/article.aspx?articleid=20917...