APOE and Cognitive impairment: We divided each sample into six groups based on the number of copies of APOE-e4 (none, one, and two, i.e., APOE-e4/e4) and age (60–64, 65–69, and 70–75 years), and developed estimates of the risk of developing mild cognitive impairment or dementia in each group during the five years planned for the trial as well as “lifetime” risk through age 80–85 years.