At entry in the study, participants agreed to serial follow-ups with systematic physical and psychological examinations. The frequency of follow-up varied with age, with increasing frequency at older ages. Currently, participants 60 to 79 years old are tested every 2 years and participants 80 years old or older are tested approximately every year. Subjects included in the analyses were cognitively normal at time of the baseline personality assessment and had at least one follow-up evaluation. About 7% (n = 119) of participants in this study were lost to follow-up. Prior to each assessment, participants provided written informed consent. The protocol was approved by the local institutional review board.
