The participants (N = 1671) were part of the Baltimore Longitudinal Study of Aging (BLSA), a prospective cohort study of physical and psychological aging.18 At entry, participants are generally in good health; extensive exclusion criteria (see ClinicalTrials.gov Identifier: NCT00233272) ensure that participants have no physical or cognitive impairments when they enter the study. Although they remain a relatively healthy group, participants develop diseases and disabilities as they age. For example, the incidence of metabolic syndrome in the BLSA is in line with data from similar samples 19 and BLSA participants tend to have similar levels of depressive symptoms to other cohorts.20 The incidence of AD in this sample is also consistent with the rate found in other studies.21
