The Sydney Centenarian Study: methodology and profile of centenarians and near-centenarians

Background: The study of exceptionally long-living individuals can inform us about the determinants of successful aging. There are few population-based studies of centenarians and near-centenarians internationally, but none in Australia. Methods: Individuals 95 years and older were recruited from seven electoral districts in Sydney using the electoral roll, Medicare lists, and multiple other strategies to obtain a representative sample. Physical and mental health and cognitive status were assessed using standard instruments in multiple sessions, with assessments individually adapted. An informant was interviewed, and participants were invited to donate a blood sample, undergo an MRI scan, and enrol into the brain donation program. Results: Preliminary data on the first 200 participants are reported. Mean age was 97.4 years (range 95-106), with 29.5% being men, and 58.5% living in a private dwelling. Rates of heart disease and diabetes were lower than in octogenarians, but hearing and visual deficits were common. The mean mini-mental state examination (MMSE) score was 21.1, with men performing better. Rates of psychological distress were low and satisfaction with life high (mean 5.91 out of a maximum of 7); 54% scored <24 on MMSE; 39.5% were impaired on both MMSE and a functional measure; and 20% had previous diagnosis of dementia. Conclusions: This is a preliminary report describing the methodology of the study. It provides further evidence that dementia is not inevitable at this age and independent living is common. The study provides an excellent resource to determine the genetic and environmental contributions to long and successful cognitive aging.