Can we spot deleterious ageing in two waves of data? The Lothian Birth Cohort 1936 from ages 70 to 73

Abstract

'Younger' old age (the late 60s through early 70s) is, for many, a period of stability of lifestyle and considerable freedom to pursue leisure activities. Despite the stability that many enjoy, the mortality rate is about 2% per year in western nations. This increases to about 5% by age 80. It would be useful to know if those most vulnerable can be identified through patterns of deleterious ageing, and especially if this could be accomplished with just two waves of data. The Lothian Birth Cohort 1936 was surveyed on a host of individual difference variables including cognition, personality, biomarkers of physical health, and activities at ages 70 and 73 years. Overall, the group showed the expected basic stability in mean levels for these variables, but some individuals had died and others did show substantial changes that could be considered statistically reliable. These presumably reliable changes were at least as likely to be positive (reflecting improved condition/ability) as negative (reflecting decline/ageing). Moreover, limitations in the estimated reliabilities of the measures meant that most of the observed changes could not be considered reliable. The changes clustered only weakly around general health to predict death over the next approximately two years. We concluded that two waves of longitudinal data were not sufficient to assess meaningful patterns of ageing, despite often being used to do so.