A demographic change towards an increasing proportion of old and oldest old in industrialised societies is well known. The past decades’ declining birth rates and improved survival among older people are among the major driving forces.
An important aspect is to determine the overall health profile of the current population of long-lived individuals. In this way, we more accurately can forecast the societal challenges.
Adding years to life
Therefore it is crucial to disentangle whether the oldest old are more frail and disabled, or if they have improved in overall functioning compared to previous cohorts. There are two conflicting hypotheses: “The Failures of Success” hypothesis states that a cohort with an increasing proportion of individuals surviving to very old age will also show higher mean levels of disability and disease at a given old age, thus challenging the welfare of societies.
However “the Success of Success” hypothesis states that exceptionally long living individuals are expected to have higher level of functional capacity.
The latter is supported by a Danish epidemiological study of the 1905 and 1915 cohorts, published in Lancet 2013. Here we found that in the most recent birth cohort more individuals were living into their nineties with better overall functioning.