Aging is accumulated cell and tissue damage, and the slow growth of healthy human life expectancy that has taken place over the past two centuries thus reflects a lesser load of a damage present in individuals of a given age. The old in their 60s and 70s today are on average less damaged and less frail than people of the same chronological age were in the past. This trend is incidental, however, an unintended side-effect of broad improvements in medicine and related technologies that have other immediate goals: control of infectious disease, treatment of specific age-related conditions, and so forth. Things will change in the near future as the focus slowly turns to deliberate efforts to treat aging as a medical condition, as this should produce much faster gains in healthy human life span.
Faster increases in life expectancy do not necessarily produce faster population aging, according to new research. This counterintuitive finding was the result of applying new measures of aging to future population projections for Europe up to the year 2050. "Age can be measured as the time already lived or it can be adjusted taking into account the time left to live. If you don't consider people old just because they reached age 65 but instead take into account how long they have left to live, then the faster the increase in life expectancy, the less aging is actually going on."
Traditional measures of age simply categorize people as "old" at a specific age, often 65. But previous research has shown that the traditional definition puts many people in the category of "old" who have characteristics of much younger people. "What we think of as old has changed over time, and it will need to continue changing in the future as people live longer, healthier lives. Someone who is 60 years old today, I would argue is middle aged. 200 years ago, a 60-year-old would be a very old person. The onset of old age is important because it is often used as an indicator of increased disability and dependence, and decreased labor force participation. Adjusting what we consider to be the onset of old age when we study different countries and time periods is crucial both for the scientific understanding of population aging for the formulation of policies consistent with our current demographic situation."
In the new study the researchers compared the proportion of the population that was categorized as "old" using the conventional measure that assumes that people become "old" at age 65 and the proportion based on their new measure of age, which incorporates changes in life expectancy. The study looked at three scenarios for future population aging in Europe, using three different rates of increase for life expectancy, from no increase to an increase of about 1.4 years per decade. The results show that, as expected, faster increase in life expectancy lead to faster population aging when people are categorized as "old" at age 65 regardless of time or place, but, surprisingly, that they lead to slower population aging when the new measures of age are used.