The old are not as physically aged as they used to be. Today's old people are in better shape than their predecessors, with access to better medicine and having been exposed to a lesser burden of infectious disease and other causes of cell and tissue damage over the course of a lifetime. Given the pace of progress in medical science these improvements can be seen even over the course of the past few decades. Many of today's researchers look at this and see compression of morbidity, a popular viewpoint in which it is believed that healthy life span can be extended considerably without extending overall life span. This doesn't make a great deal of sense from the viewpoint of aging as a consequence of accumulated biological damage, however. In the damage perspective the risk of death and level of dysfunction and frailty are determined by the present levels of various forms of damage. Reducing the pace at which the damage load increases extends both overall life span and time spent in decline; you can't have one without the other. Making an immediate reduction in damage, such as through some form of rejuvenation treatment, will extend healthy life span and postpone the future decline, but absent further treatments that decline would look exactly the same when it does arrive.
The only way in which you might see something that looks like compression of morbidity is if the pace of accumulation for most forms of damage are slowed, but not for one or more late-onset types of damage that produce reliably fatal consequences. This may or may not be what has happened over the past fifty years or so; there is a lot of room for argument given the present state of data. One intriguing line of thought relates to senile systemic amyloidosis, which seems to be the cause of death for most supercentenarians. It isn't much seen in less aged individuals, and there is comparatively little known of its progression in old age.
Still, the old are getting younger. Not fast enough yet, but step by step as a side-effect of improvements across the board in health, wealth, and medical science. The goal for the future is to step away from this incidental improvement in favor of strategies that deliberately target the causes of aging for treatment and repair. The coming age of medicine will prove to be far more effective in extending healthy life: there is a great deal of difference between trying and not trying to achieve a given goal.
Looking at two stages of the Berlin Aging Study, the first carried out between 1990 and 1993 and the second between 2013 and 2014, the team made some large-scale assessments of how old-age vitality has changed, along with some speculations as to why. Overall, despite growing obesity concerns and a stagnant international smoking rate, people seem to be aging more gracefully. Past the advances that have kept people in better physical shape, cognitive tests showed 75-year-olds today were an average of 19.6 years "younger" relative to 75-year-olds in the early 1990s. That is, people tested at 75 today performed as well as a 55-year-old would have two decades ago. "This is, by any means, a huge effect."
On average, today's 75-year-olds are cognitively much fitter than the 75-year-olds of 20 years ago. At the same time, the current generation of 75-year-olds also reports higher levels of well-being and greater life satisfaction. "The gains in cognitive functioning and well-being that we have measured here in Berlin are considerable and of great significance for life quality in old age." The researchers relate the gains to sociocultural factors such as education. In their opinion, the increase in well-being is also due to better physical fitness and higher levels of independence in old age. "However, we expect that these positive historical trends are attenuated at the end of life." During the final stage of life, the increase in good years of life is likely to give way to a rapid and marked drop in both cognition and well-being.
We compared data obtained 20 years apart in the Berlin Aging Study (BASE, in 1990-93) and the Berlin Aging Study II (BASE-II, in 2013-14). Relative to the earlier-born BASE cohort, the later-born BASE-II cohort showed better cognitive performance and reported higher well-being, presumably due to culture-based advances in the course of the past century. Our results suggest that historical trends favoring later-born cohorts in cognitive performance carry into old age, constitute strong effects at age 75 years, and generalize to multiple key indicators of perceived quality of life. The cognitive performance of BASE-II participants was on average 19.61 years "younger" relative to the BASE cohort.