Progress in medicine is painfully slow, in part thanks to the perverse incentives that drag down every heavily regulated field. But seven decades are left before we reach the closing years of this century. Seventy years in medicine is a long time. Consider what the medical science of the 1950s looked like in practice; consider what the treatment options looked like for common age-related diseases in that era, where they existed at all. Given that a longevity industry is just getting started, barely a decade old at this point, it seems a strange idea to bet against sizable gains in human life span before the end of the century. Even we play it safe and suggest that it will take a good 20 years or more to measure the degree to which novel forms of therapy extend healthy life in human patients, that still leaves a good long time for the research and development of rejuvenation therapies aimed at the repair of forms of molecular damage that cause aging.
Still, one can't argue against the diminishing returns produced by the old way of doing things when it comes to treatment and prevention of age-related disease. That encompasses public health measures aimed at reducing smoking (and now obesity, the largest problem of our era, as smoking was the largest problem of a past one), improved wealth, and the introduction of therapies that can modestly slow or reduce some of the consequences of aging without actually addressing its causes. Medicine that reduces blood pressure or lowers LDL-cholesterol, for example. Both are influential in the populations that use it, when considered from an epidemiological viewpoint where a 10-20% risk reduction is sizable across a population. But for an individual, a 10-20% risk reduction isn't all that great. It certainly isn't rejuvenation. But that is what the old approach to age-related disease gave us, marginal therapies, marginal outcomes.
The reason that betting against radical life extension seems foolish is that there are now earnest efforts underway to treat aging as a medical condition, a whole new approach to the problem of age-related disease. None of this has yet to reach the clinic in any widespread way, so who knows how effective the initial therapies will turn out to be. On balance, and over the course of decades, one would have to think that a biotech industry actively trying to slow and reverse aging by addressing its causes will make significantly greater progress towards longer healthy lives than a medical industry that was only trying to treat the symptoms of aging.
Implausibility of radical life extension in humans in the twenty-first century
More than three decades have passed since predictions were made about the upper limits to human longevity. Evidence presented here based on observed mortality trends in the worldʼs eight longest-lived populations and in Hong Kong and the United States, and metrics of life table entropy, indicate that it has become progressively more difficult to increase life expectancy. At ages 65 and older, the observed average rate of improvement in old-age mortality in the longest-lived populations evaluated here was 30.2% from 1990 to 2019. The impact of this level of mortality improvement, if experienced again over the next three decades, would yield only a 2.5-year increase in life expectancy at birth. This is a fraction of the 3-year per decade (for example, 8.7-year increase from 1990 to 2019) gain in life expectancy predicted by those claiming that radical life extension was forthcoming or already here. That is, old-age mortality has not been declining since 1990 at a pace that is even close to the rate of improvement required to achieve radical life extension in this century.
Where uncertainty remains is how much more survival time can be manufactured with the disease model that now prevails (shown here to have a declining influence on life expectancy) and the far greater uncertainty associated with future improvements in survival that may result from the deployment of gerotherapeutics or other advances in medicine that cannot be conceived of today. Because radical lifespan extension brought forth by yet-to-be-developed medical advances cannot be empirically evaluated over short timeframes, a limitation here (and within the field of aging in general) is that it is difficult to justify any numerical estimate of their future influence on life expectancy.
Forecasts about radical life extension in humans thought to be occurring now or projected to do so in the near term have already influenced the operations and financial structure of multiple industries. Results presented here indicate that there is no evidence to support the suggestion that most newborns today will live to age 100 because this would first require accelerated reductions in death rates at older ages (the exact opposite of the deceleration that has occurred in the last three decades). Furthermore, even if the 30.2% improvements in mortality in the 65-and-older population observed to have occurred in high-income nations from 1990 to 2019 occurred again, only a small fractional increase in survival to age 100 would ensue.
The evidence presented here indicates that the era of rapid increases in human life expectancy due to the first longevity revolution has ended. Given rapid advances now occurring in geroscience, there is reason to be optimistic that a second longevity revolution is approaching in the form of modern efforts to slow biological aging, offering humanity a second chance at altering the course of human survival. However, until it becomes possible to modulate the biological rate of aging and fundamentally alter the primary factors that drive human health and longevity, radical life extension in already long-lived national populations remains implausible in this century.
View the full article at FightAging
