Read somewhere that there's a part of our chromosomes called telomeres. They are longer when we are young, but shorten as we age. Apparently this has a connection to the body aging. So unless any treatment can make those telomeres longer again, doubt any real body-wide anti-aging treatment would be effective.
Researchers have already found ways to prevent (and even reverse) telomere shortening in the laboratory. The trouble is that doing so is associated with tumor formation. For instance, in transgenic mice which don't experience telomere shortening, they don't even reach adulthood before dying of extensive tumors.
To think about cellular senescence from a survival standpoint, you really have to view it in terms of an evolutionary trade-off: on the one hand, it acts as a kind of emergency brake to terminate cells which are at risk of becoming cancerous, but on the other hand, it eventually accumulates to drive age-related pathology.
This was a paradoxical discovery for researchers, because it became apparent that the mechanisms which keep us alive when we're young are often the very same mechanisms which kill us when we're old. Even more paradoxically, while senescence acts as a major tumor suppressant during the early stages of life, it can actually be a major driver of tumor formation later in life (advanced biological age correlates strongly with higher incidences of cancer formation).
From the perspective of natural selection, I suppose this makes a kind of perverse sense. In the end, all evolution really cares about is our ability to survive long enough to successfully pass on our genes, and once we've done that, any extra time we have afterwards seems to serve little to no evolutionary purpose.
Whether researchers are able to come up with an intervention to get around this problem, at this point, remains to be seen, but it would be interesting to see how it could be done.
Have you ever heard the saying "You can't teach an old dog new tricks?". It's quite true, the way neural networks develop in the brain up until the mid-twenties enable young people to adapt and change their habits and ways of thinking wheras it's relatively rare older people can radically change their outlook or views in radical ways. Would womens sufferage have ever occurred in a world in which the men of the 18th century were still alive? Would serfs have ever gained liberty if the Black Death hadn't reduced the population so sufficiently that non-nobles could demand rights?
The consideration that people seem to become less open to new ideas with age is an interesting one, but can we really be sure that this is due to a person's age in the chronological sense, or due to a person's age in the biological sense?
On the one hand, I could see how, theoretically, an increasing number of experiences over the course of a person's life could lead to an increase and reinforcement of certain biases, but on the other hand, psychological research seems to suggest that while crystallized intelligence increases long after adulthood has been reached, fluid intelligence starts declining almost immediately after adolescence has ended.
Can we really say with confidence that the cantankerousness we witness in older people is due mostly to their experiences making them jaded, or could it have more to do with how their brains may have changed on a biochemical level? Speaking purely anecdotally, I have personally witnessed how dementia can cause formally jovial people to become increasingly withdrawn and irritable as the condition progresses. Couldn't the same be true of more subtle cognitive changes?
