De-ageing treatments are medical procedures intended to reverse, stall, or oppose the ageing process. While highly complex and often extremely expensive, de-ageing, or ‘rejuvenation’ therapies are relatively common throughout known space, though their availability within a population or civilisation is highly contingent on culture and economic prosperity.
Efficacy
The efficacy of de-ageing treatments varies wildly according to the exact procedure and circumstances. In general, the most bleeding edge medicine is enormously effective, able to stave off the ageing process indefinitely, albeit that treatment cycles become more frequent and more harrowing the longer one lives.
The biggest issue with the therapies is that they are enormously unpleasant to endure, involving significant physical suffering and in some cases lasting up to six months. While the ageing process can be slowed in fairly pain-free ways, turning back time often carries a significant cost. So awful is the experience that many often only subject themselves to one or two cycles before deciding it simply is not worth the torment to further prolong their natural lifespans.
While research is investigating how to reduce the unpleasantness of rejuvenation therapies, for many more cold and calculating thinkers it is a useful limitation that prevents civilisations from having to answer a number of rather complicated questions.
Distribution
De-ageing therapies are commonplace in the first-rate powers. For example, the Reunification Alliance offers various procedures to all of its citizens for only a nominal fee of work-credits. The idea behind this is that one must contribute some form of labour to be eligible for rejuvenation therapies, but even a limited amount of part-time work is usually enough to fund a full treatment cycle.
Only the Illuminators make de-ageing therapy even more common, with it being freely available to all members of their population.
Meanwhile, both the Celestian Empire and the Kharak-Ghar Republic of Militant Citizens impose much stricter limitations on who has access to rejuvenation, despite both powers having the wealth to make it fairly widely available. In both cases, access to therapies must be earned through significant achievement, or else paid for at enormous personal expense. Notably the Kharak-Ghar do offer one round of therapy for everyone who earns citizenship (obtained through military service), with more cycles available for war heroes, religious figures, or prominent officers. In the Celestian Empire it is almost purely an economic question, available to those willing and able to stump up the cash.
In smaller civilisations, meanwhile, access to de-ageing treatment is naturally and necessarily more limited, with the exact nature of this varying wildly. There are plenty of planets so poor that it is simply unheard of, and others where only the super-rich stand any chance of obtaining access.
On High Atlantic, rejuvenation therapies are enormously expensive but not totally unattainable. This is partially because the Tourist Board has hoped to get in with the medical tourism injury, and partially because it is ultimately a very wealthy, and hence technologically advanced, planet. There are few restrictions beyond the economic, and various prominent mercenaries have managed to extend their career through various therapies - those who last long enough, anyway.