Advanced age is the main risk factor for most chronic diseases and functional deficits in humans, but the fundamental mechanisms that drive ageing remain largely unknown, impeding the development of interventions that might delay or prevent age-related disorders and maximize healthy lifespan.The key phrase here is "healthy lifespan." This is not the same as increasing lifespan, but only making the older years healthier than they would otherwise have been. The experiments on mice that led to the conclusion that this is possible are complex, and we are almost certainly a long way from having any application to humans, but as the Economist concludes:
Genetically engineering people in the way that Dr Baker engineered his mice is obviously out of the question for the foreseeable future. But if some other means of clearing cells rich in P16INK4A from the body could be found, it might have the desired effect. The wasting and weakening of the tissues that accompanies senescence would be a thing of the past, and old age could then truly become ripe.