I’m passing this link on because it gives an explanation for the effects of ageing down to the mitochondrial and dna level. It’s a positive message that explains my faith that as I age I can keep my vitality. The findings need to be confirmed but they fit wider research. Just wanted to provide a reference so I don’t forget this. 
http://conditioningresearch.blogspot.com/2009/08/ageing.html

Mitochondria Are the Powerhouse of… Alzheimer’s?

Some researchers think mitochondria could be hiding the key to Alzheimer’s disease. And we may have a new strategy to fight the threat that the global banana industry has been facing for decades.

Further references

• Tom Benson – Mitochondrial Transplantation Solves Mitochondrial Aging – EARD 2022 as fascinating talk on the effects of transplanting mitochondria to hosts
• Stressed tissue and cellular burn-out? Enter the Mitochondrial Cycle Mitrix Bio CEO and Founder on mitochondrial degradation – and how it drives aging and lifespan.
• Zen and the art of mitochondrial maintenance: The machinery of death makes a healthier life Ageing, metabolism and mitochondria. More evidence that the cellular clean up processes remove dysfunctional cell machinery such as mitochondria.
  • “aging can be considered a sort of mitochondrial disease. If we could clear out mitochondrial damage, we would improve healthspan and longevity.”