Resisting brain shrinkage: reminds me of a somewhat different but related report I heard in the past of a group of nuns who seemed to age very well such that their cognitive functions remained seemingly strong into old age. They donated their brains to research, and upon study significant shrinkage was found similar to some degree of Alzheimer's. I think the conclusion was that because they kept themselves so active and busy, whatever synaptic connections were necessary for their daily functioning were kept strong, alongside important life memories. Another strong case for how "retirement" is harmful.

Generally, the rate at which memory synapses weakens is similar across the general population (stability of a memory synapse), so for super-agers it is probably genetic.

I may not have a super-ager brain, but as a lifelong learner and brain-health lover I've placed all my significant memories into a spaced-repetition program I use for everything, and thus am able to recall at will all sorts of important memories in life. I'm keeping my important synapses strong.

There's another category besides super-agers: people with hyperthymesia: "a condition that leads people to be able to remember an abnormally large number of their life experiences in vivid detail. It is extraordinarily rare, with only about 60 people in the world having been diagnosed with the condition as of 2021." There's a documentary about these people. You ask them: what important event happened in your life on January 7th, 1980, and they can answer it accurately.