Major discoveries are made by top, top people - it seems not unlikely that past a certain age most people cannot remain top. The same is true with chess, which does not have the same administrative duties problem.
Anyway, you can look at the pages of Annals of Math and Inventiones and see that there is a good mix of ages.
How could you tell the age of an author of a random paper in either?
you also see people in their 20s make big contributions to many disparate fields, like Tao.
However, I strongly doubt the various parts and cells erodes any differently. Brilliant minds, bog standard glial cells. Their parts come with the same warranty we receive.
My experience is that ageing is a very similar process.
Acuity and ability in old age follows a very similar trajectory. Use it or lose it.
Whether you're an outlier or the mean, use it or lose it applies just as much.
The difference is, with top minds I find they receive so much external attention that it keeps them focused on their work in their 50s/60s/70s.
All the external plaudits and celebration simply fuels use it or lose it. The brilliant thing is, we can all leverage use it or use it, we just need to maintain our abilities to leverage it.
Use 100% of your brain. That's the most important thing.
Revv the engine to 100%.