Quote from nitro:
I appreciate the response, but I am either being unclear, or you are misunderstanding what I am saying.
What I am saying is that I am noticing distinct degradation in my capacity to concentrate for extended periods of time. I doubt it is anything I can cure with mental gymnastics. My daily regimen already includes a tremendous amount of that, as I am an avid reader, I program, am a chess player and bridge player, etc. But in all these areas, I see degradation in level of performance.
What I am saying is akin to saying that I have an engine and it has 120,000 miles on it, and I expect it to behave as if it had 5000 miles on it. In mathematics and in chess, it is "well known" that you are done with your best work by the age of forty, and it is a fast path downhill from there. I could never understand how that was true. Why should it be? Nah, it won't be true for me. Guess what, the experience is starring me right in the face, and as far as I know, there is nothing i can do about it.
The only thing I can think of is to exercise more vigorously, and to change my diet, but even that will probably only bring incremental benefits, and almost certainly only slow down the process. Worth a try though.
It is really annoying. The worst by far is, music doesn't sound as rich as it used to. That is not due only to hearing worsening, I am convinced that cognitively I am also not experiencing the same thing I used to.