How has the curse of aging affected your mental capacity?

You might get better answers / discussion if you asked:

How has aging affected your intellectual capacity?

Referring to aging as a curse creates a bias. Furthermore, calling it a curse is false. Aging is a fact of life - at least at this point. Best to embrace it. Resistance is truly futile.

But to answer your original question: Aging has had some affect on my capacity. But what I've lost in quantity, I've gained at least 10x in quality.

I've also become, and perhaps this is personal, focused less (and less) on knowledge and fact, and more on understanding. That is, how things connect. What makes people - including myself - and systems "tick". It's enlightening, and certainly not a curse.

Not the age is my problem, but hearing loss and the need for adapters. I can't wear them 24/7 and when not wearing, I notice a dumpiness in my brain. Over the years I notice that it become difficult to follow by hearing, I need something to read and little more time to think about and to understand the topic. But it's just my perception. May be it's the age and dumpiness of hearing is just a coincidence. Can't sort it out.

But, accumulated experience is even more worth than sharp thinking. Experience accumulation is a kind of byproduct of sharp thinking, that has been used by my younger me once in a while.

When working on programs I wrote a year or more ago, I have to re-read the comments and any documentation in order to recollect my thoughts on how it works and why I did things the way I did.

When working on large programs, I need to keep multiple portions visible in different windows/screens in order to grok the interdependencies.

I don't enjoy reading books as much as I used to.

Mental math is way harder.

Neuroplasticity or lack thereof also way more noticeable. Previously I feel like I could learn a new subject/topic pretty quickly, now it's taking way more time. That said at the same time having noticed this "problem" I now always do a double take on whether I need to really learn something new(cos opp. cost is way higher), so at the same time more pre-commitment => less garbage in my brain.

I seem to be doing fine: a little less sharp at some things, a lot of accumulated experience helps with others (the usual "fluid" vs "crystallised" intelligence thing)!