Similar age, and I experience this most when I'm depressed (which is mostly seasonal for me, winter is often very unproductive and very foggy for me, if I don't get myself to somewhere with some sun).
Getting my depression sorted usually sorts the fogginess and mental sluggishness. Though I'm confident I'm not as quick witted as I was in my 20s and 30s. I have a lot more knowledge and a bit more wisdom but I'm not as "smart" as 25 year old me; I'm nicer and more empathetic, though, so that counts for something.
When I'm not depressed learning new things is slower and a bit more labored but not hugely so. I've been getting back into serious music study after years of only casual playing and I think I'm learning new pieces and techniques at almost the same pace I did when I was younger, though I'm basing that assessment on recollection which can be hazy after ~20 years.
I think there's also a tendency to lose the growth mindset as you age. I struggle with it sometimes. When starting a new project where learning a bunch of new stuff is required, there's sort of a grumpiness about it...it's like, "I've already learned and done real work in a half dozen programming languages, why do I have to learn another one?" With a dash of "I'm too old to be wasting time on these detours into obscure territory. I'm already an expert in all this other stuff, I should be focused on maximizing the value of that expertise." Even though, honestly, learning new stuff is more fun than the actual building things and using existing expertise is often boring and predictable; but this mindset gets in the way, anyway. It's quite a pickle to be in.
Getting my depression sorted usually sorts the fogginess and mental sluggishness. Though I'm confident I'm not as quick witted as I was in my 20s and 30s. I have a lot more knowledge and a bit more wisdom but I'm not as "smart" as 25 year old me; I'm nicer and more empathetic, though, so that counts for something.
When I'm not depressed learning new things is slower and a bit more labored but not hugely so. I've been getting back into serious music study after years of only casual playing and I think I'm learning new pieces and techniques at almost the same pace I did when I was younger, though I'm basing that assessment on recollection which can be hazy after ~20 years.
I think there's also a tendency to lose the growth mindset as you age. I struggle with it sometimes. When starting a new project where learning a bunch of new stuff is required, there's sort of a grumpiness about it...it's like, "I've already learned and done real work in a half dozen programming languages, why do I have to learn another one?" With a dash of "I'm too old to be wasting time on these detours into obscure territory. I'm already an expert in all this other stuff, I should be focused on maximizing the value of that expertise." Even though, honestly, learning new stuff is more fun than the actual building things and using existing expertise is often boring and predictable; but this mindset gets in the way, anyway. It's quite a pickle to be in.