Mid-life burnout/overwhelm and long term low-level stress can all contribute, in my and my team's. experience. You've not mentioned gender either - menopause in women can cause brain fog etc.
You end up feeling like "25 year old me was so much sharper and quicker, wtf?!"
Assuming that: you work in tech; you're probably not neuro typical; you've developed so many coping strategies for life's ups and downs you don't even think about them;
... have a look at what does stick in your mind. Are you spending a lot of brain power on underlying anxious thoughts, stuff that's always flying around your head that maybe focusing on work helps to ease? Is your mind acting like something's hogging the CPU?
Bluntly, most tech people are either some kind of ADHD or Aspergers, or both. Well-Adjusted Adults (/s) don't generally want to spend all day speaking in extremely logical terms and fighting esoteric error messages from their computer. IMO a lot of scrum practices and tech company culture is centered around making work more tractable for people with these kinds of neurodivergances.
In relation to what GP was talking about, if you have spent most of your life with either of these conditions it is likely that part of your normal every-day functioning involves employing some set of defense mechanisms and learned reactions. Part of that in the past may have been developing an affinity for computers. It can be hard to navigate a world in which most people seem to understand more about interpersonal interaction than you do, and/or where most people are cool with ambiguities that don't make sense to you. These strategies take up a lot of CPU power in your brain, and can (among a whole host of other things) make your memory more foggy because you are busy spending all your time in a kind of low-level survival mode.
As an aside, poor autobiographical memory is a really common side effect of ADHD, a condition which can be philosophically framed as having a difficult time connecting to the past or future as well as other people can.
Maybe this is not very HN-style of a response, but I want to sincerely thank you for your careful answer. I’m probably learning something about myself just now. Something I’ve always suspected, but didn’t put a finger on it until now. Will investigate this further.
You end up feeling like "25 year old me was so much sharper and quicker, wtf?!"
Assuming that: you work in tech; you're probably not neuro typical; you've developed so many coping strategies for life's ups and downs you don't even think about them;
... have a look at what does stick in your mind. Are you spending a lot of brain power on underlying anxious thoughts, stuff that's always flying around your head that maybe focusing on work helps to ease? Is your mind acting like something's hogging the CPU?