I've hit my early 30s and I've started noticing that I'm far more prone to inappropriately replaced words, can't memorise long strings of digits as well as I used to be able to, and so-forth.

Generally, the body's ability to take punishment starts to decline in the thirties which can manifest in mental impairment, but someone who's taking good care of themselves should actually enjoy a pretty well-tuned brain. Biologically speaking there should not be enough damage to justify capability deterioration for a long time to come.

All things being equal, I'd say it comes down to the use-it-or-lose it mantra: your brain gets better in areas where it's being used, and atrophies in others where it isn't.

Mental competence is not a hallmark of youth. In fact, problem-solving performance in many fields should go up with experience, and only degrade very late in life when things like ischemic attacks, prions, cellular garbage, and the natural neuronal die-off rate all come into play as significant factors.

This is key.

I have noticed the same symptoms as the parent. And I can't be blamed by not challenging my brain enough - I am learning Haskell, doing a side project and there's the day job.

If I had to measure myself, I'd guess that I'm working at 40% of what I was in my 20's (I'm 34). However, I probably have sleep apnea (I say probably because my doctor asked me to get a bunch of exams and I'm not through with all of them yet, only thing I know for certain is that the blood pressure is higher than it should be). I self medicate with copious amounts of caffeine and yet I'm always feeling sleepy and hazy, as if I were not fully out in the real world.

So yeah, the other poster likely has some underlying health condition. Which could be as simple as not getting enough sleep. I can't function at all with less than 8 hours, while I could in my youth.

Adult acne? Itchy ears? Intermittent neck cramps? Progressive hair loss? Sleep better with a fan blowing over you? Acid reflux?

If so, possibly try getting into a tub, drawing a moderate layer of water, and then performing breathing exercises into the water. In/out with force. Nose/nose, Mouth/mouth, Nose/mouth, yatta. Note: I did not relish the outcome, ymmv.

Repeat after: twisting torso, xing/unxing arms, alternating closed nostrils, plugging nostrils and pressurizing breathing tract + ears, vigorous activity (jogging)

Also, if the hair one is true, regularly brush your hair w/ a soft end comb. (I almost guarantee loss will stop)

Also, if the adult acne is true, try the opposite of common sense, and apply a thick skin cream (Aveno's decent) or a gellified salt like deodorant if it's not sensitive skin. Make sure to apply well to areas near openings to ears/nose/mouth/eyes. (You should do this anyhow as it slows your apparent age)

Also, if reflux, try high acidic/bitter/basic/spicy/salty foods and see whether they trigger/solve reflux and whether you sleep better/worse.

Also, possibly try sleeping fully enclosed within a sheet.

Not a doctor, your own risk, other standard medical disclaimers by non-pro.

Have you tried stopping? I mean, too much caffeine makes me sleepy too (not over the same say, but after a while).

It's really rather more associative fuckups, as someone else in the thread describes - even if I have the right word in my head, my hands may type something utterly different, which usually starts with the same letter and relates to what I was after, but differs.

As to memorisation - I'm talking having gone from being able to indefinitely retain 20+ digit strings on first sight to maybe half that, and often finding I've switched a digit.

As you say, sleep is probably a major component in this, and I can't recall sleeping more than a few consecutive hours in years - usually manage six hours of restless sleep before throwing the towel in and getting back to doing whatever it was I was doing when I nodded off. Can't bear to spend time just lying there. There's too much to do.

It sucks to lose the horse power, but I more than make up for it by driving the car in the right direction. I suspect the decline will continue, but in many ways I look forward to what I will be able to accomplish when I'm older.

That's a really young age to have any sort of marked age-related cognitive decline. It might be explained by something else--even something as "simple" as insufficient quality sleep or stress, both of which can wreak havoc on cognitive ability.

This is very true for me, much to my surprise. I used to get by on 3 to 4 hours every night but that seems to have really caught up with me. If I don't get 8 hours minimum now I'm woozy the rest of the day.

It is like some sort of intoxication, which is fitting, because one of the things sleep does for us is clear toxins from our brains.

That's eerie, I have that too. Especially when it is totally quiet in the house. At first I thought it was because I heard the refrigerator, but I switched that off to rule it out. Then I powered down the whole house and the low humming remains. I'll have to try this when I'm totally rested to see if it goes away then, I never made the link to lack of sleep.

Read that a while back, look at the possible explanations, especially tinnitus might be a possibility.

Anyway, I think of it as an interesting phenomenon, it doesn't bother me much (except when trying to fall asleep, once I notice it it is impossible to stop noticing it).

Another thing is that I seem to be "sensitive" to some electronics. For instance, I cannot hold a cell phone to my head for more than a few minutes and I even have to take breaks when listening to music on headphones. The feeling I get bears some similarity to my sleep-deprived state, so I have wondered about a relationship there, if not just a further reduction of my tolerance of electronics.

I can hear the dear foraging around the house at night, and if a car passes on the nearest highway (a few kilometers away) I can hear that clearly too. But during the day all those sounds vanish, masked by the ever present background noise level which is far higher than it is during the night. And my hearing is actually not nearly as good as it used to be.

One simple solution I've found is to play really low volume white noise, that seems to instantly drown out all of it but strangely enough is very hard to detect by itself.

I never noticed any 'sensitivity to electronics'.

But, I also know we lose our high-frequency hearing as we age. I wonder if that somehow increases our sensitivity to the low frequency range.

In any case, I'll have to try the white noise. Seems like it could help with sleep quality, which might in turn reduce sensitivity to it.

Having said that, simply going to be earlier is not likely to help weed out most of these disorders. Go to a sleep doctor and see what they say. Also, are you getting more irate? For many people it's a lot easier to get angry when they lack sleep.

Also a good point about giving it a couple weeks. Chronic sleep deprivation can't be fixed with a night or two of "catching up".

Is this an example of that? Did you mean 'placed' or do I mis-understand you?

Definitely didn't do this in the past, I find it disquieting, but it's hardly insurmountable!

This is why it's vital to do challenging mental exercises like crosswords puzzles, etc. ("use it or lose it.)

Generally though, the article makes sense because the common cell machinery of nerves (which don't divide as much as say intenstine or dermis cells) can be hampered by underlying issues affecting organelles within nerve cells, which then manifests as functional, quantitative deficit at the macro level.

Very few people face the same level of obligations at 20 as they will at 30 or 40.

There's also the Dunning-Kruger effect: the better you get at something, the worse you feel you are at it... presumably, all of us have made strides towards mastering our craft in the last 10 or 20 years....

On balance, I'd choose the connection-making brain over the raw-power brain.

I've been suffering from health issues for the past four years. That's why I'm interested in the brain (I suffer from extreme brain fog, and by extreme I really mean extreme; I can't have a conversation with anyone face to face, and I even have some issues when chatting with people. It takes a long time to really think about what I need to say. I still cannot understand how I'm managing to go through college).