I started getting perceivably more stupid and slow at about 24.

Short answer: yes, at least at dan level. Read fast or lose!

My strength has leveled off an even been declining these last five years. Hard to say if age is a factor here. For me the main culprits are more work, getting married, having a kid and playing online poker.

The main factor is being obsessed about something if you want to improve and keep improving. Thing is that boring old daily life makes giving to that obsession harder and harder when you get more responsabilities. Boy that sounds boring for a gamer like me. Part of me wishes I was single and had no child. But I might love them more then I even love gaming

I know wouldn't be posting this because I am only 17, but I dare to say that the older someone is the stronger he/she becomes. I feel far stronger than when I was 15 - 16 and I am looking forward to 20.

_________________
Stefany, web programmer

i shouldn't be posting either (i am 20), but i guess that the progress you describe hits at some point its maximum and then the player naturally starts getting weaker. he will be of course still gaining more experience but at the same time his abilities to focus and read deep will decrease. you can see it very well at pros

what might be more important for amateur players is that job and family eventually come (for most them) and then it is much harder to devote enough time for go. this lack of time (and maybe interest) is in my opinion worse for your playing strength than are just your physical / psychical abilities

EDIT: hmm, i am mostly repeating what wrote Hicham above. sorry about that

_________________
Spilling gasoline feels good.

I might be wrong, but probably not.

Am I actually meant not strong in go, but strong in the life. But anyway, nice post.

_________________
Stefany, web programmer

But do you look forward at being 32? Or 55?

What I've found is that I have a harder time switching between blitz and slower game settings. If I play blitz with consistent settings for a while, I get used to it, but then if I play mostly slow games for month or so and then try going back to blitz, it's like I've forgotten how to play blitz and will start losing a lot of games on time. The real killer for me right now is the intermediate time settings.

For example:

Very fast: 10 minutes absolute. - This is actually not a problem, because I don't pretend that I have time to think about any move. Strangely, I actually do better at this setting than at intermediate. Both sides are playing garbage, but my win rate is fine. Maybe it's because I care less about the result here: I can always dismiss a loss by telling myself it is not a measure of my "true" go strength (as if such a thing exists) due to the insane time limits.
Intermediate / Fast: 1 minute basic time + 25 moves in 5 minutes Canadian byoyomi (usually called 1/5 on IGS.) Lose a lot against opponents I can beat at slower settings. Feeling that I have enough time that I should be reading, but once I start it's like I don't have time to finish.
Medium: 15 minutes or more basic time + 5 periods of 30 seconds Japanese byoyomi (or 25 moves in 10 minutes Canadian) - usually no significant feeling of time pressure. I probably play my best go here.
Long: anything more than 1 hour basic time - may just get tired in the endgame, especially if I played anything serious earlier in the day. Fortunately, I only play this kind of game one week a year, so I don't really train for it.

I'm seriously considering dropping the intermediate / fast time setting. It's just too much adjustment to play regularly at 3 different settings. That way, I'm either reading or not reading---there is no half-baked in between to worry about.

I'm 42 and have been playing about 7 years. I am therefore not fortunate enough to be able to compare to what I may have done if I had been playing in my twenties or earlier. 1/5 has always been a pressure time setting for me, but it's getting really bad. I discovered 10 minutes absolute almost by accident and it just seems easier to get used to. (My experience is that 10 second byoyomi throughout has a similar feel.)

I guess my experiment with ultra fast time settings has been motivated by running into players well into their 60s who play that way all the time. I figure if they can do it, so can I.

Finally, to shapenaji: is your change perception in any way correlated to when you started ADD meds? Some people I've talked to seem to feel they were "faster" before such treatment, but there is then this difficult question of whether that was real or just a subjective feeling. If your blitz results haven't actually gotten worse, maybe it's just a feeling.