Sitting for a long time shrinks your brain even if you exercise

73 codexon 42 5/16/2025, 12:32:32 AM alz-journals.onlinelibrary.wiley.com ↗

Comments (42)

lwo32k · 3h ago
The issue is not that people's brain degenerate. Cause the rest of the body is physically degenerating too. And most people would naturally die by the time they hit retirement age before symptoms of mental decay show up, as was the case before we got modern pharma and surgical procedures.

But since we have more fixes for physical degeneration than mental degeneration, we see most sedentary people kept alive through medication and constant surgeries well into their 80s and 90s while there is nothing much to reverse whats happening to the brain.

Having worked for a while at a hospital, I feel people who really haven't lead active lives or are just naturally less active or don't like too much activity fall into this trap, where the medical system will keep them physically alive for few decades longer than in the past. They need to be told this could be a trap. Instead we keep them alive, let their brains degenerate and study them like lab rats.

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rajnathani · 27m ago
The study could have potential control issues, for example those sitting excessively would less likely travel and explore new places or be outside at social gatherings, both these small examples would potentially help stimulate the brain (loneliness is directly correlated with dementia risk [0]).

[0] https://www.nia.nih.gov/news/loneliness-linked-dementia-risk...

cko · 5h ago
As someone who started a fully remote job (sedentary) 1.5 years ago, this worries me a bit. I've been reading that those giant bouncy balls and treadmill desks are a gimmick and that standing still for a long time gives you varicose veins.

What is a good routine? Do I switch positions (right now I'm slav squatting) and maybe throw in some short bouts of exercise every 30 minutes?

stuaxo · 12m ago
Adjustable height desk wasn't cheap but definitely has been good.

I try and do my stand up meetings actually standing up, and .. most meetings (it's great for being more aware generally).

But the majority of the day is sitting, maybe I should get one those yoga balls to sit on.

rogerrogerr · 4h ago
Treadmill desks aren’t a gimmick IME. I use one every day, I swear it helps with focus and generally feeling good. I’ve found out I can walk for longer than I can stand. Make sure to set a 3° incline to save your knees.

I’d recommend trying it. This guy overanalyzed the whole topic, great resource: https://ocdevel.com/walk/guide#why_desk

AuryGlenz · 1h ago
I concur, they’re far from a gimmick and the days I don’t put my treadmill under my desk I’m dragging by noon. You’d think it would tire you out but it absolutely does the opposite.

Plus some days I burn something like 1,000 calories. That’s a pretty big bonus.

ensocode · 2h ago
2nd this. I've been using a treadmill desk for years now—walking about 4 hours a day while working. It’s cut my sedentary time in half. I definitely feel less fatigue, and overall more energized. Highly recommend trying it.
koonsolo · 1h ago
I also agree! I was afraid mouse and keyboard work would be too difficult, but actually it's not. Your wrist rests on the table, and so no problem at all.

https://writings.stephenwolfram.com/2019/02/seeking-the-prod... is the article that did it for me!

Wolfram even walks in the forest while working on his laptop. Haven't tried that one myself :D.

jeffbee · 4h ago
It's not clear that a treadmill would even register as activity by their method, which requires sustained acceleration of the wrist, which wouldn't be happening if you can keyboard. For that matter, riding a bicycle at 40kph wouldn't count as activity, either.
amluto · 4h ago
A bike at 40kph can have quite a lot of vibration. How much depends on the road and the bike.
duttish · 4h ago
A memorable quote from a physiotherapist I spoke with ages ago, "the best position is the next one". The variety is the key.
mkbkn · 3h ago
That's a profound statement. Thanks for sharing.
user_7832 · 4h ago
Honestly as long as you’re talking decent care of your health in other aspects (exercise - cardio and strength training, diet, enough sleep, avoiding stress if possible), with a bouncy ball seat (or even a standing desk) you’ll be good enough. You might have a few % issues statistically compared to someone who does the same but doesn’t have a desk job, but proper lifestyle has a multi fold effect - way stronger than a few %. If you occasionally get up and gently stretch (say every hour) and get the blood flowing, that’s probably almost all the way there.

Don’t forget, even though desk work is relatively new to the last century/industrial revolution, humans have been sitting for a long time - traders and teachers, scholars and students (probably not a good example sample but you get the idea). You’ll be fine.

kunzhi · 4h ago
20 years of desk work here. Both remote and in office.

The key is to make movement a regular part of your life. Mix up the movement like another commenter said.

For myself, I try to get outside and walk in the morning for about 30 minutes before work. It's a lot easier working from home than dealing with a commute, of course. I exercise 3-6 days a week also (with a mandatory rest day). I also have a walking pad treadmill thing that I pull out from time to time.

During the day I build in iron-clad breaks, including booking 30 minute out of office breaks in my schedule so I know I have protected time to get out and walk.

If I find myself with a spare moment, I do some squats. Sometimes with weights; I keep a pair of adjustable dumbbells in my office (they go up to 50 each). If I have even just 10 minutes between meetings, sometimes I will step outside for a 5 minute walk.

It's a lot of work for sure. And some days it really feels like work.

But over time if you keep it at you won't need as much discipline as you did in order to start. Think of brushing your teeth - that's a good habit most people manage to build and it's automatic for most.

Last thought - learn about yourself and your body. Try physical therapy before you need it from an injury. Try barbell lifts or other heavy weights. Try stuff you might think is "woo" like Alexander Technique or Feldenkrais. Try Crossfit. Try yoga. Try running. Try martial arts. Try dance. Try road biking. Keep trying stuff until you figure out what's for you.

Hydrate. Don't eat shit. DO NOT SMOKE! Watch your alcohol intake (or whatever else you're into). Get good sleep.

And especially if you're a man - don't kid yourself. You are not invincible and you are not immortal. You have to learn to take care of you and no-one else is going to do it for you. :)

Good luck. <3

ta988 · 5h ago
What if it is the opposite and beeing sedentary is a marker of cognitive decline (in this case genetic, but maybe it is also the case for other risk factors).
somenameforme · 4h ago
The good ole 'a glass a day of wine is healthy' issue. For those that don't know - it isn't. The numerous studies that found that all failed to account for a really simple issue. People who are unhealthy tend to give up drinking more frequently than those that aren't, even if for undiagnosed reasons.

So it turns out that people that were drinking a tiny amount of alcohol, but not enough to start seeing the endless negative affects of alcohol, were healthier than those that drunk none, but only because of this bias. The right amount of alcohol, so far as health is concerned, is zero.

It's quite insightful to see how this error then spawned a whole new series of 'approved' explanations for why wine was supposed to be healthy for you, such as antioxidants or whatever. In many fields everything remains extremely ad hoc - from brain plaque to serotonin, and I'll even add in intentional partial reps!

verisimi · 2h ago
I didn't know about this, thanks for the explanation.

> It's quite insightful to see how this error then spawned a whole new series of 'approved' explanations for why wine was supposed to be healthy for you, such as antioxidants or whatever.

Your analysis provides a very nice example of how science studies can be meaningless. And that this isn't a problem, as long as someone is making money. How many years did we see yet another study being rolled out about France, red wine, red wine extracts in pill form, etc. And yet all that literature is based on a pretty obvious false assumption. That no one was inclined to correct.

Der_Einzige · 3h ago
Most of reality is just simpsons paradox again and again and again...
thayne · 5h ago
Or there are confounding factors. Like diet for example, or what these people are doing while they are sitting.
max_ · 3h ago
When ever I sit for along time its to read a book or consume educational content (podcasts, non-ficton films).

I usually feel more knowledgeable afterwards.

What are some good cognitive tests to take (a part from IQ tests)?

plsbenice34 · 2h ago
The real article title says there is an association, while the HN title says there is causation ("Sitting for a long time shrinks your brain even if you exercise"). Very bad
NetRunnerSu · 1h ago
φ matched orders in daily life...

https://dmf-archive.github.io/

ch4s3 · 5h ago
807 ± 97 minutes sitting is a long time, around 13 hours.
electromech · 5h ago
Hold my beer...

...

On second thought, grab me another beer.

morkalork · 4h ago
Walking to the bathroom to pee out all the beer counts as moving right?
actinium226 · 3h ago
I see 3 problems so far:

1. Looking at the data, a linear regression is fit to data that looks anything but linear, calling into question the validity of the model

2. The units in some of the table are unclear, but overall it's not clear to me how much the brain shrinks in this data. As in, how significant of an effect is this? And I'm not talking about statistical significance.

3. This is correlation not causation. Maybe if your brain shrinks you can't focus long enough to move around.

sinuhe69 · 2h ago
Yes. I also see problems in other areas: -they didn’t define the threshold for sedentary behavior beforehand, so it could be they just move the threshold to hack the p-value. At least, they could analyze with different thresholds then publish the results open for interpretation.

- they didn’t control the effect of normal aging in older people. 7 years is a long period and by older people we can expect a decline in cognitive performance regardless of their life style. What we interest is however how much the sedentary live style contributes additionally to this decline.

- because the authors rely solely on the smartwatch data and put all kinds of movements together (sitting, walking around, laying down), we can not see whether changing posture and moving around can help.

- most importantly, they didn’t isolate and control for the amount of cognitive work. Doing cognitive demanding work is known to delaying worsening symptoms in AD and related diseases.

inverted_flag · 8h ago
I wonder if this holds up in younger adults as well.
readthenotes1 · 5h ago
Based on figures 1, 2, 3, I wonder if it holds up in older adults
j_bum · 4h ago
Yep, I had the same exact thoughts.

Would like to see the partial residuals plotted...

Are they over fitting their model? I cannot understand how we can look at a set of data like that, see that there are, perhaps, *maybe* some associations, and then make such serious conclusions from the stats.

DemocracyFTW2 · 2h ago
Please sit down and let me walk you through the figures
electromech · 5h ago
n = 404 p = 0.003

I'm too dumb to understand how that math works.

zxexz · 5h ago
It doesn’t. At least not in a way that’s, at best, misleading.
gonzo · 5h ago
Perhaps if you sit some more…
ziofill · 4h ago
Is it just me or those scatter plots feel silly to fit with a straight line?
iammrpayments · 3h ago
Yes, but I never finished my “Intro to statistics” book, so I can’t confirm
ekianjo · 4h ago
Not uncommon. Most of "science" is bad regression models applied on cloud of points. And then they think it means something.
nessbot · 4h ago
Sounds like the thought process behind this comment.
Supermancho · 3h ago
Don't talk about yourself that way.
reassess_blind · 3h ago
Did you just put science in quotes.
Supermancho · 2h ago
Some studies are useful science. Some are bunk. Some we don't know until long after when they are replicated or are never spoken about again because they have no signal or utility. It's under the practice of science, to some degree.
ekianjo · 44m ago
You most published papers can't be reproduced? So in effect most of it is pure junk passing for science