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Thinning in brain regions important for memory linked to sedentary habits (sciencedaily.com)
152 points by neverminder 3 months ago | hide | past | web | favorite | 83 comments

> This study does not prove that too much sitting causes thinner brain structures, but instead that more hours spent sitting are associated with thinner regions, researchers said.

This is a bit of a non-story. The article doesn't go into what measures were taken to eliminate confounding factors, and it seems from the way it's worded that not many were taken. Maybe people who have a more sedentary lifestyle also tend to come from a lower social background, thus are more prone to physical and mental diseases. Or maybe people who sit more tend to be more obese, and it's really obesity that's associated here. It doesn't take a genius to think up more possible confounding variables. Also, a cohort of 35 people is tiny.

> Maybe people who have a more sedentary lifestyle also tend to come from a lower social background

My favorite confound is when Pauling convinced many reasonably educated higher SES people that vitamins were a miracle cure-all. Suddenly multivitamins did correlate with higher health outcomes! (Until later studies untangled this and found little broad effect, aside from specific vitamins during pregnancy or specific deficiencies.)

Sort of a pop science self fulfilling prophecy. Or when we do things we think are smart, sometimes we pollute the evidence.

Pop Science. Nice...

> This is a bit of a non-story.

You just summed up Science-daily. Every single day there's a revolution in sciences or understanding if you believe their articles.

I'd add that sitting is extremely board. That is, sitting and doing what? Watching (mindless)TV? Or reading (more engaging materials)? Sitting on a bar stool? Or at a desk chair at the library?

Much like your point about obesity, understanding the nature of the sitting seems essential before any worthy conclusions can be made.

If this were the first of its kind yes, but given that there are numerous studies suggesting that exercise is good for the brain its reasonable hypothesis. Rather than a non-story I'd say it adds to a body of evidence for a strong hypothesis.

The premise of the study is what you said (http://journals.plos.org/plosone/article?id=10.1371/journal....).

However, this studies falls short of demonstrating that "strongly", or the claim than sitting makes some part of your brain thinner.

When looking at the data, age is the most important contributing factor, but the authors do not perform any multivariate measurement of age vs physical activities vs sitting time. Maybe it's because they don't feel the need to since, and they state it:"As with total MTL thickness, physical activity was not associated with any of the subregional thicknesses."

By redoing this study, including a many more participants, across the country, actually measuring physical health parameters instead of simply doing a survey. I also think they should have used non-parametric tests. I don't believe, and they don't show any indication otherwise, that their sampled population had a normal distribution, was in sufficient numbers, and the some of the metrics were independent from each others.

Since their data set is available and rather simple, one can readily redo the tests and find out that the strongest relation is Age vs MTL, that Age vs Physical activities also correlates strongly, as does Age vs Sitting. Contrary to what the authors reported, sitting and activities also correlates... So yeah that's a bust!

Also, maybe the cause and effect is backwards. People who lose brain capacity could become less active?

In my early career I was a car seat engineer which gave me a life long interest in seats. If you look at historical chairs it is amazing how recently the comfortable chair was introduced. I peg it at around 1920, about 30 years after the Morris chair, which was the beginning. Think of the colonial era Windsor chairs. You can imagine great thinkers sitting in them pulled up to their desks creating and thinking. But no way could you sit for the 10-12 hours a day most HN readers do. Go back further to images of classic times. Sitting devices were definitely not capable of being used for extended periods. So yes, it is worth thinking about the impact of comfortable furniture on how much we sit. But later. I am getting up to get a cup of coffee.

What can we do to support healthy physical posture and movement whilst also maximising productivity when working with with electronic representations of textual and numeric data?

There are some obvious avenues to explore -- but it is not clear if anything is going to be available to consumers in the near future.

I'm really hoping VR headsets can provide a workspace where people can lay down or stand. The keyboard replacement in those positions might be hard to figure out.

That’s one of the easier problems. I just bought a split wireless keyboard. It actually feels alright just laying it in my thighs to typ.

There are quite a few things that can be done.

1. Get management in on the importance of ergonomics in modern work-life. Like needs to be a large portion of budget and discussed with the board important.

2. Culturally teach the importance of ergonomics in computing. Make it a part of prereq college basic IT courses.

3. Interface types will change this equation. VR, wireless-VR, AR, advances in motion capture, and in brain-computer interfaces will offer alternatives that will have to be adapted and evolved into (I'm rooting for a foss future myself, as it will be more agile in the evolutionary process which is ony one of many reasons foss software is superior to proprietary.)

4. Change the outlook on the desk space and it's function. I was in really good shape in the Marine Corps but I still found time to play pc games, which all know can suck hours away, so I designed a workout program for at the desk in my barracks room. I turned what was a sedentary area into an active area just by changing my approach. For example, during CS matches, the rule was every death is max set of dips (using chair arms) squats (by pushing chair back out of the way) pushups, curls, or pullups, etc. Then rotate every time. I've also used balance balls as chairs in order to force me to focus on my core and ab static strength. There are many examples and each person is different, but the desk doesn't have to be a lazy place. (If you are interested in this I would start with horse stances to work with leg strength first and get the bloodflow to the gluteus maximus which is what excessive sitting restricts.)

Ultimately, I've been saying for a while that VR with room sensing seems really promising to me because I envision a future of VR workout sessions, which could be really fun by gamification and get people in shape! It wouldn't be that hard to ship a kettlebell with a motion tracker in it.

I have a game project (planned GPLclient/CC?contentbysub model) with a long goal of getting into that territory, but had to narrow scope away from recently. I'm mostly waiting for VR on gnu/linux to get better, hoping the Vive Pro has made progress in that area.

Reminded me of this: https://en.m.wikipedia.org/wiki/List_of_chairs

I love that that's an article, and the ridiculous geekiness it takes to appreciate it. I think we're overdue for someone to write a brief history of chairs, like has been done for salt, longitude, and light sources.

I was certain this would already exist but had no source. Now that I’ve finished with that rabbit hole I liked the look of this one most - chair history is surprisingly interesting.


Sitting devices were definitely not capable of being used for extended periods.

If only someone had invented the cushion.

Nothing about what people were actually doing while they were sitting? Watching TV? Staring into space? I don't know how to take something like this seriously (after reading this article in its entirety, not the linked paper)

Seems like a critical piece of information. You could say that people who take frequent brakes from their work to go outdoor and stand there for a while are likely to die younger. That's smokers behavior.

If it was random sample from general population then I'm betting on watching TV. Studies seem to suggest that if you are doing a lot of cognitive work it is good for your brain and memory. Apart from the somewhat new trend of standing desks, most jobs that are about thinking are done in a sitting position.

“UCLA researchers recruited 35 people ages 45 to 75 and asked about their physical activity levels and the average number of hours per day they spent sitting over the previous week.“

Isn't UCLA among the top universities in the world? How can they publish a research like this (asking a few questions to 35 people) and draw such formidable conclusions? The title sounds like they've discovered something new that applies to all humans...

It becomes quite evident in studies like this, but nearly all social science related studies are based on the exact same pattern. For instance the emotional intelligence study, which has been repeatedly cited and been reasonably influential, was based on putting people into groups, having them do tasks such as [literally] writing a shopping list, and then showing that the groups that did the tasks most efficiently were not strictly composed of those that had the highest IQ. So therefore it was implied that individual merit alone does not determine results of groups, but rather some 'emotional intelligence' does.

It's absolutely atrocious logic since B is in no way implied from A. For instance to show this then you would need to, at the minimum, put the people that all individually do the best at e.g. writing a shopping list, into a group, and then compare them against people that individually do worse but score well on the [again literally] 'Reading the Eyes in the Mind' test that was used to measure 'emotional intelligence'. Of course that was not done, and I don't think it's unreasonable to speculate because we know what the result would be - and that's not publishable. Yet bad science paired with an astounding headline and you are suddenly good to go.

Yeah, a bit of a rant but it's incredibly disappointing how awful the social sciences have become. And that decline pairs ironically with a massive increase in the reporting of their results, which become ever more grand and increasingly clickbaity, in the media.

Are you equating IQ with merit? If so, you need to broaden your perspective.

My opinion is not relevant one way or the other. I am describing the study.

That's actually how statistics works. You don't need 100,000+ people to make a readily generalizable conclusion.

If the differences are significant, they'll appear with as few as 35 people, carefully selected, and give you a confidence level of X that it applies to a population size of Y.

Whilst I don't know the details of this particular study, I do recall doing homework problems about correlation confidence.

In layman's terms, maybe this example will help:

Imagine a study where they found that 100% of people who were "sitting" had bent knees. Essentially no one could bring their hips and ankles closer together without bending their knees. With such a significant correlation, you could generalize from a population of 10 to one of trillions so long as the ten was randomly chosen, and there were no other correlative factors.

Aside from things like false legs and injury bringing your hips and ankles together like that is a physical impossibility; that doesn't provide a good analogue. People sit with straight legs too, but if you test by asking people to sit on a chair it will show everyone sits with bent knees, where in fact lots of people sit on the floor, beach, or bed (say) with straight legs. FWIW I sit on a chair with straight legs, on top of my computer tower.

If you take a sample of 35 people in China you can with a reasonable confidence level say all people are Chinese, or perhaps a very small proportion aren't, depends how lucky you get. It's wrong of course, despite Chinese being the majority (17% according to Wikipedia).

It's fine as a preliminary, but it doesn't show anything useful yet other than the need to perform further study IMO.

A report on this should say something like "viability study suggests sitting and brain changes are related but doesn't provide enough confidence as yet". Which it sorta does, from this section on:

>"This study does not prove that too much sitting causes thinner brain structures, but instead that more hours spent sitting are associated with thinner regions, researchers said."

But either ScienceDaily or UCLA have not lead with that information, matching the current style.

Sampling is studied as a way to save time without running a census for every experiment. Many universities use this technique. An intro to stats course could probably be found on Coursera that will go into this.

Self-reported data? That isn't verified? That's nearly always a red flag.

How about using a set of long haul truckers? In a before vs after sort of why? Their hours behind the wheel is documented (or should be). I would presume they're sitting behind the wheel :)

In other words, tiny sample, results likely don't generalize, may also be false positive.

A "sitting is killing you" article based on a study of 35 people.

Is this going to launch another wave of conflicting articles published every-other-week saying how to minimize it?

"Eat fish 5 times a day while standing!"

"New study: fish 10 times while doing squats!"

"Latest: the fish does nothing! You need a 'weightless desk' in low earth orbit."

Man that last idea sounds sweet! I'm up for that whether it prolongs my life or not!

This seems to contradict another article posted on HN I read recently, which says memories are lost due to brain cell growth after physical activity!



Which contradicts yet another article which says that growing new brain cells can improve memory:


So which is it? I think we need scientists to take two contradicting studies and try to find out the root cause of a discrepancy, instead of making a third study. To do that, they need to record as much as they can, and a meta-study needs to look at the actual discrepancies that can account for a change.


> I think we need scientists to take two contradicting studies and try to find out the root cause of a discrepancy, instead of making a third study.

Yes, the shorter form being ;-) :

I think we need scientists.

I don't know if my brain has "thinned" but I do know that after sitting for years coding I started experiencing a pinched nerve in my back, and that ain't no fun.

I thought I was having a stroke the first time it happened about six months ago. I realized it was a pinched nerve after looking into it but it took several months to figure out exactly what stretches I needed to do to relieve and prevent them.

Where’d you track that info down?

Sorry for the slow reply.

I read up on the symptoms and since I didn't feel any "pain" it indicated it was a pinched nerve.

I started doing some stretches lying on my back and sometimes that stopped the "zinging" immediately but not every time. When it did I could feel my spine in the middle of my back "pop". And if I laid flat on my back I could feel my spine had hump in it.

I could also feel some tingling in my feet and legs before it would start zinging me out, so I got to know when they were coming.

One day when I felt the tingling I stood up and raised my arms straight up and arched my back backwards as far as I could and slowly lowered my arms by bringing them down while pulling them behind me as far as I could in a half circle motion. All kinds of "popping" noises happened and the tingling went away instantly.

Over the next few weeks I had just a few full on zingers and when I did that stretch they went away almost instantly. Since then I've made a point to do those stretches several times a day and I've not had a full blown zinger in over a month.

It was bad though. Damn near paralyzing on my left side and I could barely walk when it was happening.

Not OP, but I actually went to a physiotherapist. Well worth the investment if they know what they're doing.

Very very true. They’ve helped me immensely in the past.

"The researchers next hope to follow a group of people for a longer duration to determine if sitting causes the thinning and what role gender, race, and weight might play in brain health related to sitting."

This is just a preliminary study. It´s too soon to get any conclusions. But, it´s a good starting point for a hypothesis. I will like to see the results of the final study, even that is going to take a long time.

I have seen many times links between sedentary life and illness. But this one looks promising as tries to find a mechanism on why this happens at the brain level that may affect cognition.

And yes, before doing a more expensive study, they asked 35 people for a preliminary study. You don´t spend a lot of money to try to prove something without first trying to disprove it on the cheap. Translation for developers: before spending a lot of time to test something you first do a smoke test. If it passes you invest the time to test it fully. Otherwise, you go back to writing code.

I wonder if this is true for physical inactivity in general? I suspect that using a standing desk instead of sitting down wouldn’t change the situation.

Interesting they do manual segmenting, who's working on image recognition to automate measuring of the various areas - presumably then all past scans [with patient acceptance] could be fed in to a system and the brain regions could be measured and classified.

The correlation graphs are awesome!


Not sure you could get a better randomisation if you tried with just 35 points??!

Perhaps people who are either predisposed toward unhealthy outcomes, or are currently experiencing them (whether they realize it or not) are more sedentary. Correlation does not establish causation.

Um yes, the title should be more like:

"Sitting correlates to Thinning in certain brain regions"

Is it bad to have a "thin" brain and good to have a "fat" brain now?

Can't this brain region become too large? What if the area is enlarged due to inflammation/swelling and these people with "thinning" are those without that problem?

If the brain is too large it is considered a problem: https://en.wikipedia.org/wiki/Megalencephaly

This guy apparently has the second largest brain ever measured, and he was a serial killer: https://en.wikipedia.org/wiki/Edward_H._Rulloff

The study was regarding density, not size.

Where are you seeing that? Also, fine density/volume/mass, does it really change the argument?

There is some optimal size for this region when it comes to certain functions, probably relative to the size of other regions. That size is probably suboptimal when it comes to other functions and there are tradeoffs going on.

The press release seems to be assuming that thinner is bad automatically.

> The press release seems to be assuming that thinner is bad automatically.

Well, it's not unreasonable.

I don't know of any literature that says that a sedentary lifestyle is healthy for the brain, but a lot of it has found the opposite. I would like to avoid anything that reproduces the neurological effects of being sedentary.

>"I don't know of any literature that says that a sedentary lifestyle is healthy for the brain"

Here are two I found:

>"More sedentary behavior was strongly predictive of more depressive symptomatology and, unexpectedly, of better cognitive performance." https://journals.humankinetics.com/doi/pdf/10.1123/japa.13.3...

>"Self-reported sedentary behavior was related to better performance on one cognitive task (trails A; p < .05)." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4861254/

Obviously these are "undesirable" results, so you have to look a little bit deeper to find them.

Yeah I do believe it makes a difference, because brain atrophy is linked to a range of cognitive impairments, for example strongly correlated with Alzheimer's disease.

But you're right on the last point though, about assuming thinner is bad automatically. Heavy and chronic cannabis usage has been linked to an increase in density, but a reduction in total volume, which resulted in a slight overall decrease in IQ. The takeaway from all this being: Cognitive function is affected by a variety of parameters and we got more neuroscience to do still.

>"Heavy and chronic cannabis usage has been linked to an increase in density, but a reduction in total volume, which resulted in a slight overall decrease in IQ."

I wouldn't put much stock into these type of non-quantitative explanations wherein "this makes that go up which makes this go down", etc.

Usually the researchers measure a bunch of different things, analyze the data in a bunch of different ways, and only publish whatever is "significant". This works at the single lab level and multi-lab level since the "non-significant" results are considered boring and don't get published. By "usually" I mean this is standard behavior. You can call it p-hacking, file drawer effect, and more recently "forking paths":


>"Cognitive function is affected by a variety of parameters and we got more neuroscience to do still."

Sure, that was the case before these studies were done too though.

They're using "thinning" in the sense of "thinning hair". Generally lower density would imply fewer neurons and fewer connections. Since this is happening late in life, rather than during the pruning stage of development in youth, this would tend not to be a good thing.

Why do you think this?

It looks like this was the study (emphasis added):

Sedentary behavior associated with reduced medial temporal lobe thickness in middle-aged and older adults http://journals.plos.org/plosone/article?id=10.1371/journal....

As far as I know, thickness is a synonym for density. Quote from the article:

To calculate thickness, for each gray matter voxel we computed the distance to the closest non-gray matter voxel. In 2D-space, for each voxel, we took the maximum distance value of the corresponding 3D voxels across all layers and multiplied by two. Mean thickness in each subregion was calculated by averaging thickness of all 2D voxels within each region of interest.

I think it is literal thickness since they report the results in units of millimeters. (eg figure 2)

The authors explained quite carefully what they mean by thickness, as per the quote I provided. They are measuring the average distance between voxels in MRI scans. Since thickness is a measure of average distance in this case, it makes sense to provide it in millimeters like in the figure you mentioned. If you read the article, the authors make distinction between volume, surface area, and thickness under the "Discussion" part [0].

[0] http://journals.plos.org/plosone/article?id=10.1371/journal....

Their description sounds like literal thickness. They took the distance to the border (white matter) of all the points in a region. This is like the radius of a circle, and then multiplied by 2, to get a value like the diameter of a circle.

It does sound like quite a convoluted process but I don't see where you are getting anything like "density" from that description.

Also, reading the methods closer makes me think these are cherry picked results:

>"Once segmentation is complete, the original images are interpolated by a factor of 7, resulting in a final voxel size of 0.39 × 0.39 × 0.43 mm. Next, up to 18 connected layers of gray matter are grown out from the boundary of white matter, using a region-expansion algorithm to cover all pixels defined as gray matter."

Why 7? Why 18? These magic numbers shouldn't be there without some kind of sensitivity analysis.

Finally, you can see the dimensions of the voxels is something determined by their methods, not a property of the brains.

Where in the article did you read anything suggesting that "They took the distance to the border (white matter) of all the points in a region."? I read the article, but didn't find anything like that.

You quoted it (I guess besides white matter it could also be just to the pia):

>"for each gray matter voxel we computed the distance to the closest non-gray matter voxel."

I do admit that whatever they did is difficult to follow without seeing images of the transform etc (and figure 1 does not help), but the idea they are somehow measuring density seems impossible to me.

Within a given region, if there is more gray matter, and it is more clumped together, then the distance to nearest non-gray matter will be larger on average. This is what the authors call thickness.

The gray/white/pial matter is not randomly distributed in the tissue so that there would be more or less clumping of gray matter.

I thought maybe you had some expertise regarding how they processed the data that could somehow make this (extremely strange thing) happen, but you have not demonstrated it. I guess I do not know for sure what they did without seeing the code, but if that is what they measured it is the most bizarre thing I have heard of when it comes to analyzing MRI data.

No one in this thread, or in the article, has claimed that gray matter is randomly distributed.

Regarding your comment about how incompetent I am, and how extremely strange this MRI analysis is:

Measuring cortical thickness by MRI is a standard technique in neuroanatomy since 15 years ago. And really, a quick search of the literature would have shown you this. But I suppose that's too much to ask.

>"No one in this thread, or in the article, has claimed that gray matter is randomly distributed."

I simply cannot imagine what you think is going on in order for them to be looking at "clumping" of gray matter as a proxy for density of the tissue via MRI and calling this "thickness".

>"Regarding your comment about how incompetent I am, and how extremely strange this MRI analysis is"

I thought perhaps you knew some technical detail about their analysis pipeline, but you still haven't mentioned anything technical... so I just don't have any idea what you are thinking.

>"Measuring cortical thickness by MRI is a standard technique in neuroanatomy since 15 years ago."

Sure, here is the first article I found regarding "cortical thickness":

"The shortest distance between the pial surface and the white/gray junction is the cortical thickness at each point." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5561315/

That sounds exactly like what I would expect, nothing to do with density or clumping.

Like I already told you, in order to fix your ignorance of how researchers use jargon, you can go through the literature. I'm sorry, but I'm not here to teach you these things, and it's not really my concern whether you're informed or not. I can recommend using Google Scholar as a starting point if you'd actually (surprisingly) be interested in educating yourself.

Regarding your other comments about how the authors cherry picked their results and made up numbers in order to fabricate results, I can not take a stance.

Time and time again more evidence is propping up stating the benefits of exercise. I think Patio11 summed it up well, roughly stating that as we are all working with the same hardware(the body) then we should work to maintain it in top shape.

If you maintain your body in a weak state, it would seem that your body would have to maximize its output with a lesser performing system. Imagine trying to perform well when you have a heart that’s got 1/4 the performance of a well maintained one.

Imagine the downstream effects of all this!

Maybe people ages 45 through 75 are going through the period of life which we traditionally associate with both a lowering of physical activity and increasing difficulties in memory. Sure would be nice if they linked the study or seriously cared about critiquing it.

The real question should be whether both are also strongly associated with grey hair, number of grandchildren, and taste in film.

Here is the actual paper, for your reference. I'm appalled that ScienceDaily did not link this in their article.


Here is the activity survey:


The paper was confusing because they reported an average of 7 hours sitting each day and 1500 minutes per week of "physical activity" (3.5 hrs a day). So basically anything besides sitting and sleeping seems to be counted as physical activity.

It does sound like almost anything is counted as physical activity: "on how many days did you do moderate activities like carrying light loads, washing windows, scrubbing floors and sweeping inside your home"

Note that in the paper, they mentioned controlling for age. Also mentioned is that this data is preliminary, hence the low sample size.

Maybe people with thinning in brain region associate with memory overestimate the amount of time sitting because they can’t recall as accurately what they were doing in between sitting sessions...

Not even 3 months ago it was "standing desk users less focused, less productive". Which might be more about the kind of person a standing desk user is than it's effect.

My anecdotal experience tells me that those who adopt many efficiency boosting methods (standing desks, optimized keyboard layouts, various lifehacks, extreme customization of their work environment…) tend to be less inclined to focus on the actual work.

Yes. And television is bad for your eyes.


I just want a study that tells me the intensity and frequency of exercise that counter-acts the sitting plague.

By now, all sitting studies sound like they're stating the obvious.

Apparently, there's no _true_ offset for extended hours of sitting[1]. There might be some science/studies behind smart watches urging you to stand for a couple of minutes every hour, however.

[1] https://www.theatlantic.com/health/archive/2016/08/the-new-e...

A lot of people make a living sitting in a chair all day. What are we all supposed to do instead? The implications of this are pretty far-reaching.

> What are we all supposed to do instead?

Depends on how much you care and how able you are to compel yourself into action.

Almost every one of us reading this is in a position to abbreviate our work with physical activity at the very least. I just wager that most of us are too addicted to comfort to actually do anything about it in the face of the evidence. For example, we already know that a sedentary lifestyle is bad yet most people don't exercise.

what about the dual? moving, either walking, driving or longer always stimulates my brain. To the point that not moving I find myself very silent and believed I had a problem.

That's why I'm laying down.

Conclusion drawn from experiment on 35 samples? Must be kidding...

Taking issue with small sample sizes is a popular way for the layperson to chime in with criticism, but it is rather empty and uneducated criticism.

In statistics, sample size does not tell you if correlations are significant or not. Which is why it's amusing when someone thinks they are being a statistics pedant by pointing out a small sample size.

I think this is worth challenging. A small sample means there's a higher likelihood that the sample is not very random. It's often pulled from some easily available source, like a group of college students.

An idealized perfect random small sample might be just fine for statistics, but there's little reason to believe that's the sample we're getting. Small samples should be a cause for suspicion.

Anti clickbait tldr: Too much sitting is ASSOCIATED with thinning brain structures.

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