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Comment by scotchmi_st | Hacker News Reader

> 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.

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> 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?

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