Does #altitude ameliorate #obesity? Color me skeptical

Theoretically, one might think that it would.

The exertion of working in oxygen-lessened air might cause people to burn more calories. Or, the fact that thinner air is less insulating, and it's generally cooler at higher elevations, might cause people to burn more calories to maintain constant body temperature.

That's why, why friend Leo Lincourt posted this link from the Public Library of Science, with the map image at top included, I was intrigued.

And skeptical.

Very skeptical. 

First, there's a lot of Mormons in high-altitude areas of the West. And, per a response on the PLoS page by the author, he admits that, while the study allowed for some demographics, it did NOT allow for religion. Given strong Mormon dietary strictures, including no drinking of alcohol with its "empty" calories, that seems like a pretty serious omission.

As I posted at the PLoS site, the only relatively easy way to determine whether it's likely that Mormonism is at least as causal as altitude or not is to compare obesity in high-altitude areas worldwide versus neighboring flatland areas, i.e., Himalayas vs Asia, Alps vs Europe and Andes vs South America.

I'll be skeptical until I see such research.

Second, the altitude-obesity correlation isn't very strong outside the Rockies.

It looks decent but not fantastic in the Sierras. It appears almost nonexistent in the Cascades.

Third, has this research been "normalized" to allow for larger margins of error in sparsely populated high-elevation counties? I don't know.

Fourth, don't these relatively numerous lower-obesity counties in flatland Florida, flatland New England and New Jersey, and lowland east Texas and coastal California, also undermine any obesity-altitude correlation claims. 

The study author does say that hypoxia is demonstrated as a cause of anorexia and weight loss. He doesn't say how much weight loss it causes. Nor does he say whether this is short-term laboratory-induced hypoxia, or what.

After all, we know that, speaking of the Andes and Himalayas, in the two highest-altitude areas of our world, long term residents, the Inca and Tibetans, actually have their bodies adjust to bind oxygen to hemoglobin more efficiently, or otherwise use oxygen better. Now, in more transient American society, such effects might not "take" for several years. So, obesity as a weight-loss aid might only be of shorter-term benefit.

Jamieson also doesn't say how much less oxygen is needed for the effect. This study mentions an Austrian study that used 1,700 meters, or about 5,500 feet, as a "baseline" altitude for noticeable benefits from hypoxia. In that case, almost all the Mountain States ... just about all of Colorado, Utah and Wyoming, most of Montana, much of New Mexico and Arizona, and a fair portion of Idaho ... should have no darker shading than the medium orange, third level of obesity, if there's much strength to the correlation. However, the map shows MASSIVE variations in those states.

Beyond that, failure to control for Mormonism in the US West, in this study, is questionable.

And, that Austrian study was of only 22 people, and for only three weeks.

Update, April 12: There's more reason to disbelieve these claims. Turns out "fat Southerners" are just more honest about their weight than other parts of the country, often. The Northern High Plains states are the biggest weight liars, and the Southeast among the mildest, research shows.

Here's the money quote on a possible "why," too:

"It is hard to know exactly what is going on, but my speculation is that people in the South are telling the truth more," (biostatistician George) Howard said. "Perhaps there is not as much stigma connected to obesity as say someone in California, or in this case, Minnesota."

Sounds plausible, at least. And, that white area in western Colorado? Ski resort heartland. Think rich, white, Volvo-driving, latte-sipping neoliberal narcissists.

No wonder our school kids are science-ignorant

Our teachers aren’t teaching it.

One-quarter of public school science teachers teach either open creationism or stealth creationism, aka intelligent design, in their classrooms. And 50 percent of them, or one-eighth the total …

called creationism a “valid scientific alternative to Darwinian explanations for the origin of species,” and the same number said that “many reputable scientists view these as valid alternatives to Darwinian theory.”

What’s the solution?

The study's authors note that courtroom victories — classroom creationism has consistently been struck down in U.S. courts — is apparently insufficient to guarantee an accurate depiction of evolution. Nor will rigorous state science standards, like those recently passed in Florida, do the trick. Instead they recommend teacher certification requiring the completion of an evolutionary biology course.

I totally, 302,875,106,592,253 percent agree. (That’s 13 to the 13th power; what could be more anti-superstitious than that?)

See here, at PLoS, for full survey of teachers.

A couple more thoughts on the PLoS antidepressants study

I add these observations based on quotes the Public Library of Science report on antidepressants and their alleged minimum effectiveness on milder depressions.

First, per a comment on a blog, two of the studied drugs are SNRIs, not SSRIs. The PLoS study doesn't even list SNRIs as a type of antidepressant. I quote:

Antidepressants include “tricyclics,” “monoamine oxidases,” and “selective serotonin reuptake inhibitors” (SSRIs).

Second, would you describe improvement of more than halfway from the baseline to “significant” as “marginal”? Again, I quote:

A previously published meta-analysis of the published and unpublished trials on SSRIs submitted to the FDA during licensing has indicated that these drugs have only a marginal clinical benefit. On average, the SSRIs improved the HRSD score of patients by 1.8 points more than the placebo, whereas NICE has defined a significant clinical benefit for antidepressants as a drug–placebo difference in the improvement of the HRSD score of 3 points.

(The word "marginal" is used more than once throughout the study.)

“Moderate” or even “modest” would be acceptable words. “Marginal” overstates the case.

Next, given what I’ve already said about p values, I'm not sure how much weight I would put on a total of 5,100 people in the 35 trials umbrellaed in the meta-analysis. I'm not sure how much significance I would find in one medical study that had that many people, especially if studied over a short time period.

That said, given the “lag” anti-Ds can have, the FDA is also remiss on some of their study criteria, I don’t doubt. Is two weeks too soon to allow a drug switch? In cases of severe depression, you may feel you have to try something else, which you do for the patient's sake, of course, but that should perhaps "ding" the study in some way.

That said, given that we still know little about brain chemistry, even if anti-Ds are shown to be of little effect some day, I'm not even sure that we can, today, say they are either effective or ineffective, with any degree of confidence.

The PLoS antidepressants study, the ‘looseness’ of medical research statistics and ‘faith’ in meta-analysis

Way too loose of p-values for false positives in studies, in medicine (and social sciences) compared to natural sciences, is one reason to not read too much into any individual study that claims antidepressants are ineffective, like the Public Library of Science meta-analysis of individual studies did.

P-values of the same looseness as in medicine/social sciences have been used to claim intercessory prayer actually works on sick people (halfway down the linked page), for example, or here (two-third down the linked page):

Targ's paper is not the only questionable study on the efficacy of prayer that has been published by medical journals. The editors and referees of these journals have done a great disservice to both science and society by allowing such highly flawed papers to be published. I have previously commented about the low statistical significance threshold of these journals (p-value of 0.05) and how it is inappropriate for extraordinary claims (Skeptical Briefs, March 2001). This policy has given a false scientific credibility to the assertion that prayer or other spiritual techniques work miracles, and several best selling books have appeared that exploit that theme. Telling people what they want to hear, these authors have made millions.

Also, per a blogger, I came across a good statement on how many people misunderstand p-values in general:

First, the p value is often misinterpreted to mean the “probability for the result being due to chance”. In reality, the p-value makes no statement that a reported observation is real. “It only makes a statement about the expected frequency that the effect would result from chance when the effect is not real”.

In short, as I’ve tried to explain to people over at Kevin Drum’s blog, p values in medicine are simply too loose.

But, as the study’s authors claim, doesn’t meta-analysis take care of all those p-value problems? No.

Meta-analysis, no matter how much it’s defended, can’t totally cover that up.

I’m not saying that the results of a meta-analysis are no stronger than the weakest study in its umbrella. I am saying that, with p values as loose as they are in health/medicine (and social sciences), is that no massive amount of individual research studies being included under one meta-analysis will make the meta-analysis’ results anything more than a little bit stronger than the best individual study.

In other words, in medicine, and in social sciences, meta-analysis adds a very modest bump, nothing more. The problem is, most people believe it does much more than that when it doesn’t.

Or, to put it another way, meta-analysis is no better than the material it’s analyzing.

So, what’s needed is medical studies to continue with the p of 0.05, because we don’t want to risk screening out potentially life-saving study, but, to re-crunch research studies at the same time. I’m not saying we need to do that with a p of 0.0001, or 1/100 of 1 percent, like the natural sciences, especially physics, normally do. But to re-crunch with a p of 0.01, or 1 percent instead of 5 percent? Absolutely.

Research that made the 5 percent cutoff but not the 1 percent cutoff would be categorized as “worthy of further study but without any immediate conclusions from it being acceptable.”

A sidebar benefit would be that a lot of alt-medicine research would get a less than full imprimatur.