Coffee: An antidepressant and religion preventative?

A recently published study found a correlation between higher rates of coffee drinking in women and decreased risk of depression. Naturally, that finding made headlines. But blogger Scicurious has a really nice analysis of the paper that picked up a significant flaw in the way the data is being interpreted. There was a correlation between drinking more coffee and a lowered risk of depression. But that wasn't the only correlation the researchers found—just the only correlation they made a big deal of in their conclusions.

On her blog, Scicurious lists the other correlations and explains why it's hard to draw any solid conclusion from this data set:

1) Smoking. The interaction between depression risk, smoking, and coffee consumption was “marginally” significant (p=0.06), but they dismiss it as being due to chance because it was “unexpected”. Um. Wait. Nicotine is a STIMULANT. It is known to have antidepressant like effects in animal models (though the withdrawal is no fun). This is not unexpected.

2) Drinking: heavy coffee drinkers drink more. But note that they don’t say that drinking coffee puts you at risk for drinking alcohol.

3) Obesity: heavy coffee drinkers are, on average, thinner, but not more physically active. They do not conclude that coffee drinking prevents obesity.

4) Church going: heavy coffee drinkers are less likely to go to church. Less likely to go to church, less likely to develop depression…heck, forget depression, maybe coffee prevents religion now! Now THAT would be a heck of a finding.

Here’s the thing. I do believe that high coffee consumption correlates with decreased risk of depression. But a lot of other things do as well. I am not convinced that the high coffee consumption wasn’t part of a lifestyle that correlated with decreased risk of depression, maybe they have stronger support networks or less incidence of depression in the family. It could be many other things.

Image: Coffee, a Creative Commons Attribution (2.0) image from dyobmit's photostream


  1. Then what’s with all the churches running coffee shops, both inside the church buildings and elsewhere? Hell, we have one micro-roaster here in my small town, and it’s run by a local church. Damn fine coffee, too.

  2. Speaking as a Unitarian, I can categorically say that coffee consumption does not always reduce church attendance or religious practice. Old joke: Show and Tell, religious symbols. Patrick stands up and says “I’m Catholic and this is a crucifix.” Samuel stands up and says “I’m Jewish and this is a Star of David.” Alexia stands up and says “I’m a Unitarian and this is a coffeepot.”

  3. Coffee is *AWESOME* Don’t need no stupid studies telling me that, I felt it, heck I sometimes even chew the bean, why? Because it is *AWWWESOME* Twice over.

    No wait, let’s be subjective here, is there any other substance we consume that would come from the poop of animal? There you go *AWESOME*

  4. Coffee prevents religion? Not for Lutherans, where the scriptures sometimes seem to read:
    “Where two or more are gathered in my name…serve coffee.”

  5. I take Zyprexa to ward off depression and I drink coffee to stay awake. I also drive a car with four tires and speak English. I live in a house and I have not pets. Correlation is not causation.

  6. Man (Woman), I’m sick and tired of this stupid inconclusive science shit. I’m switching to decaf and voodoo.

  7. “I am not convinced that the high coffee consumption wasn’t part of a lifestyle that correlated with decreased risk of depression…”

    It may very well be correlated.  There may be a ton of correlations.  As long as no one tries to claim that such correlation is evidence of a causal effect (without good reason), who cares?  It very well be due to “many other things” but that doesn’t matter.  Correlation is just a mathematical statistic.  It doesn’t matter if it’s actually caused by something else.  That doesn’t negate any math showing correlation.  The amount of lemons imported per year from Mexico is highly correlated with the amount of traffic deaths in the US per year.   You can’t “disprove” that.  It’s true!   But it’s also entirely meaningless and without point if what you really care about are causal effects.  Don’t get hung up on whether or not correlations exist.

    1. >>…it’s also entirely meaningless and without point if what you really care about are causal effects.

      Um… I kind of think that was her point since she was addressing the much touted “coffee-depression correlation” being used as a causal argument.

  8. I can’t wait for PZ Myers to secretly replace the local parson’s Postum with Folger’s Crystals. Let’s see if he notices the difference, and also that there is no God and that he’s been living in a prison of socially malignant self-delusion, and hopefully he tears off his clerical collar and urinates on it right there in the street because science! (p=0.001!)

    And, of course, for Pat Robertson to call for a boycott on any coffee he’s not personally selling through the 700 Club online store.

  9. Now seems like as fine a time as any to ask: is there coffee after death? Seriously, because if there isn’t, I’m not going.

  10. Speaking personally, my agnosticism coincided with my adoption of coffee. Of course, it happened at the same time I went to college and started piecing together philosophy and history a bit better. 

    Still, I have a few friends who recently became Unitarian. If I ever find the need to seek out a congregation of coffee-drinking agnostics….

  11. Seems like the Mormons and Jehovah’s Witnesses alone would be enough to account for the “church-goers drink less coffee” stats.

  12. I know that when I’m feeling depressed or anxious, caffeine just increases my anxiety.  If that’s true for other people, then that alone could explain the correlation: depressed people are less likely to drink coffee.

  13. The correlation that jumped out to me was:
         Less likely to go to church, less likely to develop depression.
    Never mind the coffee; Religion causes depression!

    1. Well, I can’t comment on that, but the inverse is likely.  Sometimes the depressed just want some answers, guidance, certainty, even if it’s illusory.  Religions also tend to try to provide their brand of support to people in crisis, and it’s easy to believe anything when it comes with a smile and a shoulder.

      1. That’s exactly what I was thinking. In fact, I wonder if religion is correlated with depression because depressed people seek out religion, and religion is correlated with decreased coffee consumption because of Mormons.

        1. The opposite is true according to wikipedia’s criticism of religion page:

          “…An analysis of over 200 social studies contends that “high religiousness predicts a rather lower risk of depression and drug abuse and fewer suicide attempts, and more reports of satisfaction with sex life and a sense of well-being,”[90] and a review of 498 studies published in peer-reviewed journals concluded that a large majority of them showed a positive correlation between religious commitment and higher levels of perceived well-being and self-esteem and lower levels of hypertension, depression, and clinical delinquency.[91][vague][92] Studies by Keith Ward show that overall religion is a positive contributor to mental health,[93]…” (The section continued in the same vein for a while)

          1. The next paragraph says: “However, as of 2001, most of those studies were conducted within the United States.[97] According to a 2007 paper by Liesbeth Snoep in the Journal of Happiness Studies, there is no significant correlation between religiosity and individual happiness in Denmark and the Netherlands, countries that have lower rates of religion than the United States.[98]”

            I suspect the source of happiness is socialization and a sense of belonging. Since the United States is majority Christian and much socialization takes place in church, happiness indirectly correlates with religion here. In Europe, which is more secular and less churched, there is less correlation. I suspect that the connection between religion and happiness is even greater in countries with Sharia law, since people who don’t hold to the majority religious viewpoint are made unhappy.

  14. I gotta ask, does anyone have access to the article?

    I have to wonder if the poster read the study properly and knew that  a higher average can’t be stated as a finding if the difference isn’t statistically significant. Studies like this can easily be misinterpreted when a difference appears between groups that is not statistically significant.

    1.  Yeah, the critical response read to me like a well-informed layperson’s interpretation of a scientific article based on the presentation of that article by the media.  And…  pow! Turns out she’s a scientist, so I’m wrong there, but she is focusing her critique on media representation of the study – but aiming it at the study authors.  This is incredibly unfair; we don’t decide how the media will interpret our findings, and can’t control what they’ll decide to say.  If

      Also, she shows a clear bias in favor of laboratory research, which isn’t surprising…  but I’m still frustrated by it.  We could do animal studies of caffeine all day and it would not tell us about what coffee does to people, particularly in the case of something as complex as depression.  Both types of study – physiological and social – are valid! 

      The article is here:

      I’m not in a position to go dig it up and draw my own conclusions right now, but I’m skeptical.  People devoted to particular methods are often critical of other equally valid methods, and unless the study’s authors said “this is a cause and treatment!” she’s not being fair to criticize them on those grounds.
      It actually looks like they were careful about causation – they have longitudinal data, lagged it, and are *still* claiming there could be a reverse causal effect. 

      Dunno.  Media representation of science is often awful, that’s not news.  :(

  15. Church going: heavy coffee drinkers are less likely to go to church. Less likely to go to church, less likely to develop depression…heck, forget depression, maybe coffee prevents religion now! Now THAT would be a heck of a finding.

    It’s not that coffee prevents religion, coffee is religion! And it’s therefore protected by the Constitution, I say! They’ll have to pry my coffee from my warm, caffeinated hands…

  16. This criticism is bogus; this blogger seems unaware that “marginally significant” is in fact a very real statistical term and not one to be made fun of.  Marginal significance refers to the margins of a standard 2×2 table: the interaction they report as being marginally significant is just that.  Marginal does NOT mean “almost” in this context.  Scicurious should learn more about statistics before she snarkily dismisses jargon she doesn’t understand.

    1. The other bit that made me cringe: “but they dismiss it as being due to chance because it was “unexpected”. Um. Wait.”

      This is an excellent example of what you aren’t supposed to do. By chance, it is entirely possible to get non-real correlations in data that appear significant. This is why you can’t just run an experiment and then look for patterns, find them, and claim you’ve done anything exciting. You must test a particular hypothesis. If you see something else, fine, great, you’ve got some interesting fodder for your next experimental direction. Run the experiment again, gather more data, and see if your correlation is still there.

  17. I would think that this is confounded by people with friends and family being both happier and busier, therefore being more in need of coffee to keep going.  And people who have (what seems to them at least to be) important things to do that give purpose to their life, like many doctors or CEOs, tend to be busier as well and usually have less time for rest.   Were these factors controlled for?

    1. Have you been touched by His noodley appendage today? :P

      In other news. In Islam, addictive substances are forbidden… with the exception of caffeine.

      Some of us converts joke that if caffeine were forbidden, we’d switch to Christianity.

  18. people that drink coffee are working on more worthwhile efforts than burning time being told things they already know. don’t kill people or F your best friend’s wife? Got it. I have have work to do. 

Comments are closed.