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Coffee Reduces Suicide Risk

coffee-beans-cup

Regular commenter Michael Reynolds passes on word that people who drink more coffee are less likely to kill themselves.

Harvard Gazette (“Coffee drinking tied to lower risk of suicide“):

Drinking several cups of coffee daily appears to reduce the risk of suicide in men and women by about 50 percent, according to a new study by researchers at the Harvard School of Public Health (HSPH). The study was published online July 2 in The World Journal of Biological Psychiatry.

“Unlike previous investigations, we were able to assess association of consumption of caffeinated and non-caffeinated beverages, and we identify caffeine as the most likely candidate of any putative protective effect of coffee,” said lead researcher Michel Lucas, research fellow in the Department of Nutrition at HSPH.

The authors reviewed data from three large U.S. studies and found that the risk of suicide for adults who drank two to four cups of caffeinated coffee per day was about half that of those who drank decaffeinated coffee or very little or no coffee.

Caffeine not only stimulates the central nervous system but may act as a mild antidepressant by boosting production of certain neurotransmitters in the brain, including serotonin, dopamine, and noradrenaline. This could explain the lower risk of depression among coffee drinkers that had been found in past epidemiological studies, the researchers reported.

In the new study, researchers examined data on 43,599 men enrolled in theHealth Professionals Follow-Up Study (HPFS) (1988-2008), 73,820 women in the Nurses’ Health Study (NHS) (1992-2008), and 91,005 women in the Nurses’ Health Study II (NHSII) (1993-2007). Caffeine, coffee, and decaffeinated coffee intake was assessed every four years by questionnaires. Caffeine consumption was calculated from coffee and other sources, including tea, caffeinated soft drinks, and chocolate. However, coffee was the major caffeine source — 80 percent for NHS, 71 percent for NHS II, and 79 percent for HPFS. Among the participants in the three studies, there were 277 deaths from suicide.

In spite of the findings, the authors do not recommend that depressed adults increase caffeine consumption, because most individuals adjust their caffeine intake to an optimal level for them and an increase could result in unpleasant side effects. “Overall, our results suggest that there is little further benefit for consumption above two to three cups/day or 400 mg of caffeine/day,” the authors wrote.

The study itself (“Coffee, caffeine, and risk of completed suicide: Results from three prospective cohorts of American adults“) is gated, naturally, but the methodology is summarized in the abstract:

Objective.To evaluate the association between coffee and caffeine consumption and suicide risk in three large-scale cohorts of US men and women. Methods. We accessed data of 43,599 men enrolled in the Health Professionals Follow-up Study (HPFS, 1988-2008), 73,820 women in the Nurses’ Health Study (NHS, 1992-2008), and 91,005 women in the NHS II (1993-2007). Consumption of caffeine, coffee, and decaffeinated coffee, was assessed every 4 years by validated food-frequency questionnaires. Deaths from suicide were determined by physician review of death certificates. Multivariate adjusted relative risks (RRs) were estimated with Cox proportional hazard models. Cohort specific RRs were pooled using random-effect models. Results. We documented 277 deaths from suicide. Compared to those consuming ≤ 1 cup/week of caffeinated coffee (< 8 oz/237 ml), the pooled multivariate RR (95% confidence interval [CI]) of suicide was 0.55 (0.38-0.78) for those consuming 2-3 cups/day and 0.47 (0.27-0.81) for those consuming ≥ 4 cups/day (P trend < 0.001). The pooled multivariate RR (95% CI) for suicide was 0.75 (0.63-0.90) for each increment of 2 cups/day of caffeinated coffee and 0.77 (0.63-0.93) for each increment of 300 mg/day of caffeine. Conclusions. These results from three large cohorts support an association between caffeine consumption and lower risk of suicide.

One explanation of the Cox proportional hazard model, of which I had never previously heard, is available here [PDF]. But the key takeaway is that this isn’t simply raw correlation; the researchers used a sophisticated method of isolating the effects of caffeine consumption on suicide rates from the other variables.

That’s important here in at least two ways. First, since suicide is a relatively rare event, we’re dealing with rather small numbers. Second, we want to make sure that the directionality is clear. That is, the sort of people who drink a lot of coffee might simply be less likely to kill themselves than the sort that doesn’t.

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About James Joyner
James Joyner is the publisher of Outside the Beltway, an associate professor of security studies at the Marine Corps Command and Staff College, and a nonresident senior fellow at the Atlantic Council. He's a former Army officer and Desert Storm vet. He has a PhD in political science from The University of Alabama. Views expressed here are his own. Follow James on Twitter.

Comments

  1. Andrew in Toronto says:

    But how likely are coffee drinkers to kill someone else?

    Highly-rated. Helpful or Unhelpful: Thumb up 55 Thumb down 18

  2. Sean says:

    I’m curious if they included regular coffee drinkers that were unable to have their daily coffee.

    Highly-rated. Helpful or Unhelpful: Thumb up 32 Thumb down 3

  3. Sammie Jo says:

    @Andrew in Toronto:
    That only happens when we DON’T get our coffee. lol

    Highly-rated. Helpful or Unhelpful: Thumb up 42 Thumb down 2

  4. SFC MAC says:

    How much money was wasted on this bat-shit stupid study?

    Highly-rated. Helpful or Unhelpful: Thumb up 58 Thumb down 23

  5. Discrete Entropy says:

    It should be noted that the demonstrated link still can not be deemed as causal. At the risk of sounding nerdy, the biggest issue with the identification strategy is that the unobservables are contolled for via a random effects (RE) specification. The key assumption, which is unrealistic here, is that when using a RE approach the researcher must assume that the Xs (observables) in the model are uncorrelated with the random effect. If the controls and unobservables are not uncorrelated, then you get biased and inconsistent parameter estimates, including the parameter estimate on coffee consumption. Notice that even the authors use the word “association” and not “causation.” Causality is extremely hard to pin-down.

    Hot debate. What do you think? Thumb up 19 Thumb down 9

  6. Chris says:

    Due to the “Jitters” one cannot hold the gun steady enough, and the sleeping pills just spill to the floor.

    Highly-rated. Helpful or Unhelpful: Thumb up 57 Thumb down 7

  7. zonable says:

    How much did this wasted research project cost the taxpayers? Hmm? Another college research project that basically tells us nothing.

    Hot debate. What do you think? Thumb up 20 Thumb down 20

  8. Barn Cat says:

    @Andrew in Toronto: If you get in the way of our first cup of coffee in the morning you’re toast.

    Highly-rated. Helpful or Unhelpful: Thumb up 28 Thumb down 1

  9. Aquakidney says:

    @SFC MAC:
    Try this experiment: Drink some coffee and see if it causes you to develop a modicum of scientific curiosity and to stop worrying about all the money that isn’t spent directly on you.

    Hot debate. What do you think? Thumb up 17 Thumb down 7

  10. Dave says:

    This only applies if you’re drinking *real* coffee…if you’re guzzling that Starbucks swill, you deserve to poison yourself.

    Hot debate. What do you think? Thumb up 17 Thumb down 12

  11. Peter Courtenay Stephens says:

    PLease stop giving Pelosi, Reid, Boehner, McCain and Obama any more coffee.

    Highly-rated. Helpful or Unhelpful: Thumb up 71 Thumb down 3

  12. Peter Courtenay Stephens says:

    There a whole lot more, but that will start the ball rolling.

    Sic Semper Tyrannis !

    Like or Dislike: Thumb up 6 Thumb down 1

  13. Frank says:

    @SFC MAC: Who pays for these bat-shit stupid studys? I’m pretty sure WE do.

    Like or Dislike: Thumb up 9 Thumb down 8

  14. Duude says:

    Does anyone else get the impression that the coffee industry invests more money in studies of the benefits of coffee than America invests in cancer research.

    Like or Dislike: Thumb up 6 Thumb down 10

  15. Bob says:

    Crazy world! This will cheer people up: WORLD OF DEBT (funny music video)
    https://www.youtube.com/watch?v=99xsqxzJnXs

    Like or Dislike: Thumb up 0 Thumb down 2

  16. JustMe says:

    People who watch more TV and play more video games are less likely to be killed in traffic accidents.

    Does this mean that these activities make one a better driver?

    No, it means that they spend more time on their couch, and less time driving.

    .

    Like or Dislike: Thumb up 12 Thumb down 5

  17. scott says:

    coffee drinkers are more likely to kill researchers wasting government tax dollars through lame blood sucking money grabbing grant schemes.

    Like or Dislike: Thumb up 14 Thumb down 3

  18. Caffine assassin says:

    The preferred beverage of SOCOM

    Like or Dislike: Thumb up 2 Thumb down 0

  19. artemis133 says:

    I’d probably kill myself if I DIDN’T get my coffee every day!

    Like or Dislike: Thumb up 4 Thumb down 1

  20. CoffeeFreak says:

    People who commit suicide are less likely to drink coffee.

    Like or Dislike: Thumb up 13 Thumb down 0

  21. Dan says:

    I don’t know the term but not sure of cause and effect Are people taking coffee because they want to do something meaning they have purpose more than the caffeine saving lives. Kinda like hot people have more sex cuz they’re hot, duh

    Like or Dislike: Thumb up 5 Thumb down 0

  22. a real coffee drinker says:

    can we do this same study on any psychotropic medication. oops it wouldn’t work.

    Like or Dislike: Thumb up 0 Thumb down 0

  23. voiceoffrance says:

    In a 2007 double-blind study, researchers in Berlin took 40 participants, 20 of whom had just committed suicide and 20 of whom had just purchased coffee. Initial research indicated that, when presented with a cup of coffee, those who had just committed suicide were far less likely to accept the offer. Whereas, those who had just purchased a cup of coffee took a second cup at a rate of 75% (15 participants). Thus, the study concluded that if you are indeed dead, especially by suicide, the propensity to drink coffee diminishes greatly as compared to those who have just purchase a cup of coffee. -Johnson et al.

    Hot debate. What do you think? Thumb up 17 Thumb down 4

  24. Jon says:

    That’s because their hands are too jittery to hold the gun still.

    Like or Dislike: Thumb up 5 Thumb down 0

  25. JR says:

    Hold the Aspartame and you should be ok. If you are using artificial sweeteners in your coffee or other drinks, then essentially you are committing suicide.

    Like or Dislike: Thumb up 5 Thumb down 8

  26. Billy Bob Williamson says:

    @JR: Where did you get your tinfoil hat?

    Like or Dislike: Thumb up 6 Thumb down 3

  27. ONTIME says:

    I trust this poll about as much as I trust algore and his questionable wisdom…

    Like or Dislike: Thumb up 11 Thumb down 1

  28. Rose says:

    There have seen studies on the good health benefits of coffee in past. What gets me is those that are afraid of good old fashioned coffee (food police), and try to dictate saying coffee is bad. I was a college outdoor fair for the public. The venders were told, no coffee allowed. Pop was all over the place. Coffee is from a coffee bean, grown on a coffee bush. Not a mixture of water, sugar, fake flavor and other chemicals as pop is. Any time I see a study on the health of natural food I am happy.

    Like or Dislike: Thumb up 4 Thumb down 1

  29. Peanut says:

    Please refer to this study when investigating the high cost of a college education.

    Like or Dislike: Thumb up 2 Thumb down 0

  30. Jack says:

    They could only survey the people who did not kill themselves.

    Like or Dislike: Thumb up 4 Thumb down 2

  31. Buffmuffin says:

    Heroine addicts are really low on the suicide lists too..

    Addicts are too busy finding another fix to really do a lot of soul-searching about their lives.

    Like or Dislike: Thumb up 3 Thumb down 0

  32. Gene says:

    Could it be that coffee drinkers are more likely to be “on the move”, therefore more active, therefore working, and therefore not idle and not depressed? And that the idle are more likely to engage in introspection and self-pity, and are more likely to be depressed and kill themselves?

    This is an absurd study. Really, I think there are far better things to look at with research dollars.

    Like or Dislike: Thumb up 6 Thumb down 2

  33. Melvin P. Arbuckle says:

    How about a study on how to keep parasites from breeding?

    Like or Dislike: Thumb up 4 Thumb down 2

  34. Lee D. Rorman says:

    All kidding aside, my youngest son was a heavier than average coffee drinker, and he committed suicide.

    Like or Dislike: Thumb up 2 Thumb down 0

  35. caboosemon says:

    @Andrew in Toronto:
    Why kill yourself when there are so many democrats and illegals.

    Like or Dislike: Thumb up 6 Thumb down 3

  36. brent says:

    Billions of dollars and decades of conflicting studies, we’re still wasting our time and money with coffee studies?

    Like or Dislike: Thumb up 2 Thumb down 1

  37. jojopittsburgh says:

    @Andrew in Toronto: I agree, it is like them telling us the percentage of people who eat tomatoes that will turn out to be serial rapists. Since most people eat tomatoes, what in the heck would the study show. This is a ridiculous study, no doubt paid from Government Funds. Whoooppieee

    Like or Dislike: Thumb up 1 Thumb down 2

  38. Rose says:

    @Lee D. Rorman:I am sorry for your loss.

    Like or Dislike: Thumb up 3 Thumb down 0

  39. JDB Esq says:

    It’s because we’re always looking forward to our next cup of coffee. I also have a stock answer for anyone who asks me, “What time is it?”, I answer, “It’s time for coffee.”

    Like or Dislike: Thumb up 3 Thumb down 0

  40. michael reynolds says:

    I’m going to invoke the well-respected and widely-accepted 3R rule – the Reynolds Rule of Research – which holds that the reliability of any research is in direct proportion to how much it validates my personal vices.

    Like or Dislike: Thumb up 5 Thumb down 0

  41. JDB Esq says:

    @Melvin P. Arbuckle: Do you mean ‘democrats?’

    Like or Dislike: Thumb up 0 Thumb down 0

  42. jojopittsburgh says:

    What percentage of people who eat tomatoes are also serial rapists? That would be as relevant a study as this one. There is no way to link coffee drinking with murder or suicide or anything else, as too many other factors are shared by coffee drinkers . For instance, don’t most people who drink coffee also read newspapers? Or don’t they also wash windows once a year? I mean this is such a stupid study, I can’t believe anyone published it.

    Like or Dislike: Thumb up 0 Thumb down 2

  43. JDB Esq says:

    @Jon: Hey!!!

    Like or Dislike: Thumb up 0 Thumb down 0

  44. Russell12334 says:

    Is that because they get the caffeine high so bad they can’t hit the side of their head?

    Like or Dislike: Thumb up 1 Thumb down 0

  45. Surreal American says:
  46. Samuel cuevas says:

    @zonable: Why would people thumb down what this person said? His question is 100 percent valid and the answer is completely obvious. We the tax payer funded this stupid study through grants given to them. Fact. These commie universities get these funds and instead of researching something worthy of investigation, they piss the dollars away on this.
    But, I thought these same genius’, the better of our society, had discovered coffee to be bad for us to consume, ow wait, I mean good for us…… No bad…… Ow its good again. Okay, I see.

    I awaite the next study which will show drinking coffee causes free thinking in a university, and in extreme cases child birth. Then, it will again be bad.

    Like or Dislike: Thumb up 5 Thumb down 1

  47. Brad says:

    B.S. Correlation without causation. Suicides are caused by depression and other psychoses and are exacerbated by not having anything to do (joblessness, single, loneliness). Coffee drinkers are more likely to have something to wake up to, hence the need for coffee. Coffee does not prevent suicide.

    Like or Dislike: Thumb up 1 Thumb down 0

  48. Occam says:

    I’ve done a similar study. I’ve discovered that people who eat at Taco Bell are more likely to fart.

    Like or Dislike: Thumb up 5 Thumb down 1

  49. Juan Valdez says:

    I make my coffee so strong I could pave the highways with it. Due to drinking such strong coffee, I never have such thoughts of suicide and am always looking forward to another day. The only exception to bad thoughts is when I get to work and then I wish I could turn around and go home so I could go fishing instead.

    Like or Dislike: Thumb up 2 Thumb down 1

  50. 9007paul says:

    I wonder if Starbucks or Folgers provided any funding for this total waste of time?

    Like or Dislike: Thumb up 0 Thumb down 2

  51. Justin Smithers says:

    Well I guess that leaves out all the Muslim suicide bombers then. Maybe, instead of all that coffee-drinking that devout Muslims (excuse me, I mean, Islamists) engage in, because consumption of alcohol is forbidden by Islam, they should pop out once in a while for a beer instead.

    Like or Dislike: Thumb up 1 Thumb down 0

  52. ShelBel says:

    Less side effects than antidepressants and cheaper than therapy. Sign me up.

    @ Lee D. Rorman: Sorry for your loss.

    Like or Dislike: Thumb up 1 Thumb down 0

  53. Stuball says:

    Please Mr. President… give up coffee!

    Like or Dislike: Thumb up 4 Thumb down 0

  54. Serdse says:

    junk science.Note people who have killed themselves are less likely to drink coffee.

    Like or Dislike: Thumb up 1 Thumb down 0

  55. Ken says:

    Absolutely!

    I simply CAN’T kill myself!!!

    HAHAHAHAH!

    COFFEE COFFEE COFFEE COFFEE!

    Hey, can I mow your lawn? Clean your house? Maybe I can come over and we can chat? It’s early still, only 2 am on Sunday morning. There’s plenty of time, and plenty of coffee left!

    -Ken

    Like or Dislike: Thumb up 2 Thumb down 0

  56. hwk says:

    @Discrete Entropy:
    Lord have mercy! You want people to take the methodology of the study into account? We can’t just accept whatever the brain-dead journalist wrote for human interest sake? I better check what People Magazine and John Stewart have to say about this. All we really need to know is what hip celebrities say. We don’t need to bother thinking about “studies”. Who needs that kind of headache? It’s almost as bad as caffeine withdrawal — which will be covered by Dr. Phil on his next show.

    Like or Dislike: Thumb up 2 Thumb down 0

  57. Smarly says:

    What on Earth is natural about the article being gated?

    How about, “the article is gated, outrageously, since the research itself or the research it cites or at the very least the development of the internet which was probably somehow instrumental in conducting the research was paid for by the government, e.g. you and me, but if you want to check it out and pay the scum who put it behind a pay wall, click here”

    Like or Dislike: Thumb up 1 Thumb down 0