Coffee: The new Prozac?

Posted on December 19, 2011


Dateline: 26 September 2011 // Posted by: Lauren Fergus
Source: Los Angeles Times

Story: “Caffeine’s buzz chases away women’s depression”

Summary: A recent news article in the LA Times has reported that a new research paper — “Coffee, caffeine and risk of depression among women” (published in the academic journal Archives of Internal Medicine) — reported that caffeine can reduce the risk of depression in women. Women who regularly consume the highest amount of caffeine in the study (which they do not specify the amount for) are reported to be 20% less likely to experience depression than those who drank little to none.

One of the researchers, Dr Albert Ascherio, says, “There’s no reason, from what we know, for people to cut back on their coffee consumption, unless, of course, it makes them feel bad.” They investigators added that “regular” coffee drinkers were less likely to be obese or to have high blood pressure or cholesterol. According to the article caffeine also is linked to lower risks of depression.

They do mention twice that coffee has also been associated with higher use of alcohol and cigarettes but altogether the article emphasizes the positive effects for drinkers of fully caffeinated coffee.

Why is this PseudoNews? In the original research article, the authors of the study offer the following important caution: “First and foremost, because of its observational design, this study cannot prove that caffeine or caffeinated coffee reduces the risk of depression but only suggests the possibility of such a protective effect.” However, the journalist who wrote the LA Times article never quite reviews the cautiousness of the authors of the scientific article she cites. She cites the investigation as one of confidence and neglects to report the cautions the authors give in the comment section of their paper.

The scientific article mentions a study in Finland, which found a J-shaped relation between coffee and suicide. When people drank more than 8 cups a day, coffee actually positively correlates with suicide. They mention that the current experiment did not actually look at high consumption since only .52% of their participants drank 6 or more cups of coffee, a point that the news article disregards.

The scientific article also states that “Caffeine may antagonize the adverse effects of smoking on depression through still-unknown mechanisms or may interact with genetic factors that predispose patients to smoking and depression.” Another apprehension the LA Times article neglects mentioning.

What features of pseudoscience are on show? The authors of the scientific article themselves note several of the problems with this research, one being vagueness in measurement. The study asked participants every two years to fill out a survey which asked about their caffeine consumption (among other habits), and occurrence of depression as defined by self-reported physician-diagnosed depression and antidepressant use. Both the time between report and the use of self-report make these measurements vague. Coffee drinking habits can fluctuate in the course of 4 years, and people’s estimations could be biased due to memory defects or socially desirable responding (essentially, such self-report measures constitute a form of anecdotal evidence). In addition, doctors’ diagnoses and medicating practices vary.

Lack of parsimony is another issue in this news report. The scientific article notes that the same results are not the same for all caffeine, like tea or soft drinks, the news report does not mention this and is relying on some unknown difference between the types of caffeine and caffeine intake.

The news article exhibits a possible confirmation bias when overall it neglects the caveats the original article gives. The original article emphasizes the lack of theoretical agreement between this article and such articles as the cohort study from Finland that shows a J-shape relation between cffee and suicide. The LA Times journalist appears to focus on the evidence that supports her point, that coffee consumption reduces the likelihood of depression.

The moral of the story: Women should not feel justified in drinking large amounts of coffee each day nor should they use coffee as a treatment for depression. It is not proven to reduce chances of depression and has several other health risks, some health risks, which may even lead back to a greater chance for depression.