Drinking sweetened beverages — either sugar-sweetened or diet — may be linked with a slightly higher depression risk, while drinking coffee may slightly lower the risk.
That is the finding from a new study to be presented in March at the 65th annual meeting of the American Academy of Neurology in San Diego.
In the study, people who drank sweetened beverages — including regular and diet sodas, fruit punch, and sweetened iced tea — had a higher risk for depression.
Researchers say the findings suggest that cutting down on sweetened drinks or replacing them entirely with non-sweetened beverages may help lower depression risk.
STOP RIGHT THERE. You just got a citation issued by the Science Police.
This study showed correlation, not causation. Did they really say that the beverages CAUSED depression. That’s a leap. Here is an analysis of the study.
To come to the findings, the researchers combined old data with new. They began by examining a survey originally conducted in 1995 and 1996 in which adults between the ages of 50 and 71 recorded their daily soda, tea, fruit punch and coffee consumption. Then, for this study, they returned to the same survey participants more than a decade later and asked if they had been diagnosed with depression in the years since 2000.
They found that those who drank four or more cans of sweetened drinks (whether soda, diet soda or fruit punch) had a significantly higher chance of being among the 11,311 study participants who were later diagnosed with clinical depression that those who didn’t. For sodas as a whole, there was a 30 percent greater chance of depression, but diet sodas carried a further 22 percent increase as compared to regular ones. Interestingly, regular coffee consumption was associated with a 10 percent lower chance of depression.
Does this mean you should stop drinking diet Coke and starting chugging coffee immediately? Probably not. This type of suggested link between two seemingly unrelated factors is an ideal time to bring up the difference between causation and correlation.
“With this, therefore because of this” is a logical fallacy. Lots of factors go up and down in tandem. As this piece notes, a simpler explanation (since sweetened beverages have no mechanism known to cause depression) is that those who like to drink a lot of diet soda may be at risk for some other reason of developing depression. On the other hand, people who like to drink a lot of coffee may be the opposite. It doesn’t mean everyone, it doesn’t mean products are bad or good for you. It means this science piece was written and hyped very poorly and leaves people prone to misunderstanding.
UPDATE (Jan. 09 2013):
Experts respond to the study.