Depressingly stupid study on soft drinks and depression

  • by: |
  • 01/10/2013
We have entered the silly season of so-called science-based claims quite early this year.   I was going to write about the hysterical claims of some on the right that the media is overlooking the "role" of psychopharmacological drugs in 'causing' the Newtown tragedy but I'll save that for another time.  

Rather, I would reluctantly call attention to the media's portrayal and premature release of a study claiming a statistical association between soft drinks and depression.  I could only find an abstract and here it is:

Abstract Title: Sweetened beverages, coffee and tea in relation to depression among older US adults

Press Release Title: Hold the Diet Soda? Sweetened Drinks Linked to Depression, Coffee May Lower Risk

Objective: To prospectively evaluate consumptions of sweetened beverages, coffee and tea in relation to
depression among older US adults.

Author(s): Honglei Chen, MD, PhD, Xuguang Guo, Yikyung Park, Neal D. Freedman, Rashmi Shinha,
Albert Hollenbeck and Aaron Blair

Background: Sweetened beverages, coffee and tea are commonly consumed worldwide and have important
physical and mental health consequences.We prospectively evaluated consumptions of these beverages, in relation to depression
among 263,925 older US adults. Beverage consumptions were assessed in 1995-1996, and 11,311 depression
diagnoses since 2000 were self-reported in 2004-2006. Odds ratios (OR) and 95% confidence intervals (CI)
were derived from multivariate logistic regressions.

Results: Drinking sweetened beverages was associated with higher depression risk, whereas coffee drinking
was weakly related to lower risk. The OR and 95% CI comparing ≥4 cans/cups per day with none were 1.30
(1.17–1.44) for soft drinks, 1.38 (1.15-1.65) for fruit punches and 0.91 (0.84-0.98) for coffee (all P for trend <
0.0001). Further analysis seemed to suggest stronger associations with diet drinks than with regular. The ORs
between extreme categories were 1.31 (1.16-1.47) for diet versus 1.22 (1.03-1.45) for regular soft drinks, 1.51
(1.18-1.92) for diet versus 1.08 (0.79-1.46) for regular fruit punches and 1.25 (1.10-1.41) for diet versus 0.94
(0.83-1.08) for regular iced tea. Consistently, constituent-based analyses showed higher depression risk with
aspartame intake [ORs between extreme quintiles: 1.36 (1.29-1.44)], and lower risk with caffeine intake
[corresponding OR 0.83 (0.78-0.89)].

Conclusions: This large prospective study suggests that frequent consumption of diet sweetened beverages
may increase depression risk among older adults, whereas coffee consumption may lower the risk.

So let's set aside the methodological problems (no regular follow up of consumption, depression or other health conditions associated with depression such as diabetes or heart disease, surgical procedures associated with depression)  as well as the fact there is no clear definition of what kind of depression (major depressive, mild or bipolar).   The geniuses behind this study claim the odds ratio for a self report of depression ranged from 1.31 for soda drinkers (whether diet or sugar) to .083 for people drinking coffee.  

The problem is two fold:

1.  The lifetime odds ratio for people ages 45-65 being diagnosed with major depressive disorder at any time in life is 2.0 and for age 65 and over it is 1.0.   So that means that risk for depression for older people drinking soda actually was less than the general population.  

2.  The hazard ratio for age of onset declines at age 45, spike at age 50, declines again until age 65.   So it's likely, absent controlling for other conditions and demographics that the 'depression-soft drink' association is only mirroring the hazard rate.  

Finally, there are several other conditions and demographic elements that are several times more likely to be associated with major depression.  

You can get more information about the real risk of major depression and it's possible risk factors here:  

That is unless you have already made up your mind.  For those of you that have you might want to know that the same lead author found that smoking was associated with a decline in risk for Parkinson's.


Center for Medicine in the Public Interest is a nonprofit, non-partisan organization promoting innovative solutions that advance medical progress, reduce health disparities, extend life and make health care more affordable, preventive and patient-centered. CMPI also provides the public, policymakers and the media a reliable source of independent scientific analysis on issues ranging from personalized medicine, food and drug safety, health care reform and comparative effectiveness.

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