April 26, 2010 -- The more clinically depressed people become, the more chocolate they eat, a study has found.
People who tested positive for depression consumed about 60 percent more chocolate compared with people who had lower test scores. A depression score suggesting major depression more than doubled chocolate consumption, investigators reported in the April 26 issue of Archives of Internal Medicine.
The association held up for both men and women and appeared unaffected by other dietary factors. But whether the findings meant that depressed people may eat more chocolate -- or more chocolate may make people depressed -- is still unclear.
"Whether there is a causal connection, and if so in which direction, is a matter for future prospective study," Dr. Natalie Rose of the University of California, Davis, and colleagues wrote in conclusion.
Cultural traditions have long associated chocolate with mood benefits, as reflected in almost 6 million results the authors retrieved in a Google search of "chocolate" and "mood."
One 2007 study in the British Journal of Psychiatry showed that half of 3,000 people with depression said that chocolate actually made them feel better.
In general, however, associations between chocolate and mood have attracted little scientific interest, Rose and coauthors wrote. The scant published information on the issue has come from studies that had design flaws that limited interpretation of the results.
To improve the quantity and quality of data, the authors examined the relationship between chocolate consumption and mood in 931 men and women who participated in a clinical study of cholesterol control. The questionnaire used in the study included an item about chocolate consumption. Additionally, participants completed a food frequency questionnaire, and investigators assessed the depression level of participants.
Investigators compared chocolate consumption in study participants with lower versus higher scores for depression. The results showed that participants who tested positive for depression consumed an average of 8.4 servings of chocolate per month compared with 5.4 servings among participants with lower scores. Participants with the highest depression scores consumed an average of 11.8 servings of chocolate per month.
"In contrast to the findings for chocolate, differences in consumption of fat, energy, or carbohydrates by [depression score] group were not significant, suggesting relative specificity of the chocolate finding," the authors wrote.
Rose and coauthors suggested several mechanistic explanations for the observed association between chocolate consumption and depression score:
* Stimulation of self-treatment or self-medication with chocolate
* Stimulation of chocolate craving for reasons unrelated to depression
* Chocolate may drive depressive symptoms, rather than vice versa
* Inflammation or other physiologic factors might drive chocolate craving and depression