The study, conducted by researchers in conjunction with the National Institutes of Health, found a correlation among people who consumed four or more cans of sweetened drinks per day, Smithsonian magazine reports. Among the more than 230,000 people studied, those who consumed that much soda showed a 30% higher rate of clinical depression than those who did not.
The numbers are worse for those who drink diet soda. There’s a 22% greater incidence of depression for those users above the already increased risk for soda drinkers in general, according to the study. Coffee drinkers, on the other hand, showed a 10% lessened incidence of clinical depression in the study.
The study was led by Dr. Honglei Chen using data from 1995 and 1996 and updated with a follow-up survey. Dr. Chen and his colleagues will be presenting their full findings in March at the annual meeting of the American Academy of Neurology.