A recent study presented at a the American Academy of Neurology meeting found that over the course of 10 years, people who drank more than four cups or cans of soda a day were 30% more likely to develop depression than those who steered clear of sugary drinks. The correlation held true for both regular and diet drinks, but researchers were sure to note that the risk appeared to be greater for those who primarily drank diet sodas and fruit punches. Although this type of study can't prove cause and effect, its findings are worth considering.