By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - You may have heard about the recent study that took a look at the link between soda, coffee and depression. Any study that looks at coffee and soda gets attention and here I am talking about it.  

Over 200,000 people were studied and it was found that those who drank four or more cups of soda per day had a greater risk of depression than those who did not drink soda. They also found that coffee drinkers were 10% less likely to be depressed.  

The research was based on following people for ten years.  

The problem is that the study is one of association not one of direct cause.  This means that researchers found some sort of link but not a cause. These types of studies are usually best for creating interest to look at new studies.