A study led by Valerie S. Harder, Andrew R. Morral, & Jeremy Arkes at Johns Hopkins University in Baltimore was conducted to see whether marijuana use could cause depression. The study conducted an interview of 8759 men and women between the age of 29 and 37 years and had complete data on marijuana use and current depression. The study concluded that among past year marijuana user had 1.4 odds of developing depression compared to the non-using control group. An adjustment of the data further showed that marijuana users had only a 1.1 times higher odds of depression than the control. The study concluded that past year use of marijuana will not predict later development of depression.
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