Using data of the ongoing National Longitudinal Survey of Youth of 1979 researchers of the Johns Hopkins University in Baltimore investigated the influence of cannabis use on the development of depression. A total of 8,759 adults (age range 29-37 years) interviewed in 1994 had complete data on past- year cannabis use and current depression. The risk for depression was significantly increased by 1.4 in cannabis users in comparison to the non-using group. However, after adjustment for possible influencing factors the risk was no longer increased in the cannabis group. (Source: Harder VS, et al. Addiction 2006;101(10):1463-72.)