Casual cannabis use: Is there a link to depression?

 In 2014, recreational cannabis use was legalized in Colorado, and seven other states have since followed suit. With an ever-expanding part of the population using marijuana to cure a number of ailments, researchers at Colorado State University have investigated its effects on mood.

The researchers - led by Lucy Troup, assistant professor in the university's Department of Psychology - publish their findings in the journal PeerJ.

They note that the "relationship between cannabis use and symptomatology of mood and anxiety disorders is complex," adding that although "a great deal of research exists and continues to grow, the evidence remains contradictory."

Troup and colleagues point to a large international survey published in 2013, in which 5.2 percent of respondents reported that they used cannabis to alleviate depressive symptoms.

Meanwhile, a survey of medical marijuana users in California revealed that 26.1 percent of participants reported therapeutic benefits for depression, and 37.8 percent reported benefits for anxiety.

"This trend of self-medication for conditions other than the one prescribed is too large to ignore when investigating the associations between cannabis use and mood disorders," write the Colorado State University researchers.

They add that this increases "the need to include recreational users for research, especially when the casual user group are most likely recreational users and seem to sustain the greatest deficits in mood."

Interestingly, the participants who were categorized with subclinical depression, and who also used cannabis to treat their depressive symptoms, scored lower on anxiety symptoms than on their depressive symptoms. In short, they were more depressed than anxious.