The number of individuals in the United States with depression, who are using cannabis, has increased significantly from 2005 to 2016. A new study published in JAMA Network Open found that many of them are using daily or almost daily.
The researchers analyzed survey data to find out how many people with depression used cannabis over the previous month, as well as daily or near-daily.
A repeated cross-sectional study analyzed data from 16,216 adults aged 20 to 59 years. These adults had taken the National Health and Nutrition Examination Survey, an annual cross-sectional survey in the United States, between 2005 and 2016.
The researchers analyzed survey results to include participants who listed cannabis use, depression, or control variates. To mitigate bias, a post hoc analysis looked at time trends and associations between cannabis use and depression in a sample missing at least 1 control variate.
Past-month cannabis use increased from 12.24% in 2005 to 17.3% in 2016. This shows a significant change (OR, 1.09; 95% CI, 1.03-1.15; P < .001): the estimated odds of monthly cannabis use increased by about 9% every 2 years.
Daily or near-daily use increased even more, by about 12% every 2 years.
Researchers also found people with “probable” depression had a higher prevalence of past-month cannabis use compared to those without depression (ie, 2005-2006, 17.81% [SE, 3.77] vs 11.90% [SE, 1.18]; 2015-2016, 31.88% [SE, 2.89] vs 16.09% [SE, 1.90]. They also had higher rates of daily or near-daily use (e.g., 2005-2006, individuals with vs without depression, 7.03% [SE, 2.84] vs 3.59% [SE, 0.57]; 2015-2016, 15.59% [SE, 3.19] vs 5.27% [SE, 0.92]).
With past-month cannabis use being self-reported, limitations include the fact that participants may have underestimated their cannabis use. In addition, probable depression was evaluated for the past 2 weeks, while cannabis use was looked at for the past 30 days. It is therefore unclear whether depression existed prior to the 2-week period or whether cannabis use followed the onset of depression. That being said, the findings of different time trends in depression and cannabis use do not support the hypothesis that a higher proportion of individuals who use cannabis are at risk for developing depression.
Previous studies have associated cannabis use with worsening depressive symptoms. However, the media frequently airs cannabis campaigns. “While further research to understand the mechanisms underlying the increasingly strong association of depression and frequent cannabis use is needed, the study findings highlight a current need for information campaigns around cannabis and depressive disorders,” the researchers concluded.
Gorfinkel LR, Stohl M, Hasin D. Association of Depression With Past-Month Cannabis Use Among US Adults Aged 20 to 59 Years, 2005 to 2016. JAMA Netw Open [published August 3, 2020]. doi: 10.1001/jamanetworkopen.2020.13802