Not only are individuals with depression at significantly higher risk for cannabis use compared with those without depression, this trend has increased dramatically over the last decade, new research shows.
Investigators analyzed data from more than 16,000 US adults between the ages of 20 and 59 years and found that those with depression had almost twice the odds of any past-month cannabis use compared with those without depression. Odds rose from 1.5 in the 2005-2006 period to 2.3 in the 2015-2016 period.
Moreover, the odds ratio (OR) for daily or near-daily use almost tripled for those with vs without depression between the two periods.
“Clinicians should screen their depressed patients for cannabis use, since this is becoming more common and could actually make their depressive symptoms worse rather than better,” senior author Deborah Hasin, PhD, professor of epidemiology, Columbia University Irving Medical Center, New York City, told Medscape Medical News.
The results were published online August 18 in JAMA Network Open.
“Cannabis use is increasing in the US and the potency of cannabis products is increasing as well,” Hasin said.
“Misleading media information and advertising suggests that cannabis is a good treatment for depression, although studies show that cannabis use may actually worsen depression symptoms, [so] we were interested in whether US adults were increasingly likely to be cannabis users if they were depressed,” she reported.
To investigate, the researchers assessed data from the National Health and Nutrition Examination Survey (NHANES), with a final study sample consisting of 16,216 US adults. The mean age was 39.12 years, 48.9% were men, 66.4% were non-Hispanic white, 65.6% had at least some college education, and 62.4% had an annual family income of less than $75,000.
Of these participants, 7.5% had “probable depression,” based on the Patient Health Questionnaire-9, the investigators report.
Past-month cannabis use was defined as using cannabis at least once during the past 20 days. Daily or near-daily past-month use was defined as using cannabis at least 20 times in the past 30 days.
Covariates included age, gender, race, education, marital status, annual family income, and past-year use of other substances, such as alcohol, heroin, and methamphetamine.
The researchers note that because the NHANES data were divided into six survey years (2005-2006, 2007-2008, 2009-2010, 2011-2012, 2013-2014, and 2015-2016), their analysis was based on a “new sample weight” that combined the datasets.
Results showed that the prevalence of any past-month cannabis use in the overall sample group increased from 12.2% in the 2005-2006 period to 17.3% in the 2015-2016 period (P < .001).
The investigators characterized this change as “significant,” adding that the estimated odds of cannabis use increased by approximately 9% between every 2-year time period.
The change was even more dramatic when the increase was examined across survey time periods (OR, 1.12; P < .001). The estimated odds of daily or near-daily use increased by approximately 12% between every 2-year period.
Interestingly, however, there were no significant changes in odds for depression when consecutive survey years were compared.
When the researchers specifically focused on the association between any past-month cannabis use and depression vs no depression, they found an adjusted OR (aOR) of 1.90 (95% CI, 1.62 – 2.12; P < .001).
Individuals with depression also had 2.29 (95% CI, 1.80 – 2.92) times the odds for daily or near-daily cannabis use compared with those without depression.
A post-hoc analysis looked at time trends in a sample group that included those missing information on at least one covariate (n = 17,724 participants). It showed similar results to those in the final sample that included no missing data.
People with depression have increased risk of using “most substances that can be abused,” Hasin said. “However, with the overall rates of cannabis use increasing in the general population, this is becoming especially pronounced for cannabis.”
Commenting on the findings for Medscape Medical News, Deepak D’Souza, MD, professor of psychiatry, Yale University School of Medicine, New Haven, Connecticut, said there is “concern about the unsubstantiated claims of cannabis having a beneficial effect in psychiatric disorders, the most common being depression.”
D’Souza, who was not involved with the study, called it “yet another piece of evidence suggesting that over the period of time during which cannabis laws have been liberalized, rates of past-month and daily cannabis use have increased, whereas rates of other substances, including alcohol, have remained stable.”
He suggested that a common limitation of epidemiological studies is that it is difficult to tell the direction of the association, “and it could be bidirectional.”
Nevertheless, there are clear implications for the practicing clinician, he added.
“If people have a history of depression, one should ask patients about the use of cannabis and also remind them about potential psychiatric negative effects of use,” D’Souza noted.
For the general public, “the point is that there is no good evidence to support cannabis use in depression treatment and, in fact, people with depression might be more likely to use it in problematic way,” he said.
Hasin agreed that it is “certainly possible that the relationship between cannabis use and depression is bidirectional, but the mechanism of this association requires more study.”
The study was supported by a grant from the National Institute on Drug Abuse to Hasin and by the New York State Psychiatric Institute. The study authors and D’Souza have disclosed no relevant financial relationships.
JAMA Netw Open. 2020;3:e2013802. Full article