BACKGROUND: With the legalization of retail marijuana in 2014, the Colorado Department of Public Health and Environment (CDPHE) began monitoring marijuana use patterns and health effects and noted high rates of co-occurring marijuana and mental health diagnoses in data from Hospital Discharges and Emergency Department visits. Colorado's Behavioral Risk Factor Surveillance System (BRFSS) began collecting marijuana data in 2014, and estimated that from 2014-2015, 13.3% of adults 18 years and older used in the past month. Additionally, mental health disorders are prevalent in Colorado; in 2014-2015, 18.9% of adults had ever been diagnosed with a depressive disorder and 9.5% had experienced mental health distress ( ≥14 mentally unhealthy days in the past 30 days, which is associated with clinical depression). CDPHE examined the relationship between marijuana use and mental health using BRFSS.
METHODS: BRFSS is an annual statewide randomized telephone survey; responses are weighted to represent the state's population. In this analysis, self-reported, past-month marijuana exposure categories were: 0 days, 1-19 days, and 20-30 days of use. Two self-reported mental health outcomes were measured: lifetime diagnosis of a depressive disorder and mental health distress. Covariates assessed were age, gender, education, tobacco use, and alcohol use. Manual backwards stepwise, binary logistic regression was performed using complex survey procedures in SAS v. 9.3.
RESULTS: Marijuana use in the past month increased the odds of having had mental health distress, even after adjusting for gender, age, education, and current tobacco use (OR: 1.57, 95% CI: 1.21-2.04 in those who used 1-19 days vs. 0 days and 1.87, 95% CI: 1.39-2.52 in those who used 20-30 day vs. 0 days). Marijuana use also was associated with diagnosed depression, and gender was an effect modifier. Females who used 1-19 days had the highest odds of having a diagnosis compared to males who did not use in the past month (OR: 4.54, 95% CI: 3.23-6.38). Comparatively, males who used between 20-30 days had the lowest odds compared to the same reference (OR: 1.87; 95% CI: 1.35-2.57). Alcohol use was not a covariate.
CONCLUSIONS: These results suggest an association between self-reported marijuana use and current and lifetime self-reported mental health outcomes, which demonstrate the need to investigate the temporal relationship using a data source with that capability. Further analyses should also examine the role of healthcare access and other socio-economic status variables as potential covariates.