Objective: The objectives of this study are to: 1) determine the association between cannabis use and depressive symptoms; 2) quantify the association between cannabis use and intake of antidepressant medications; 3) look at the temporal trend of depressive symptoms and cannabis use in NHANES 2005-2012; and 4) determine the association between cannabis use and cardiovascular diseases.
Design: Cross-sectional study.
Data source: National Health and Nutrition Examination Survey (NHANES 2005–2012) which is conducted by the National Center for Health Statistics of the Centers for Disease Control and Prevention.
Study population: Participants of the NHANES (2005–2012) between 18-69 years of both genders. The total analytic sample was 20,150 adults.
Outcome: Depression (Patient Depression Questionnaire Score, PHQ9, = 10 versus PHQ-9 score < 10)
Methods: We applied NHANES weights to account for complex survey design. To deal with missing observations, we imputed the data using multivariate imputed chained equation. Logistic regression models were generated to get the adjusted odds ratios of the association between cannabis use and depressive symptoms, intake of antidepressant medications, and cardiovascular diseases. We also calculated the weighted prevalence of cannabis use and depressive symptoms.
Results: The odds of depressive symptoms are 1.8 (95% CI =1.36 -2.34) and 1.05 (95% CI=0.06-1.36) among regular cannabis female and male users, compared to non-users or non-regular users, respectively. The odds of depressive symptoms (in both genders) among those who smoked two to five joints and six or more joints per day are 1.23 (95% CI=1.07-4.2) and 2.21 (95% CI=1.07- 4.2), respectively, compared to those who use one joint per day. Quitting cannabis for more than a month is associated with less odds of depressive symptoms. The odds of depressive symptoms decreased by 54% (95% CI=0.27 - 0.82) and 32% (95% CI=0.31 - 1.07), among women and men respectively, for those who quit cannabis for = one month compared to those who quit for less than one month. The logistic model shows that there was no significant association between cannabis use and intake of antidepressants. The odds of regular cannabis use is 0.81 among women receiving antidepressants, compared to those not receiving antidepressants (95% CI=0.21- 3.1).The odds of regular cannabis use is 1.87 among men receiving antidepressants, compared to those not receiving antidepressants (95% CI=0.44 -7.9). The prevalence of depressive symptoms among women is 6.7%, 10.1%, 9.7%, and 9.4% in NHANES cycles 2005-2006, 2007-2008, 2009-2010, and 2011-2012, respectively. The prevalence of depressive symptoms among men is 5.1%, 7.1%, 7%, and 6.8% in cycles 2005-2006, 2007-2008, 2009-2010, and 2011-2012, respectively. The prevalence of regular cannabis use among women is 17% 15.5% 19.9%20.7%, in cycles 2005-2006, 2007-2008, 2009-2010, and 2011-2012, respectively. The prevalence of regular cannabis use among men is 24.2%, 23.3%, 27.1%, 27.5% in cycles 2005-2006, 2007-2008, 2009-2010, and 2011-2012, respectively. We did not find a significant association between cannabis use (even heavy use) and cardiovascular diseases (OR=1.07 & 95% CI=0.82-1.40)
Conclusions: Cannabis use is associated with higher depressive symptoms, particularly among women. Quitting cannabis for more than a month is associated with lower depressive symptoms, particularly among women. We did not find an association between cannabis use and intake of antidepressants which suggests that depression treatment might help to decrease use of cannabis. Cannabis use prevalence dropped in 2007-2008 cycle then rose again in the following cycles, which is an alarming finding. The prevalence of depressive symptoms increased in 2007-2008 cycles then dropped slightly in the following cycles. Our analysis did not reveal an association between cannabis use and cardiovascular diseases.