In relation to depression and anxiety, a higher incidence of depression and anxiety is usually the norm among long-term users of cannabis, although this could be due to other confounding and comorbid factors. For example, as reviewed in [128], in major depressive disorder (MDD) and bipolar disorder (BD), evidence generally reveals a harmful outcome of long-term cannabis use. Cannabis use was correlated with a higher risk of MDD diagnosis, and earlier onset of cannabis use was correlated with shorter time to MDD diagnosis [128,150]. This positive correlation between long-term cannabis use and depression or anxiety seems to be a consistent finding, although some other studies indicate this correlation disappears when controlling for multiple confounding factors, such as the co-use of other drugs, sex, age, genetic traits and education level, among others [128,151,152,153]. Similarly, evidence indicates the harmful effects of long-term cannabis use in bipolar disorder (BD), with frequent cannabis use being associated with heightened risk of BD onset [154] and/or exacerbation of BD symptomology [154,155,156]. It is worth noting that these effects of long-time use of cannabis are in opposition
