Down and High: Reflections Regarding Depression and Cannabis.

Catherine Langlois,Stéphane Potvin,Smadar Valérie Tourjman,Atul Khullar

doi:10.3389/fpsyt.2021.625158

Abstract

In light of the recent changes in the legal status of cannabis in Canada, the understanding of the potential impact of the use of cannabis by individuals suffering from depression is increasingly considered as being important. It is fundamental that we look into the existing literature to examine the influence of cannabis on psychiatric conditions, including mood disorders. In this article, we will explore the relationship that exists between depression and cannabis. We will examine the impact of cannabis on the onset and course of depression, and its treatment. We have undertaken a wide-ranging review of the literature in order to address these questions. The evidence from longitudinal studies suggest that there is a bidirectional relationship between cannabis use and depression, such that cannabis use increases the risk for depression and vice-versa. This risk is possibly higher in heavy users having initiated their consumption in early adolescence. Clinical evidence also suggests that cannabis use is associated with a worse prognosis in individuals with major depressive disorder. The link with suicide remains controversial. Moreover, there is insufficient data to determine the impact of cannabis use on cognition in individuals with major depression disorder. Preliminary evidence suggesting that the endogenous cannabinoid system is involved in the pathophysiology of depression. This will need to be confirmed in future positron emission tomography studies. Randomized controlled trials are needed to investigate the potential efficacy of motivational interviewing and/or cognitive behavioral therapy for the treatment of cannabis use disorder in individuals with major depressive major disorder. Finally, although there is preclinical evidence suggesting that cannabidiol has antidepressant properties, randomized controlled trials will need to properly investigate this possibility in humans.

Highlights

Depression is a leading cause of disability in the world [1, 2] with a lifetime prevalence in the general population of about 15% [3]
This review found changes in brain activity in chronic users of cannabis, attributions are complicated by comorbidities, a lack of information regarding the degree of use of cannabis and the varying tasks used during functional imaging
cannabis use (CU), in particular of cannabis products higher in THC content, is likely to be associated with increased adverse psychiatric effects, including depression

Summary

INTRODUCTION

Depression is a leading cause of disability in the world [1, 2] with a lifetime prevalence in the general population of about 15% [3]. Some studies show that a reduction in CU and cannabis abstinence are associated with improvements in anxiety, depression and functioning in individuals with problematic CU [14, 94] As such, these observations are consistent with the idea that mood symptoms may be secondary (not antecedent) to CU. Long-term treatment with antidepressants and ECT decreases basal stress-induced hypothalamic pituitary adrenal axis (HPA) activation, and increases levels of BDNF as well as neurogenesis [33] This body of evidence suggests that cannabis could have a therapeutic effect on depression. As discussed in this article, there is evidence linking THC with worsening of the symptoms of depression, and a suggestion that CBD may be associated with favorable effects when used to treat depression This information can be used to steer patients with depression away from the use of high THC content cannabinoid products, during adolescence.

LIMITATIONS

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CONCLUSIONS