Author(s): Michael Coover, Ives Hong, Mattison Hillin, Hallee Hassell, Andrew Shepard
Mentor(s): Dannelle Larsen-Rife
Institution UTech
The increasing legalization and medicinal use of cannabis have prompted significant research on its mental health effects. The National Survey on Drug Use and Health (NSDUH, 2023) reports historically high cannabis use in the U.S., with over 52 million users. This literature review synthesizes findings from 15 studies published between 2013 and 2022 to examine the bidirectional relationship between cannabis use, depression, and anxiety. These studies include 2 meta-analyses, 3 longitudinal studies, 4 cross-sectional studies, 2 experimental studies, and 4 observational designs. Key outcomes were influenced by factors such as age, strain, frequency, potency, methods of ingestion, and individual psychological and genetic characteristics. Since 2017, depression has been the leading cause of disability worldwide (World Health Organization, 2017) and is particularly prevalent among cannabis users, with nearly 20% of those affected using cannabis compared to 8.67% without depression (Pacek et al., 2019). Over 40% of cannabis users in the U.S. and Canada report using cannabis to alleviate depressive symptoms (Leung et al., 2022). Balanced strains of tetrahydrocannabinol (THC) and cannabidiol (CBD), the primary psychoactive and non-psychoactive compounds in cannabis, respectively, have demonstrated mood-elevating effects and moderate reductions in anxiety when used under medical supervision (Stoner, 2017; Martin et al., 2021; Onaemo et al., 2021). A longitudinal observational study of 2,300 patients prescribed THC and CBD-based oils reported significant reductions in anxiety and depression within two weeks of treatment, with benefits persisting over three months (Fogel et al., 2023). Conversely, frequent and high-potency cannabis use is associated with increased risks of depressive symptoms or major depressive disorder, and cannabis use disorder (CUD) (Levine et al., 2017; Lev-Ran et al., 2013). Anxiety and depression are prevalent among those with severe CUD, particularly those with psychological vulnerabilities, genetic predispositions, or who initiated cannabis use during adolescence. (Lawn et al., 2022; Murkar et al., 2022). During the COVID-19 pandemic, heavy cannabis use was linked to worsened mental health outcomes, including depression and anxiety. (Lowe et al., 2019). High-THC cannabis is also associated with dependency and higher risks of psychosis and schizophrenia (Di Forti et al., 2019). Given the complex bidirectional relationship between cannabis use, depression, and anxiety, healthcare providers should evaluate personalized treatment approaches when considering medical cannabis for patients with mental health disorders. Providers must weigh the potential benefits against risks, including alternative therapeutic options (Sarris et al., 2020).