Exercise as an adjunctive treatment for cannabis use disorder

Abstract

Background: Despite cannabis being the most widely used illicit substance in the United States, individuals diagnosed with cannabis use disorder (CUD) have few well-researched, affordable treatment options available to them. Although found to be effective for improving treatment outcomes in other drug populations, exercise is an affordable and highly accessible treatment approach that has not been routinely investigated in cannabis users.

Objectives: The aim of this paper is to inform the topic regarding exercise's potential as an adjunctive treatment for individuals with CUD.

Methods: We reviewed the evidence surrounding cannabis use and its current treatment in the United States, explored the rationale for including exercise in the treatment of substance use disorders (SUDs), and in particular, proposed a biological mechanism (i.e., endocannabinoids (eCBs)) that should be examined when utilizing exercise for the treatment of CUD.

Results: Cannabis use is widespread and increasing in the United States. Chronic, heavy cannabis use may dysregulate the endogenous cannabinoid system, which has implications for several psychobiological processes that interact with the eCB system such as reward processing and the stress response. Given that exercise is a potent activator of the eCB system, it is mechanistically plausible that exercise could be an optimal method to supplement cessation efforts by reducing psychophysical withdrawal, managing stress, and attenuating drug cravings.

Conclusion: We suggest there is a strong behavioral and physiological rationale to design studies which specifically assess the efficacy of exercise, in combination with other therapies, in treating CUD. Moreover, it will be especially important to include the investigation of psychobiological mechanisms (e.g., eCBs, hippocampal volume), which have been associated with both exercise and SUDs, to examine the broader impact of exercise on behavioral and physiological responses to treatment.

Keywords: Exercise; anandamide; cannabis use disorder; endocannabinoid; treatment.

Figure 1. Schematic of the relationships between the endocannabinoid system, chronic cannabis use, and exercise

It is proposed that chronic, heavy cannabis use dysregulates the endocannabinoid (eCB) system, which is highlighted by a downregulation of CB1 receptors (CB1r) in several brain regions including the hippocampus, substantia nigra, and ventral striatum, which are regions implicated in reward and stress processing. Changes in eCB physiology as a result of cannabis use could contribute to psychological outcomes including heightened anxiety, depression, stress reactivity, and craving. Conversely, acute exercise in humans has been shown to increase circulating levels of anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and chronic exercise in animals has been found to upregulate CB1 receptors, most notably in the hippocampus. ECB changes have been associated with beneficial psychological outcomes including reductions in anxiety and increases in positive affect. Exercise has also been shown to relieve anxiety, depression, and craving in a variety of substance use populations. More research needs to be conducted to further develop these proposed relationships.