Cannabinoids and Mental Health, Part 1 : The Endocannabinoid System and Exogenous Cannabinoids, Andrew Penn, 2019

Cannabinoids and Mental Health, Part 1 : The Endocannabinoid System and Exogenous Cannabinoids

Andrew Penn

Journal of Psychosocial Nursing and Mental Health Services, 2019, 57, 9, 7-10.

Doi : 10.3928/02793695-20190813-01



The increasing public acceptance of cannabis and the proliferation of cannabis products in the market-place has coincided with more patients using the drug as a substitute for psychiatric medications or as an adjunctive treatment modality for psychiatric conditions, despite limited evidence of efficacy. With a goal of furthering harm-reduction eff orts in psychiatric nursing, the current article reviews the fundamentals of the endocannabinoid system in humans and the exogenous phytocannabinoids that act on this regulatory neurotransmitter system. The basics of cannabis botany are also reviewed to help nurse clinicians understand the heterogeneous nature of cannabis products. This foundational knowledge will help improve clinical interactions with patients who use cannabis and provide the necessary understanding of cannabinoids needed to undertake further scientific query into their purported benefits in psychiatric disease states. [Journal of Psychosocial Nursing and Mental Health Services, 57(9), 7-10.]


Psychosocial nursing has, at its core, a belief in meeting patients “where they are.” This tradition of partnership requires understanding of the ecosystem in which both the person and a behavior reside. Regarding the phenomenon of substance use, the context in which the use occurs and the substance itself and how it interacts with the body must be understood.

Regarding cannabis, most nurses have not received suffi cient education about this plant to meet patients who use it where they are. Depending on one’s generation, cannabis was a semi-innocuous presence in the youth culture of the 1960s and 1970s; a mindwrecking drug that one was told to “Just Say No” to by Nancy Reagan; or a vague panacea for all manner of ills in an anecdotally based pseudo-medicalized/ semi-legalized environment. Few nurses receive formal training on the endocannabinoid system of the body or the effect of exogenous cannabinoids, both for good and for ill. Dispensary “budtenders” know more than most clinicians about cannabis.

The intention of this two-part article series is not to discuss cannabis as a drug of abuse, but rather to help nurses understand the endocannabinoid system, the exogenous cannabinoids 9-Tetrahydro-cannabinol (THC) and cannabidiol (CBD), the existing evidence for cannabinoid use in psychiatry, the gaps in existing studies, and how to best guide patients who are already using cannabinoids or are interested in adding them to their psychopharmaceutic regimens. This article reviews the endocannabinoid system of the body and the basic botany of the cannabis plant. The next article will discuss the mechanism of exogenous cannabinoid CBD, its risks, and the evidence for its use in psychiatric practice.


Research into the benefits of cannabinoids has historically been thin, in part because of the challenges of
studying the benefits of a Schedule I drug (as opposed to studying harm, which has been funded through the National Institute of Drug Abuse). At the same time, there is a rising cannabis industry, intent on selling a product, that makes intimations of health claims for cannabis that are not subject to the same scrutiny or legislation as that of U.S. Food and Drug Administration (FDA)–approved medications. To the cannabis industry, anecdotal evidence is suffi cient, and many patients have had confi rmatory
experiences of these claims of benefi t from cannabis. As such, the experiences of patients often far surpass the accreted knowledge of the scientifi c literature, leaving clinicians struggling to know how to advise patients. Many clinicians have taken an absolute stance: that cannabis cannot be helpful.
With this, I disagree. Although certain components of cannabis, in certain populations (e.g., THC in patients susceptible to psychosis), can be harmful, there are also many candidate indications for cannabinoids that have yet to be rigorously studied by controlled studies. Until such studies are performed, it is impossible to know if the claims are true or panacea. However, I would encourage that we as clinicians remain open minded and view these anecdotes as seeds of hypotheses for further investigation. The cannabis industry is unlikely to take these studies on themselves. Therefore, it is incumbent on the scientifi c community to take inquiry into the benefits of cannabinoids. I encourage
clinicians to take patients’ interest in cannabinoids seriously by engaging them in conversations of the benefits and risks of cannabinoids, being honest about what we do and do not know, as the best way to reduce harm.