by Dr. Mark Gold
Higher levels of stress are associated with an increased risk of substance use disorders (SUDs) and other mental health conditions like depression. Stress may exacerbate underlying conditions and weaken individual response systems that process events and build resilience. It can also make licit and illicit substance use more appealing as a treatment for anxiety. In popular culture and many ordinary associations, cannabis use is often presented as a stress-relieving substance, a mostly harmless escape from life’s ups and down. It’s also seen as an option for those just seeking to unwind. These urban myths are rarely evaluated in real time. Recent scientific research has not validated this self-medication approach to stress and anxiety. If anything, research suggests that such substance use is a major warning sign. The use of cannabis or other THC products may carry special risks for those self-medicating and shouldn’t be so lightheartedly rendered as a relaxation tool.
Use of THC products is widespread. Rates of cannabis smoking and vaping are similar to those reported for cigarettes and cigarette smoking is related to marijuana use. I have studied and written about these associations for many years: to summarize, both have important second and third hand exposure risks and it may well be that learning to smoke is the most important gateway event.(1) THC use is also rising in many states that have legalized the substance, and among the young, for whom the effects of THC are different and likely more dangerous than they are for older individuals. The NIH’s 2019 Monitoring the Future survey also found a spike in rates of youth vaping marijuana, concerning because of the substance and the risky delivery route.
But whether it’s logical to use THC products for stress relief, instead of exercising or meditating or taking a walk or doing yoga or talking to a friend or therapist, is a different question from why some individuals do it. People often report anxiety as a primary motivation for using THC products, and it isn’t hard to find someone who will swear by the substance as a tranquil godsend without which life would be far less interesting and considerably more fraught. In January, researchers published the results of a study on the manifestation of stress and anxiety in the brain. It provides one answer to the question of why some individuals turn to marijuana for stress relief—a molecule that manages anxiety and stress is involved in the same brain functions affected by marijuana. This study also suggests that stress is a risk factor that might make smoking more reinforcing.
What did this study find about stress management in the brain?
This study found that a molecule, called 2-AG, helps create and move stress-related chemicals in the brain. These chemicals move along a brain path that connects the amygdala, which handles emotion, to the prefrontal cortex, which helps us make decisions. When individuals experience more stress, this path between the amygdala and prefrontal cortex becomes more active. The molecule works to manage stress and anxiety by limiting the chemicals that pass through the connecting path. 2-AG is part of the brain’s anxiety-managing endocannabinoid system, in which the effects of marijuana are also felt. The brain’s anxiety-limiting molecule and marijuana operate through the same receptors.
In this study, researchers made mice stressed through exposure to foot shocks and bad odors. Then they observed the mice’s brains and behavior to measure the effects of 2-AG and the path connecting the amygdala and prefrontal cortex. They found that making the mice stressed curbed the effects of the molecule’s ability to limit anxiety and led to more activity in the connecting path as the mice behaved more anxiously. The findings indicate that larger levels of stress interfere with 2-AG’s effects on blocking anxiety, overwhelming the endocannabinoid system and allowing anxiety-related chemicals to speed through the brain.
Why is this important?
Cannabis use has been suggested as a treatment for pain and also the opioid crisis. Both false claims have been refuted. Cannabis does appear to have many advocates who argue that it is as good as any medication or therapy for anxiety and stress. This is also not true. This study finds specific pathways in the brain that lead to anxiety—especially the impairment of 2-AG—and suggests that medications could be developed to boost this molecule and limit anxiety. These discoveries help us understand the neurological basis for feelings of anxiety and this by itself is important. It could lead to the development of more effective anti-anxiety medication. It might also appeal to individuals who use THC products, or other substances, to manage stress. The authors of this study hope to do more research on how the cannabinoid system becomes impaired after stress exposure, how it repairs its anxiety-limiting function after impairment, and which molecules are involved in these processes. And this study may also suggest that well-functioning cannabinoid systems somehow maintaining their anxiety-limiting effects in the brain could be the reason why some individuals exposed to trauma don’t develop serious mental health conditions. The results also refer to stressed-out mice, not humans, and will need to be validated before extrapolations of the data make sense of our stress and exposure to trauma.
As Harvard’s Kevin Hill has said recently, “Medical cannabis may ultimately prove to be effective in treating many other medical conditions, including posttraumatic stress disorder and Tourette syndrome, but as yet, there is little evidence to show that this is the case”.3 Developing better tools to manage stress and anxiety makes the most sense. Developing better coping mechanisms is likely to be especially beneficial for individuals using risky substances. Research continues to suggest that marijuana is one of these risky substances. The risks of THC vaping are largely unknown but the news is not good: what we know so far is more of a work in progress.4 Many substances without overdose risk are considered safe because we do not think of the many ways that they can be dangerous. Of course, smoking exposes everyone to second hand and third hand smoke. That is a big problem.
Driving is another emerging problem. Traffic accidents are increasing in cities and states where cannabis is legal and widely used. A recent study found that individuals using cannabis are worse drivers. They have poor overall driving ability, even when they are not under the influence.5 Impaired driving ability in tested simulations included crossing the center line, speeding, hitting pedestrians, and missing stop signs. Study participants who started using cannabis before the age of 16 fared even worse. And other research has found an association between cannabis legalization and cannabis use disorder, based on National Survey on Drug Use and Health (NSDUH) data from 2008-2016.6 An editorial on this study notes, “Increases in cannabis use among adults of legal age were observed, but these should not be surprising because at least part of the rationale for creating regulated commercial markets for cannabis is to provide access for adults who choose to use it.” We might wonder about the desirability of this rationale given distressing findings about the effects of cannabis use, but discovering more effective ways to manage anxiety could hopefully help some individuals avoid these pitfalls.
References:
Tullis, L.M., Dupont, R., Frost-Pineda, K., Gold, M.S. (2008). Marijuana and Tobacco, A Major Connection? Journal of Addictive Diseases, 22, 51-62. doi: https://doi.org/10.1300/J069v22n03_05
National Institute on Drug Abuse (NIDA). (2019). Vaping of marijuana on the rise among teens [news release]. Retrieved from https://www.drugabuse.gov/news-events/news-releases/2019/12/vaping-marijuana-rise-among-teens
Hill, K.P. (2020). Medical Cannabis. JAMA, 323(6), 580. doi: 10.1001/jama.2019.17403
Qarajeh, R., Kitchen, J. (2019). THC Vaping-Induced Acute Respiratory Distress Syndrome. Am J Med, [Epub ahead of print]. doi: 10.1016/j.amjmed.2019.09.015.
Dahlgren, M.K., Sagar, K.A., Smith, R.T., Lambros, A.M., Kuppe, M.K., Gruber, S.A. (2020). Recreational cannabis use impairs driving performance in the absence of acute intoxication. Drug and Alcohol Dependence, available online 14 January 2020. doi: https://doi.org/10.1016/j.drugalcdep.2019.107771
Cerdá, M., et al. (2020) Association Between Recreational Marijuana Legalization in the United States and Changes in Marijuana Use and Cannabis Use Disorder From 2008 to 2016. JAMA Psychiatry, 77(2), 165-171. doi: 10.1001/jamapsychiatry.2019.3254
Citation:
1. Marcus, D.J., et al. (2020). Endocannabinoid Signaling Collapse Mediates Stress-Induced Amygdalo-Cortical Strengthening. Neuron, [Epub ahead of print]. doi: 10.1016/j.neuron.2019.12.024.
Dr. Mark S. Gold is a teacher of the year, translational researcher, author, mentor and inventor best known for his work on the brain systems underlying the effects of opiate drugs, cocaine and food. Read more by Dr. Gold here.