O Cannabis

In a vanguard move towards cognitive liberty, Canada has finally rescinded its general prohibition on recreational cannabis. On October 17th 2018, cannabis will be legal under The Cannabis Act, which controls its production, distribution, sale and possession across Canada. While many questions remain about how cannabis will be functionally integrated into mainstream culture, it’s worth taking some time to appreciate what we do know about its psychoactive properties and its complex relationship with mental health. Decades of mis- and disinformation have muddied the waters about both the risks and benefits of cannabis use, and it can be hard to overcome some of the implicit biases that we’ve internalized about this plant. However when we look ahead to how legalization will play out, I believe a genuine and cautious optimism is warranted. So what are some of the actual risks and benefits? Before we explore some of the big ones, let’s first take a step back to appreciate that the effects of any psychoactive drug are dependent on three important factors: dose, set, and setting.

Dose of course refers to how much of the substance has been ingested. While that seems straightforward enough, with cannabis it becomes complicated by the fact that it contains over a hundred different cannabinoids, the chemicals that have psychoactive effects. The most abundant and most frequently discussed are THC and CBD, but many more exist in differing quantities depending on the plant strain. They all primarily influence two types of protein receptors (called CB1 and CB2) found on neurons and other cells throughout the brain and immune system, but they each do so to different degrees. This means that the effects of cannabis largely have to do with the ratios of these various cannabinoids and with the local availability of receptors, which can temporarily change with chronic use. The route of administration also influences how much of and how fast these cannabinoids make it into circulation and into the brain. There are important differences in absorption rates between smoking, vaping, eating, and drinking cannabis products.

Set and setting can be thought of as the “who, when, and where” of the experience. Set includes all of the beliefs, expectations, personality traits, and genetics that the user brings to the experience. It also includes our physiological state, which is influenced by the time of day, our diet, mood, and social relationships. Setting is the set of environmental conditions in which the drug is consumed. This includes the location, timing (season, time of day), and people included in the experience. So between dose, set, and setting there is a huge range of experiences that can be generated, making it all the more difficult to pin down the general risks and benefits. But let’s give it a quick try anyway.

In the category of risks we have (in no particular order): the potential for abuse or addiction, the onset of hallucinatory or delusional psychosis, and general cognitive impairments. The problems of cannabis use disorder are either under- or overstated depending on the community discussing it, but the prevalence is about 9% among users. This compares favourably to alcohol and nicotine. The comparison is even more encouraging given that cannabis has far fewer negative physiological effects than other legal recreational drugs, and that it’s virtually impossible to truly overdose on it.

Another major concern that is often brought up is the potential for cannabis to induce psychosis. This fear turns out to be both under- and overstated by different groups as well. The risk is real, as a very small minority (~1%) of people who are already genetically predisposed to psychosis can have it triggered by cannabis use. However, rates of psychosis do not change geographically as a function of differing rates of cannabis use, and the onset of psychosis has not been demonstrated in first time adult users, so it’s likely that cannabis can change the timing but not the likelihood of developing psychosis.

Cognitive impairment is another concern, which includes effects such as slower reaction times, visuomotor coordination, and reduced working memory capacity. While these deficits are important to avoid during adolescence when the brain is still developing, for adults they appear to be temporary rather than permanent, and even long time chronic users will test normally on cognitive tests within days to weeks of full abstinence.

In the category of benefits we have (again in no particular order): pain relief, appetite and sleep regulation, sensory refinement, and mental flexibility or increased creativity. The pain relieving effects are interesting because cannabis doesn’t seem to dampen the sensation of pain so much as it decreases our emotional response to it. These processes involve different brain networks (sensory cortex vs. limbic circuits). So while the pain is still there, it can just be ignored much more easily. Appetite and sleep can be modulated by the effects that cannabinoids have on another brain structure – the hypothalamus.

Sensation and perception are also temporarily re-tuned by cannabis, changing the frequency range for sound and various dimensions of touch, taste, and smell that we’re most sensitive to. These perceptual changes can interact with similar changes in higher cognition to help generate thoughts and ideas that tend to be outside of the typical range of the sober mind. Many people report bouts of creativity while high, and the worlds of literature, art, and music, not to mention science and technology, would be much shallower pools without cannabis. Given all of this, it’s not a stretch to say that there are specific modes of thought and perception that are only achievable through consuming cannabis. Legalization therefore brings us closer to realizing the spirit of Section 2 of the Charter of Rights and Freedoms, specifically freedom of thought.

The risks and benefits of cannabis use described here are not exhaustive, and we’re approaching a renaissance for scientific research into its effects that will very quickly answer more questions about cannabis than have been attempted in the last half century. The intersection between cannabis and mental health is already immense, and the potential is even greater. It’s an exciting time for psychology in Canada.


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