Other than alcohol, marijuana (cannabis) is the most commonly used drug in the United States. Some 39 million Americans, 12% of the population, use marijuana at least occasionally. While clearly more commonly used by adolescents and young adults, in 2018 4% of adults over 65 admitted to using it within the prior 30 days.
In the United States, the use and possession of marijuana is illegal under federal law for any purpose, by way of the Controlled Substances Act of 1970. Under the CSA, cannabis is classified as a “Schedule I” substance, right up there with heroin and methamphetamine, determined to have a high potential for abuse and no accepted medical use – thereby prohibiting even medical use of the drug. At the state level, however, policies regarding the use of cannabis vary greatly, and in many states conflict significantly with federal law. As of 2020, medical use of marijuana is legal in 33 states and the District of Columbia, and recreational use is legal in 11 more states.
What are the benefits of marijuana? What are the harms? To a large degree, we simply do not know. Marijuana is not a single substance; the plant contains at least 500 chemical substances. The best known and studied are cannabidiol (CBD) which I wrote on recently and delta-9-tetrahydrocannabinol (THC). It is THC that has the CNS (brain) effects. Because of the federal classification of cannabis, much less research has been done than should be, and much of what you read is low quality. Many of the reputed benefits and harms arise from studying people who admit or deny use. Since use was until recently a criminal offense, self-reporting is likely to be unreliable. There is also the confounding factor of whether people who do or do not use marijuana are otherwise the same. Many of the studies claiming adverse effects on intellect are of this variety and not necessarily valid.
Another confounding factor is that the THC content of marijuana, at least that seized by the DEA, the federal Drug Enforcement Agency, has been going steadily and dramatically higher. In 1995, the average concentration of THC in seized products was 4%; in 2014 it was 12% - this is not the pot of the 1960’s!
The human brain has cannabinoid receptors, which mediate the psychoactive effects of cannabis. There are other receptors in immune cells and other tissues that may be more targeted by CBD. Acutely, the effect of THC is the “high:” euphoria, relaxation, altered sensations – and also: decreased processing speed, attention and reality testing. “Tolerance” develops quickly as the receptors are down regulated, so that daily use results in much less response.
Proven benefits of THC are limited. It has some benefit in preventing chemotherapy-related nausea and improves the appetite in many people with wasting disease such as AIDS. While it has been “approved” for pain relief in states where medical marijuana is legal, its benefits beyond those of prescription and OTC pain relievers are modest.
The headlines were dominated in August by a statement from the American Heart Association which stated that cannabis had no cardiovascular benefits but did have adverse CV effects, including arrhythmias and heart attacks. Critics noted that most of the adverse effects were anecdotes and case reports.
Inhaled marijuana products can have the same adverse effects as smoking any product. Before Covid-19, when vaping-relating lung disease was our biggest public health concern, it appeared that vaping cannabis products was particularly dangerous.
Bottom line? Cannabis is not a miracle drug. It is probably no worse than alcohol. (I have never heard of an angry belligerent pot user.) It can clearly impair your ability to safely drive or operate machinery. If you feel it helps your migraine or other painful condition, use it, but use it cautiously, as it is habit-forming.
Until we know more about its effects on the developing brain, I would actively discourage use by adolescents, as I do for alcohol.
More quality scientific study is needed and would be encouraged by moving cannabis out of Schedule I by the DEA.
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