Long Term Liability if Cannabis Rots Our Brains

This is your brain on drugs. Let it go...
This is your brain on drugs. Let it go…

It all starts with correlation. In 1950, the British Medical Journal published an article showing a high correlation between lung cancer and smoking tobacco. In 1998, the tobacco industry entered a settlement agreement with the attorneys general of 46 states, agreeing to change its marketing tactics, to abandon certain industry groups, and to pay out more than $206 billion.

Fast forward to a couple of days ago, when the journal Psychological Medicine published an article showing an alleged correlation between patients smoking high-potency cannabis and damage to the white matter connections in their brains. A group of researchers from King’s College in London studied 56 individuals with first-episode psychosis and 43 individuals without any history of psychosis. The researchers took brain MRIs of the subjects and had them answer questions about their past illicit drug use, including their use of cannabis. The researchers’ primary finding was that frequent use of high-potency (meaning 16-22% THC) cannabis is “significantly associated” with altered “callosal microstructure integrity.” Basically, our body’s cannabinoid receptors are tied in with our development of white matter and gray matter in the brain, and frequent use of high-THC marijuana may cause greater than normal cell self-destruction in parts of our brains.


Correlation-based research like this is easy to attack. After the article on correlation between tobacco and lung cancer came out, the largest U.S. tobacco manufacturers came together to form the Tobacco Industry Research Committee. In 1954, the Committee published “A Frank Statement to Cigarette Smokers.” In that paper, the Committee sought to inject doubt into the nascent consensus that tobacco was bad for people. The Committee pointed out that much of the experimentation had been on mice, not people; it stated that there is no agreement between authorities that prove cigarette smoking is a cause of cancer; and it stated that statistics linking cigarette smoking with cancer could apply to any number of other possible causes. The statement was using one of the most tried and true methods of attacking early-stage scientific research — correlation does not equal causation. Showing that two events are correlated does not prove that one causes the other. Proof of causation requires a randomized controlled experiment, which would be very hard to do and probably unethical if it meant the experimental group would likely get cancer or brain damage as a result.

And so the tobacco industry was in a 40+ year war against science until it eventually crumbled. These industry vs. science battles happen all the time. The NFL has been fighting on brain damage to players. The oil and coal industries have been fighting on climate change.

So, where does that leave cannabis? Let’s assume that this research is valid and there is indeed a long-term negative effect on the brains of frequent users of high-THC marijuana. The cannabis industry is in a very different place than other industries that have faced these issues. It is more diffuse. The Master Settlement Agreement on tobacco was entered into by four large tobacco companies. We just don’t have that ownership concentration in the marijuana industry. The industry has not really coalesced yet regarding industry/lobbying groups. Some advocacy organizations are working on it, but even they would admit there’s a lot of work left before any specific group could claim to speak for the industry.

This lack of group cohesion may actually be helpful to the cannabis industry in this specific instance. The urge to put out something along the lines of the “Frank Statement” would be hard to resist, especially for those that really believe that the research showing long-term health effects of marijuana use are flawed. But that impulse to fight back against the early science is what doomed the tobacco industry. Tobacco companies spent thirty years telling the public tobacco was safe. So when they tried to change their defense to one of contributory negligence/risk assumption (“why should we pay money when our users knew all along or at least should have known all along that tobacco was dangerous?”), courts and the public saw through it. We weren’t going to let them off easy after they had perpetrated a fraud on the public for 30+ years.

So my advice to the cannabis industry is to let science run its course. Don’t look at every negative study as an attack, and don’t seek to discredit legitimate research. If subsequent research shows marijuana is safer than some of the early research suggests, great. If it shows the opposite, then communicate openly and honestly with your customers, and allow them to choose what risks to take. One of the reasons the alcohol industry hasn’t faced the same type of lawsuits as the tobacco industry is because it hasn’t played nearly as much of a role in denying science. Its arguments for risk assumption are much stronger as a result. Cannabis companies need to pay attention, so that they don’t repeat tobacco companies’ mistakes.