Is Cannabis Safe? A New NOVA Film Explores The Complex Risks And Benefits

Marijuana has been legal in Massachusetts for adult use for several years now, but there's still not much known about the widely-used drug. A new NOVA film called The Cannabis Question investigates the latest scientific evidence of its potential benefits and risks, and how criminalization has disproportionately harmed communities of color. Sarah Holt, the film’s writer, director and producer, joined Sean Corcoran on Morning Edition to discuss. This interview has been edited for clarity and length.

Sean Corcoran: Sarah, this film explores our relationship with cannabis and the effects on the body and the brain. Are you focused on THC, the chemical found in marijuana that gives people that feeling of being high, or CBD, which is being marketed as somewhat of a cure-all in creams, pills, teas, even products you would give your pet?

Sarah Holt: The film looks at both — we look at THC, but then we also look at how CBD is being used to treat conditions like epilepsy. And you know, those are not the only two cannabinoids in the plant. It's a very complex plant with over 500 chemicals.

Corcoran: What have we learned recently about the effects of cannabis?

Holt: I think one of the most amazing to learn during the show was that we make our own cannabis-like molecules and they bind to receptors in our brain and body, and cannabis mimics those molecules. And these molecules in our body form one of the most important regulatory systems, most people have never heard of, called the endocannabinoid system, and it regulates things like appetite, cognition, memory, mood. So when you use cannabis, you are engaging this system.

Corcoran: Could you be hurting that system in some way?

Holt: I think it really depends. It depends on if you're using it as a teenager or as an adult; if you use it every day or you use it infrequently or occasionally; if you're using a high dose or low dose. Cannabis is not one thing. The plant is incredibly complex, and there are so many different factors that can determine whether it could be beneficial or maybe harmful. It's complicated.

Corcoran: Why has there been such limited research on cannabis?

Holt: Amazingly, cannabis is deemed as dangerous as heroin. It's a schedule one drug, and it's very hard for scientists to do research. So, when you walk into a dispensary, what you really see on the shelves is a voter-approved cannabis. This is not FDA-approved cannabis. The markets are moving ahead of the science.

Corcoran: Let's talk some more about the benefits and the risks that you found. What really stood out for you in terms of benefits and risks?

Holt: One thing that I was aware of was people with PTSD — early evidence shows that cannabis is incredibly helpful for the night terrors, for anxiety. We know that there's evidence that CBD is useful in alleviating certain types of epilepsy. Cannabis THC, especially, is useful for people going through chemotherapy, and it also helps reduce the nausea and increase appetite, and it also seems to be very beneficial for sleep.

One caveat, though, is that some people — about nine percent — will develop a cannabis use disorder or an addiction. So, it's not a benign drug, and it does seem to have a serious impact on the developing brain. If the fetus is exposed to cannabis, there's a greater likelihood that they are at an increased risk for depression and other mental health disorders later in life.

It can impair cognitive abilities in teenagers. They perform less well on cognitive tests. If they stopped smoking cannabis, those abilities can bounce back. It doesn't seem to be great for the developing brain, but when it comes to adults, cannabis used occasionally is probably safer than most drugs that are out there: alcohol, tobacco, opiates.

Corcoran: And in the recreational market that you referenced, if you go in, there are all sorts of different strains and different types. Do those make a difference in the in the benefits or the risks that you're taking?

Holt: Well, certainly potency. There is some very high-potency THC out there, and if you take too much, you can end up in the E.R. with temporary psychosis or extreme anxiety. There are so many different products — unfortunately, scientists need to study these products.

Corcoran: Do we know how rare or how often those types of things happen, the psychosis that you referenced?

Holt: They're rare events, but they can happen. People need to know you can take too much THC. You can't overdose really on cannabis, but you can take too much.

Corcoran: The film also takes time to look at the criminal implications of marijuana. Despite the fact that government data shows usage is equal across races, more people of color are arrested for cannabis-related offenses. Can you talk about that and what you discovered there?

Holt: It's amazing to me that during the pandemic, cannabis was considered an essential service and yet some 40,000 Americans are behind bars for cannabis offenses, primarily just for possession. And people of color are almost four times more likely to be arrested than white users. It’s really tragic.

We follow a veteran in the film who had a third of an ounce of medical cannabis legal in Arizona; he stops to get gas in Alabama and ends up with a five year prison sentence. And [he] enters prison at the height of COVID, so it could become a death sentence. And here he is, a veteran who served for the U.S., Purple Heart, dismantling roadside bombs, severe PTSD and used cannabis to cope. And he ends up in prison in Alabama.

Learn more at an Oct. 7 Virtual event: NOVA "The Cannabis Question" Discussion & Live Q&A
Stream The Cannabis Question