Over the last 20 years, the legal and cultural status of marijuana has completely changed. When I was a high schooler in the early 2000’s, marijuana was still a counter-cultural symbol that was slightly rebellious, and definitely illegal. It was hard to get, expensive, and low quality - therefore, usage was not nearly as widespread.

Now, marijuana is relatively inexpensive, legal, available everywhere, and of much higher quality. It’s become incredibly commonly used for all sorts of purposes. Marijuana, or more specifically the active ingredient tetrahydrocannabinol (THC), activates the CB1 receptor which has all kinds of interesting and actually helpful effects. In addition to the intoxicating and pleasurable effect, activation of the CB1 receptor helps with pain, anxiety, nausea, appetite, and sleep. The CB1 receptor is expressed throughout the brain and is also implicated in memory formation, cognition, mood, and a large range of other functions.

I think there are some good things about increased marijuana access today. First of all, I think it was heinous that people used to be arrested or go to jail for marijuana-related “crimes.” In many individuals, marijuana truly does help with sleep, pain, anxiety, and other issues without creating obvious negative effects. For many, it’s just a good time, and that can be a great thing! But as an addiction medicine specialist, it’s also really important to push back a bit on the incredibly widespread use of marijuana today, and make sure people understand there are some really significant drawbacks like with any drug.

In the short term, marijuana can obviously be intoxicating. Have you ever been passed by a car that reeks of pot smoke? That’s scary! For some reason there is less stigma about driving high compared to driving drunk, but the risks are similar. Stoned driving will dramatically slow a driver’s reaction times, depth perception, and time perception.

In the longer term, marijuana can cause some very concerning neuropsychiatric side effects that are a bit unique among drugs. Have you ever felt a sense of paranoia while high? Paranoia is a common manifestation of a more generic term, psychosis — and marijuana has actually been associated with a significantly increased risk of psychotic disease, particularly when it is used frequently during adolescence. In one landmark Danish study, an estimated 8% of all schizophrenia diagnoses were suspected to be directly attributable to adolescent marijuana use. That’s a shocking figure. Once you get schizophrenia, you can never get rid of it. It’s a life-changing diagnosis. Another study found that merely weekly cannabis use during adolescence was associated with a 35% increase in the risk of psychosis, while near-daily usage was associated with a 76% increase. During adolescence, the brain is undergoing a huge amount of remodeling called “synaptic pruning”. When that synaptic pruning is occurring in the presence of marijuana, somehow the wiring can get switched around, leading to permanent psychotic illness in a not-insignificant number of people. It seems that more frequent, higher-potency cannabis use is associated with greater risks of psychosis, and that is exactly what is happening with today’s cannabis culture.

Marijuana can also significantly impact cognition. There is strong evidence that frequent marijuana use, particularly during adolescence, is associated with long term reduction in IQ and memory. Marijuana use associated with decreased long-term executive function, even after usage ends. Executive function is the brain’s high-level cognitive ability, including important skills like the ability to resist impulse, perform and execute long-term plans, assess risk, and other critical tasks. Many studies have shown associations of marijuana use and worse school outcomes including lower attendance, lower grades, and lower advanced degree attainment.

When does marijuana use cross over from a pleasant recreational or soothing activity to an addiction? Addiction has many formal criteria (see below), but the general gist is that a habit crosses over to addiction when it starts to mess up your life and you can’t stop. For example, if a college student is experiencing falling grades and increased isolation due to marijuana, and can’t effectively reduce or stop usage, that probably has crossed over to addiction. It’s important to point out, of course, that one doesn’t need to meet criteria for addiction to experience some of the negative effects of marijuana.

DSM-5 criteria for cannabis use disorder.
2-3 symptoms = mild disorder, 4-5 = moderate, 6+ = severe

Addiction is, in part, also defined by the presence of withdrawal. While many people do not experience noticeable marijuana withdrawal, symptoms can include increased irritability, anxiety, depressed mood, or worsened sleep. For a lot of people this is difficult to distinguish from the primary reason they started using marijuana in the first place, but typically it would be more of a rebound sensation, i.e. more anxiety or worse sleep than it was before the marijuana use started. But that can be difficult to determine, of course.

Cannabis use during pregnancy is a really important topic to mention. It’s very, very common and often pregnant women will use it to help with nausea and vomiting. However, I’d strongly advise using OB/GYN-recommended medications rather than self-medicating with marijuana. As I’ve already discussed above, cannabis has significant neurocognitive effects in adolescents and young adults. Think of the potential effects to a tiny growing fetus. There is a lot of data out there that cannabis use during pregnancy is linked to neurodevelopmental risks for children including autism spectrum disorders, ADHD, and other cognitive deficits. It’s not as obvious as, for example, fetal alcohol syndrome - but the effects of cannabis on the growing fetus are significant and worrisome. There is also likely a link between maternal cannabis use and preterm labor, small for gestational age infants, possibly with SIDS, and other perinatal abnormalities.

What’s tough about cannabis use, or more specifically cannabis use disorder (i.e. addiction) is that there isn’t any FDA approved medication to treat this. However, there are quite a few effective off-label medications that have been studied. In my opinion, the best study comes from Levin and colleagues in 2011. They used a drug called dronabinol vs placebo to treat 156 patients with cannabis addiction. Dronabinol is a synthetic form of cannabis that is primarily used in cancer patients and others with significant malnutrition. It can have similar side effects to actual cannabis, but is much less potent and easier to control. Patients who received this medication over a period of several months in a controlled taper experienced dramatically improved withdrawal symptoms. In my previous life as an internal medicine doctor I used dronabinol occasionally to treat cancer patients with anorexia, and sedation is one common side effect I noticed, but it was usually pretty tolerable. I’ve used it in patients with cannabis use disorder and found it to be really successful.

Reproduced from Levin et al, 2022. WDS = withdrawal severity

There are a few other medications that have been studied. N-acetylcysteine (NAC) is a supplement that seems to have some neuromodulating effects and has been shown to be effective in teens/adolescents in reducing marijuana use and craving, though the studies have been pretty small to my knowledge. NAC has not been shown to be effective in adults, but we’re talking about small studies that are not terribly conclusive. I think NAC has minimal downsides and is a very reasonable therapy to try.

Naltrexone is a medication we use in the addiction field primarily to treat alcohol use disorder (alcoholism), but due to its modulating effects on the endorphin system, it has interesting effects on a large number of addictive behaviors, ranging from gambling to smoking to overeating. It turns out to also have some potential effect on cannabis use. In several studies it was shown to reduce cannabis use when compared to placebo. Naltrexone is another medication with minimal downsides and is worth trying out. I should note that all three of the above medications work through different mechanisms and can be combined as necessary.

Ultimately, the treatment of cannabis use disorder is going to hinge a lot on individual patients’ needs. Many need a close exploration of why they were using cannabis in the first place, whether that might be for anxiety, pain, sleep, etc., and then we treat the underlying condition. Patients are often isolated to some degree, and rejoining some form of positive community can have powerful anti-addiction effects. A lot of times an external motivation is helpful - parents or school, most commonly.

The bottom line is this. For many people, cannabis is a helpful substance that facilitates relaxation, anxiety relief, pain relief, and socialization. Let’s be honest. It can be a good time. But for some, cannabis use can cross over into addiction. Though we don’t have FDA-approved medications for this, we can (1) treat the underlying issues, and (2) treat the cannabis use itself with several promising medications.

When does cannabis use cross over to cannabis addiction?

So what does an addiction doctor do?