Q: How addictive is cannabis?
A: As an emergency physician in inner cities such as Detroit and Baltimore for the last 25 years I am, unfortunately, very familiar with caring for patients with addiction. Over the years, I have seen the nomenclature change from “drug abuse” to “substance abuse” to, now, “substance use disorder.” I became interested and started my cannabis medical practice because of the opioid crisis and my dismay at our profession’s unwitting participation in it, while trying to help our patients and end their pain and suffering. I feel the agencies like the FDA that are supposed to protect our patients have instead shielded the pharmaceutical companies like Purdue, who, like the tobacco companies, also hid the addictive nature of their products.
Addiction specialists describe a general model of addiction as a chronic relapsing disorder that is characterized by a compulsive desire and use of a substance, with an inability to control it, despite all the negative consequences. Researchers talk about three circular phases, described by a cycle of behaviors modified by the central nervous system circuitry. A brief general overview describes the reward centers in the brain called the nucleus accumbens part of the basal ganglia that drives the intoxication and binge use, while the withdrawal and negative effects are driven by the changes in the part of the brain called the amygdala, leading to the preoccupation and anticipation of the substance driven by the prefrontal cortex starting the cycle again.
All drugs of abuse increase dopamine release, the neurotransmitter associated with our pleasure and reward systems that drives and reinforces use. While the two main cannabinoids in cannabis, THC and CBD, can both affect dopamine responses, it is believed that THC, which is the psychoactive component, is responsible for cannabis’ addictive potential and abuse liability.
Additionally, over the last two decades there has been a marked increase in the potency of cannabis with ever-increasing levels of THC. The DEA reports rise from 1-2% THC found in confiscated marijuana from years ago to upwards of 20% THC today. With respect to THC, animal models have shown that THC does have characteristics of an abuse liability with drug dependence, associated increased dopaminergic activity, withdrawal syndrome and it does induce animals to self-administer the drug.
In humans, it is believed that chronic cannabis use, especially in adolescents, leads to addiction or addictive behaviors. Approximately 9% of all users in the US, one-fifth of whom began using as adolescents, have cannabis use disorder. It is defined by the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DMS-5), as a problematic cannabis use with significant impairment occurring within a 12-month period.
CBD is the other major cannabinoid in cannabis; however, it is non-intoxicating. In part, this may be related to the fact that it does not have affinity for the CB1 receptors, and it may actually be a negative allosteric modulator for the CB1 receptor, meaning it weakens the binding of THC and thus makes THC’s psychoactive effects much less, depending on the CBD concentration and ratio compared to THC.
CBD has some anxiolytic (anti-anxiety) properties which are proposed to be due to its 5HT 1A (serotonin) agonist activity but it is not considered hedonic (pleasure-inducing) on its own. And that is why in human or animal studies, CBD it is not believed proposed to have abuse liability. Additionally, while not fully understood, it is proposed that CBD’s influence on both opioid and dopamine receptors, which play a role in our brain’s motivation and reward system, may lessen drug cravings and withdrawal symptoms for addicts to other substances. Human studies have shown it may help with addiction and withdrawal symptoms even in cannabis use disorder. And animal studies have shown that topical CBD can attenuate the self-administration of cocaine and alcohol in relapsed-stressed rats.
So, in regards to which component of cannabis has an abuse potential/liability, in my opinion, it is THC, not CBD. But having practiced for so many years treating addicts of all kinds, my opinion is that the majority of those who have dangerous addictions are not those with cannabis use disorder. In fact, this disorder was only recently added to the DSM-5 which, combined from 4th edition DSM-4 the two separate entities of substance abuse (with its negative social context) and substance dependence (with its physiological and psychological context).
Additionally, as a physician it was always difficult to even assess much of the available research because as a Schedule I drug, the federal government and NIDA are biased and have historically only funded research for cannabis that showed harm, I believe one must take all this published literature with the proverbial grain of salt.
When comparing withdrawal symptoms of cannabis use disorder, most agree that opioid and cocaine withdrawal symptoms are much worse than cannabis and are a bigger issue with regards to relapse, while alcohol and benzodiazepine withdrawal can be fatal if not properly treated. Cannabis use disorder is not associated with deaths from overdoses like we have seen every day with the opioid crisis. Yes, of course, we need to keep cannabis out of the hands of minors and adolescents, and we need to make sure that, just like with alcohol, no one is driving while under the influence. And while using cannabinoids for addiction treatment is intriguing, we do need more research, as there is some conflicting evidence on whether it does reduce opioid-related deaths in states that have legalized it.
In my medical cannabis practice today, while long-term use may cause some dependence, I am not seeing lives ruined as they have been with opioids, cocaine, methamphetamines, or alcohol, nor have I seen the physical carnage and disease that tobacco addiction has caused. And my colleagues in states where recreational cannabis is legal have observed the same.
Dr. Leigh Vinocur is a board-certified emergency physician who also has a cannabis consulting practice for patients and industry. She is a member of the Society of Cannabis Clinicians and a graduate of the inaugural class, with the first Master of Science in the country in Medical Cannabis Science and Therapeutics from the University of Maryland School of Pharmacy.
Originally published on greenstate.com, January 4, 2022.