Humans are pleasure-driven, reward-oriented beings. We have a built-in reward system, and love to feel good and seek out experiences and substances that evoke enjoyment. However, when we rely on substances to provide us with this feel-good high, our internal reward system can become dysregulated and dysfunctional, leading to addiction.
Chronic cannabis consumption can turn into problematic use that can detrimentally affect physical and mental well-being, relationships, and daily life. And while the vast majority of cannabis consumers will not become addicted to the plant, it’s helpful to understand how cannabis misuse affects the brain, which cannabinoids can prompt addiction, and behaviors that can contribute to cannabis use disorder.
Additionally, while some research suggests that cannabis can contribute to addiction, the plant may also be a form of addiction treatment.
What is addiction?
People can get addicted to many different things, but chemical or substance addictions are the most common. Chemical addictions include drugs, alcohol, cannabis, or even caffeine (yes, it’s a real thing). There are diverse ways to talk about chemical addictions, including dependence, misuse, and abuse, but all are grouped under the broader umbrella of substance use disorders.
A chemical addiction is when an individual’s use of a substance disrupts their daily life, detrimentally affects their relationships, and hinders their ability to work. Dependence is so overpowering that they can’t stop using the substance, even though they want to quit.
Scientists generally agree that addiction is a repetitive cycle defined by three stages:
- First stage: binging and intoxication on the substance, which stimulates a flood of dopamine release that leaves the user feeling fantastic
- Second stage: withdrawal and negative effects; the absence of the substance triggers a panicked, negative reaction
- Third stage: characterized by a preoccupation with consuming more of the substance, which ultimately leads back to the first stage
An addiction to cannabis also conforms with these three stages. A formal diagnosis of cannabis addiction is referred to as cannabis use disorder.
What is cannabis use disorder?
Cannabis use disorder (CUD) can be defined as the inability to stop consuming cannabis even when it is causing physical or psychological harm. This definition not only captures addiction but also includes individuals who may be dependent on cannabis and negatively impacted by it.
Approximately 10% of 193 million cannabis users worldwide are affected by cannabis use disorder. Symptoms of cannabis use disorder include:
- Continued cannabis use despite physical problems, like frequent respiratory infections
- Continued use in spite of psychological problems, like anxiety or paranoia
- Continued cannabis use despite social or relationship problems; these problems can arise from different factors, like an impaired ability to process emotions, or a tendency to withdraw from social activities
- Giving up or reducing other activities in favor of using cannabis
- Problems at work, school, and home as a result of cannabis use
- Intense cravings for cannabis
- Difficulty controlling or reducing cannabis use
- Taking cannabis in high-risk situations, such as when driving or using tools or machines that could cause harm
- Consuming more cannabis than intended; or an inability to stick to consumption limits you’ve set for yourself
- Increasing tolerance to cannabis
- Withdrawal symptoms, like depression, or irritability, upon ceasing cannabis use
Can cannabis addiction alter the brain?
Cannabis addiction, like all substance addictions, alters how the brain processes rewards, responds to stress, manages executive system function, and self-regulates. Cannabis addiction influences executive function by hindering our ability to pay attention, concentrate, make plans or decisions, and remember important things.
Addiction also impacts how we self-regulate. Self-regulation refers to our ability to wield control over our choices, impulses, feelings, thoughts and behaviors. When we become addicted to cannabis, the desire to consume the plant may sway our choices and actions in ways that are sometimes harmful.
Cannabis addiction can also cause responses to stressful situations to become dysfunctional. For example, it’s normal to feel a spike in stress levels in response to a near-miss on the highway, or witnessing an argument. Stress causes the release of hormones like cortisol and adrenaline to prepare the body for fight or flight.
Research has shown, however, that long-term, heavy cannabis users often have a blunted response to stress—they don’t produce as much cortisol in stressful situations, and therefore don’t feel the acute effects of stress as much.
While this could be a good thing—many of us could benefit from feeling more chill in the face of everyday stressors—it could also be a disadvantage, as cortisol facilitates the release of energy that helps us to react to threats or dangers. In other words, cortisol helps us move swiftly when we need to make a speedy getaway.
Cannabis and the dopaminergic system
One of the most researched ways in which cannabis addiction alters brain function is through its effects on the brain’s dopaminergic system, which is responsible for releasing dopamine, a molecule produced in the brain that significantly influences how we experience rewards.
A toke of weed can deliver a dopamine hit that provides you with a euphoric high. However, repeated cannabis use can increase dopamine release to unnaturally high levels, which can reinforce addictive effects.
“Cannabis, when used correctly, can lead to feeling good,” explained Dr. Jordan Tishler MD, faculty at Harvard Medical School, President of the Association of Cannabinoid Specialists, and CEO/CMO at inhaleMD. “This is believed to be related to the indirect stimulation of the dopaminergic system—the system that has been implicated in addiction.”
However, it’s essential to point out that cannabis use must be chronic before addiction can take place. You can’t get addicted to weed from smoking one joint. Addiction arises when the brain’s reward system gets repeatedly stimulated, which then alters how it functions.
Cannabis and the endocannabinoid system
Our endocannabinoid system—the primary bodily system responsible for processing the effects of cannabinoids like THC and CBD—contains both naturally occurring endocannabinoids produced by the body, and receptors that pick up messages from endocannabinoids and cannabinoids in cannabis.
According to Tishler, cannabis misuse can lead to downregulation of endocannabinoid receptors, leading to fewer receptors circling in the brain—so their ability to pick up messages from the body’s normal endocannabinoid pathway is reduced. “In this way, the endocannabinoid system of the individual becomes dependent on the supply of cannabis-supplied cannabinoid,” said Tishler.
It appears that THC is the main culprit in downregulating the body’s CB1 cannabis receptors. With fewer receptors available, the brain becomes increasingly tolerant and desensitized to the rewards of THC. Therefore, increasingly large amounts of THC are needed to achieve a high.
Fortunately, however, this alteration isn’t permanent. A study of daily cannabis smokers found that the density of CB1 receptors returned to normal levels in almost all parts of the brain after four weeks of abstinence.
Are some more vulnerable to cannabis addiction?
While altered brain chemistry undeniably plays a key role in cannabis addiction, it’s important to also recognize that addiction is a multifaceted disorder caused by diverse interlocking factors. Genes, lifestyle, home and work environment, and socio-economic status can all play a role in addiction.
Beyond consumption patterns, evidence is emerging that suggests certain individuals are more likely to develop a cannabis use disorder than others.
For example, cannabis use before 16 years of age has been found to increase the risk of developing CUD. In addition, individuals with CUD are more likely to have been diagnosed with another substance use disorder, such as alcohol dependence. In a US sample of people who had been diagnosed with CUD, 83.5% of men and 82.9% of women had another substance use disorder.
Individuals with mood disorders, such as depression, are also 4x more likely to become heavy users of cannabis, increasing their risk of cannabis use disorder. However, there is some contention about whether heavy cannabis use may also contribute to depression.
Is cannabis more or less addictive than other substances?
Although there’s a saying that comparisons are odious, sometimes they’re useful in providing context. Comparing cannabis to other commonly abused substances of abuse suggests that it’s the least likely to lead to dependence.
A 2015 review that weighed up more than two decades of research found that individuals who use cannabis are less likely to develop a dependency than users of almost any other substance, including nicotine, heroin, cocaine, alcohol or stimulants.
The researchers found that the lifetime risk of developing a dependence on cannabis was about 9%. Nicotine came in at 32%, heroin 23%, cocaine 17%, alcohol 15%, and other stimulants scored 11%. This comparatively smaller likelihood of dependency may be because cannabis releases less dopamine than other addictive substances.
Can cannabis help with addiction?
While THC can contribute to addiction, another cannabinoid present in the plant, CBD, or cannabidiol, may help treat dependence. Research is still very much in the early days, but data suggest that cannabidiol may help as an intervention for diverse addictions without inciting addiction itself.
A recent randomized clinical trial with human participants found that CBD shows promise in specifically treating cannabis use disorder. CBD doses of 400mg and 800mg represented a safe and more effective treatment than a placebo in reducing cannabis use among individuals with cannabis use disorder. Of the participants, 96% had been diagnosed with severe cannabis use disorder.
While further clinical trials will be helpful in clarifying and consolidating these results, there’s a certain poetic irony that the same plant can contribute to the problem, and provide the solution.
This post was originally published on November 22, 2015.