Depression has been called a disease of modernity. More than 17 million Americans are affected by it, and lifestyle factors can contribute to the disorder. Modern populations are often sedentary, sunlight- and sleep-deficient, socially isolated, and stressed, significantly affecting peoples’ well-being, jobs, and lives.
The relationship between cannabis and depression is complex. For some consumers, cannabis can elevate mood; for others, cannabis can worsen depressive symptoms. No clinical trials to date have focused on cannabis as a treatment for depression, so it’s currently difficult to draw decisive conclusions about whether the plant is helpful or harmful for individuals with depression.
The research that is available suggests that the connection between depression and cannabis is very nuanced. As new studies come to light, it may be that dose, cannabinoids, and use patterns can all influence whether cannabis can ease depression or exacerbate it.
What is depression?
Depression is a catch-all term for a range of mood disorders that tend to share certain defining symptoms. People living with depression often feel low, hopeless, or sad, and experience irregular sleep or eating patterns, a lack of energy, and the inability to feel excited or joyful.
The most common types of depression include:
- Bipolar disorder: Formerly known as manic depression, this disorder is defined by episodes of high energy and depressed episodes of low energy
- Seasonal affective disorder: This disorder commonly occurs in climates and regions with less sunlight during certain seasons
- Major depressive disorder: A condition characterized by persistent feelings of sadness and a loss of interest in life, which impairs daily functioning
- Persistent depressive disorder: A low mood that occurs for two years or more
- Postpartum depression: Depression that occurs after childbirth
While depression is classified as a mood disorder or mental illness, it has ramifications for physical health too. For example, adults with symptoms of depression have a 64% greater risk of developing coronary artery disease. Twenty to thirty percent of people living with heart disease also have depression.
Researchers now realize that depression is often caused by the interplay of different mechanisms. Diverse factors, both inside and outside the body, can set depression in motion, including genetic factors, environmental factors, inflammation in the brain, and others. Awareness of this diversity of factors can help construct a more complete picture of what causes the disorder and how to treat it.
Depression and the endocannabinoid system
While the factors that can contribute to depression are many, attention has recently come to the role played by one of the critical systems in the body: the endocannabinoid system, or ECS.
The ECS is a neurochemical signaling network that extends throughout the body, which helps maintain the healthy function of processes such as sleep, memory, mood, and appetite. It keeps the body in balance.
The cannabinoids in cannabis cause effects in the body via the endocannabinoid system, which is why cannabis can influence a person’s mood, appetite, and sleepiness.
While we still have much to learn about the endocannabinoid system, one thing is for sure: A well-functioning ECS is essential for maintaining mental health. Dysregulation of the ECS has already been linked to a broad range of illnesses, including psychiatric disorders.
Recent findings suggest that the ECS may play a critical role in depression. For example, one study found that women diagnosed with depression had altered levels of endocannabinoids compared to participants without depression.
In other studies, the CB1 receptors—a part of the endocannabinoid system—of rodents were removed via genetic modification, and the animals were then observed to be unable to experience joy and pleasure. Researchers also discovered that the animals had a higher likelihood of developing other symptoms associated with depression.
Is cannabis a treatment for, or cause of, depression?
A major 2020 study emphasized that while it’s clear that cannabinoids and terpenes found in cannabis could provide an antidepressant effect, no randomized controlled trials have been carried out investigating this outcome. In short, there is currently no robust clinical evidence to suggest that cannabis could be an effective treatment for depression.
While the jury may still be out on the science, many cannabis consumers have already made their own minds up. Mood elevation is one of the most commonly cited reasons for marijuana consumption. People the world over have used cannabis for millennia as a means of increasing sociability, bringing about feelings of euphoria, and altering perception.
In one recent meta-analysis, a large analysis of the results of multiple scientific studies, 34% of participants reported using cannabis to treat depression and low mood—even though there are no states in the US that include depression as a qualifying condition for cannabis use.
However, many medical cannabis patients who have depression also live with pain—and by alleviating pain, depression is often also eased. For example, depression has been reported by up to 54% of patients seeking treatment for chronic pain.
Researchers have also spent time trying to figure out whether cannabis use can cause depression—or whether depression leads to cannabis use. Recent findings suggest that both might be true, but there’s stronger evidence to suggest that depression kicks off cannabis use. One study found that individuals with depression were more than two times as likely to use cannabis on a daily basis.
Research also suggests that long-term or heavy cannabis use may also increase the likelihood of developing depression. This doesn’t mean that all long-term cannabis users or heavy users will develop depression: other factors such as sex, genes, tolerance and personal circumstances all play a contributing role as well.
How cannabis dose, cannabinoids, and terpenes can affect depression
It’s vital to point out that the relationship between cannabis and depression is extremely nuanced, a fact that many experts acknowledge is often overlooked. The frequency of use, amount used, cannabinoid concentrations, and even the terpenes present may all influence whether cannabis contributes to depressive symptoms or helps alleviate them.
Those already familiar with cannabis know that the effects of a single toke, as opposed to an entire joint, can lead to different experiences. Cannabis, like many substances, can bring about opposing outcomes at distinct doses—a phenomenon known as bidirectional effects.
In some individuals, very high doses of THC can increase depression, anxiety, and negative mood, a finding that has been echoed by other studies. On the other hand, low doses may reduce anxiety and perceptions of stress, helping to generate mild euphoria or feelings of uplift.
In many of these studies, however, precise doses were not identified, so it’s unclear how much, or how little, qualifies as a high dose or a low dose. It’s also worth noting that doses don’t affect everyone in the same way—factors such as personal tolerance, metabolism, even what you ate for lunch, can significantly influence your response to cannabis.
Until more research is carried out that specifically explores the effects of cannabis dosage on depressive symptoms, it’s hard to say conclusively exactly how dosing affects depression.
Studies also suggest that different combinations of cannabinoids may also influence whether cannabis eases or exacerbates the symptoms of depression.
There’s evidence that THC taken with CBD may be beneficial as a treatment for depression in the short term. One study found that low THC/high CBD cannabis was most effective in reducing perceived symptoms of depression. In contrast, high THC/high CBD cannabis was found to be best in reducing the perceived symptoms of stress.
Preliminary data also indicate that CBD alone may offer therapeutic benefits in the treatment of symptoms of depression. Other research found that oral CBD reduced depressive symptoms in frequent cannabis consumers. This outcome resonates with the finding that CBD can counteract THC-induced anxiety in the previous study.
Additionally, in a survey of 2,409 CBD users, many participants revealed that they used CBD for depression. The survey also found that almost 36% of participants believed that CBD treated their condition very well by itself, but it’s important to note that the data provided an overall analysis of perceived efficacy of CBD across a range of conditions, rather than for depression specifically.
Finally, it appears that terpenes present in cannabis may also contribute to the antidepressant effects of the plant. Many common cannabis terpenes, such as β-caryophyllene and myrcene, are already associated with anti-anxiety effects. Anxiety often goes hand-in-hand with depression.
There’s also evidence that several other terpenes may ease depressive symptoms. In a study where certain cannabis terpenes were compared to fluoxetine, a widely-used antidepressant, linalool and β-pinene were both found to produce an antidepressant-like effect in mice.
A unique synergy occurs when cannabinoids, terpenes, and other compounds in cannabis are combined, a phenomenon known as the entourage effect. When it comes to treating the symptoms associated with depression, harnessing the right combinations and ratios of cannabinoids and terpenes may be the key to enhancing the plant’s therapeutic benefits. Future research will tell.