Medical marijuana is at the center of therapeutic innovation for mental health. Currently, researchers are investigating marijuana and bipolar disorder.
Around 30% of people with Bipolar Disorder use marijuana on a regular basis. But, does it help or hinder their condition? Here’s what scientists know for sure, and what they don’t.
Bipolar disorder is a multicomponent illness characterized by episodes of severe mood disturbance. It’s one of the world’s leading causes of disability, affecting around 1% of the global population.
People with bipolar disorder experience ‘manic’ episodes marked by euphoria, energy and activity or ‘depressive’ episodes marked by feelings of extreme sadness and hopelessness.
Sometimes, a person in mania can experience psychotic symptoms, including:
These episodes can last for a week (or longer), and are highly disruptive to the person’s day-to-day life. The debilitating highs and lows can make it difficult to function at work and in social situations. Unfortunately, there’s no cure for bipolar disorder, but treatments can help to manage symptoms and prevent relapse.
Bipolar disorder is a chronic mental health condition, which means it requires ongoing and careful treatment throughout life. Conventional treatment can focus on stabilizing a patient's mood and include a combination of prescription medications or a range of adjuvant therapies.
Pharmacological approaches to bipolar disorder address chemical imbalances within the brain that can lead to episodes of depression, mania and hypomania. Common prescriptions medications include:
Adjuvant psychosocial therapies educate the patient about their illness (such as triggers and early warning signs) and involve developing collaborative strategies to prevent episodes from occurring. It can help with adherence to medication and improve day-to-day functioning in social, work, and family settings. Common adjuvant therapies include:
Even with these treatments, almost 40% of patients relapse into depression or mania within 1 year, and 60% within 2 years. Medical professionals, therefore, recognize a need for novel interventions. One potential therapeutic route currently under investigation is marijuana.
Marijuana is derived from the leaves, seeds, and flowers of the Cannabis sativa plant. As a naturally occurring plant, marijuana contains over 500 chemical compounds, including phytocannabinoids, terpenes, and flavonoids. Together, these chemical compounds are responsible for marijuana's wide-ranging therapeutic and recreational effects. The most biologically active compounds are phytocannabinoids, and the two most prominent of these are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).
THC is considered the main psychoactive compound in marijuana, primarily responsible for the drug’s intoxicating effects, whereas CBD is the main non-intoxicating phytocannabinoid. These phytocannabinoids exert their effects through the recently discovered endocannabinoid system. Just four decades ago, the medical world released that all humans and mammals have an endocannabinoid system. It’s made up of cannabinoid receptors and neurotransmitters–similar to phytocannabinoids, known as endocannabinoids.
So far, scientists have identified two cannabinoid receptors. CB1 receptors are expressed abundantly throughout the brain and central nervous system (CNS), and CB2 receptors are expressed predominantly in peripheral immune cells and tissues.
While the mechanisms of the endocannabinoid system are not fully understood yet, the medical world recognizes the immense potential of this new regulatory system as a new target for therapeutic drugs.
According to the National Institute of Health (NIH), there is evidence to suggest marijuana, through the endocannabinoid system, can help with the following conditions:
Although the current body of research shows great therapeutic promise, the U.S Food and Drug Administration (FDA) has only approved medications containing individual cannabinoids. A purified form of CBD (Epidiolex) is approved for the treatment of seizures, while synthetic versions of THC (Dronabinol and Nabilone) are approved for the treatment of nausea and vomiting caused by cancer chemotherapy. Due to its ability to promote appetite, dronabinol is also approved for the treatment of weight loss in people with HIV/AIDS.
In terms of mental health, some evidence suggests that marijuana and individual cannabinoids could lessen symptoms of mood, anxiety, sleep, and psychotic disorders. However, when it comes to bipolar disorder, the research findings are considered preliminary and inconclusive.
Here’s what we currently know about marijuana as a treatment for bipolar disorder.
Some research indicates that marijuana has no harmful effects on people with bipolar disorder, while other studies indicate that certain cannabinoids could alleviate symptoms.
Limited studies have examined the impact of marijuana on mood in bipolar patients. However, a pilot study published in 2016 concluded that some patients experienced a substantial, yet temporary improvement in mood symptoms after using marijuana.
Furthermore, the above study found that these symptomatic improvements were not at the expense of impaired mental performance. There was a significant difference in cognitive impairment between bipolar patients using marijuana and bipolar patients who had never used marijuana.
Contrary to what most marijuana critics believe, marijuana may actually improve memory, attention, and focus in bipolar patients.
A 2010 study involving 133 patients with bipolar found that marijuana use was associated with better neurocognition, including attentional focus, verbal fluency, and memory recall, when compared to non-use.
Evidence suggests that the endocannabinoid system may play an important role in the development of psychotic symptoms (e.g. hallucinations and delusions) experienced by patients with bipolar disorder and schizophrenia.
Two randomized controlled trials found that CBD reduced psychotic symptoms in patients with schizophrenia. However, the same results have not been observed in bipolar disorder.
In comparison to other medications used to treat bipolar disorder, CBD appears to have a more favorable safety and tolerability profile. Side effects of CBD are generally mild and infrequent, with the most commonly reported symptoms, including sleepiness, diarrhea, and increased body temperature.
Antipsychotics and mood stabilizers, on the other hand, are associated with severe side effects (e.g. sedation, seizures, liver damage etc.), which are known to contribute to nonadherence. While antidepressants are considered safe, their use should be closely supervised by a psychiatrist as, for some people, antidepressants trigger manic episodes and rapid cycling.
The World Health Organisation (WHO) has reported that there is no evidence to suggest the potential for dependence or abuse with CBD, and the potential for toxicity is very low (e.g. you cannot have a lethal dose of CBD). However, it's important to remember that marijuana is addictive and can cause adverse effects at high doses.
Although the prevalence of cannabis use among patients with bipolar disorder is relatively high, and several studies have reported that marijuana use precedes the onset of bipolar disorder, a specific cause-and-effect relationship has not yet been established.
So what does the research say about marijuana as a treatment for bipolar disorder? In particular, does smoking make bipolar worse?
A study published in 2010 found that orally administered CBD was ineffective in the treatment of mania symptoms, such as hyperactivity and irritability. Patients with bipolar disorder showed improvement in symptoms while taking CBD in conjunction with antipsychotic medication (olanzapine), but showed no additional benefits with CBD alone.
Not only have studies found the CBD is not effective in managing manic episodes, a meta-analysis published in 2015 also suggests that marijuana use may trigger manic episodes and worsen the symptoms of mania in patients with bipolar disorder. One 2009 study found that cannabis users with bipolar disorder experienced higher levels of overall illness severity and lower levels of life satisfaction compared with non-users, including a lower probability of having a relationship.
A systematic review published in 2020 reported similar findings and strongly advised against prescribing high-THC formulations to patients with psychotic disorders, particularly with youth.
A meta-analysis published in 2019, found that suicide rates were slightly higher among bipolar patients who used marijuana than those who didn't. The study involved 6,375 subjects from 11 studies, and its findings were supported by an earlier review conducted in 2015.
This study also reported that the age of onset (e.g. when symptoms of bipolar disorder first appear) was generally younger for cannabis users than non-users. This is concerning, as early-onset is commonly associated with more severe symptoms throughout a person's life.
Smoking is a particularly harmful way of administering marijuana, as marijuana smoke contains at least 50 of the same known carcinogens found in tobacco. The smoke released when marijuana is burned can also contribute to bronchitis and impaired respiratory function in regular smokers.
As with antidepressants, there is a potential for dependency with marijuana. Current statistics indicate that cannabis dependence syndrome occurs in around 1 in 10 users.
Several studies show that psychosis runs in families. For example, the lifetime risk of developing psychosis for a first-degree relative is up to seven times higher than the general population. If these individuals use marijuana, their risk becomes even higher.
Pre-existing genetic vulnerability may be related to the AKT1 gene or genes that control an enzyme called catechol-O-methyltransferase.
The Bottom Line
Overall, research regarding the safety and efficacy of marijuana in the management of bipolar disorders is scarce—and with contradictory and inconclusive results, it's impossible to say whether marijuana is a good or bad thing for bipolar disorder.
Preclinical and clinical evidence does hold promise for individuals who suffer from this debilitating condition. However, further research is needed on the short-term and long-term effects before any clinical recommendations can be made.