The interplay between marijuana use and mental illness is complicated and full of unanswered questions. How marijuana affects risk of developing psychiatric disease, and conversely, how psychiatric disorders influence marijuana use, are actively being investigated in scientific studies.
Several studies have shown a link between marijuana use and an increased risk of psychiatric disorders such as schizophrenia, depression, anxiety, and other substance use disorders (Campolongo, Addict Biol, 2007). There is also mixed scientific evidence to support that marijuana use, especially during adolescence, is associated with later development of psychiatric disorders. These include increased risk of mood disorders like depression and bipolar disorder, anxiety disorders, and even psychotic disorders, like schizophrenia or cannabis-induced psychosis (Lev-Ran, Psychol Med, 2014; Bally, J Affect Disord, 2014; Gobbi, JAMA Psychiatry, 2019).
As new knowledge emerges, it is essential to stay up to date on how marijuana use interacts with mental health. Oftentimes, the nature of this relationship seems much like the “chicken and the egg” paradox, in that it is often unclear if mental health disorders preceded marijuana use, or marijuana use came before development of a mental health disorder. The bottom line, though, is that struggling with a mental health disorder is tough, as is struggling to cut back on marijuana use—let alone having to face both at once! If you or a loved one is struggling with mental health in addition to cannabis use disorder, your healthcare provider can help you navigate a path to treatment.
Anxiety and Marijuana Use
A substantial proportion of marijuana users suffer from anxiety disorders. If that’s you, chances are a big motivation for using marijuana is because it dulls your symptoms of anxiety. The bigger picture, though, is more complicated, and marijuana’s capacity to reduce some symptoms of anxiety is just one piece of the puzzle.
Studies across populations point to broad associations between personal history of marijuana use and history of anxiety. In one study, researchers pooled the data from over 112,000 people across ten countries, and found that people who use marijuana are 24% more likely to have an anxiety disorder than those who do not (Kedzior, BMC Psychiatry, 2014). Similarly, another survey of United States adults observed that people with an anxiety disorder at any point in their life were 203 times more likely to have used marijuana compared to those without any psychiatric disorders, and were also more likely to develop a cannabis use disorder after using marijuana for the first time (Lev-Ran, Am J Addict, 2013). In more recent years, rates of specific anxiety disorder diagnoses among marijuana users were 8.6% for a specific phobia, 12.2% for generalized anxiety disorder, 7.1% for social phobia, and 7.4% for panic disorder (Kerridge, Addict Behav, 2018).
What’s behind this overlap? Some experts believe that much of the increased risk demonstrated in these studies may reflect a genetic predisposition to anxiety, which becomes unmasked, or potentiated, by marijuana use or marijuana withdrawal. Similarly, the factors which lead to increased risk of anxiety—financial stress, low self-esteem, for example—may be the same ones that make people more likely to use marijuana. The relationship between marijuana use and anxiety is therefore a complicated one, with plenty of unanswered questions. For now, we can at least confirm that there’s an established connection.
Depression and Marijuana Use
Living with depression can make even the smallest of tasks seem insurmountable. Many marijuana users are no strangers to the daily challenges of living with a mood disorder. As it turns out, there is also a strong link between use of marijuana and depression.
It is estimated that individuals with a lifetime history of mood disorder—like depression or bipolar disorder—are two to three times more likely to have used cannabis and to develop cannabis use disorder compared to individuals without a mood disorder (Martins, Drug Alcohol Depend, 2011). Multiple studies have demonstrated that adults with a current mood disorder, such as depression, were at increased risk for more severe mood symptoms if they had used marijuana in the past 6 months compared to those who had not used marijuana at all (Mammen, J Clin Psychiatry, 2018).
When it comes to deciphering how marijuana and depression are related, similar thinking applies to marijuana’s relationship with anxiety. Once again, the variables that may increase your risk of using marijuana are often in common with those that predispose you to depression. Even so, there’s reason to believe that it’s not just shared risk factors that are driving this association. Only time will tell.
Psychosis and Marijuana Use
Early research suggested that marijuana use in adolescents is linked with the onset of psychosis, which is a mental state characterized by a disconnection from reality and is characteristic of psychiatric disorders like schizophrenia.
A link between marijuana and later onset of psychosis was first described in a large 1987 study. In this famous study, researchers found that participants who reported marijuana use before the age of 18 were 2.4 times more likely to develop schizophrenia, while those reporting 50 lifetime uses were 6 times more likely (Andréasson, Lancet, 1987). Other studies have found similar results, and cannabis use has consistently been linked to earlier disease onset and a more severe disease (Arseneault, BMJ, 2002; McLaren, Int J Drug Policy, 2010; Volkow, JAMA Psychiatry, 2016). In people already diagnosed with schizophrenia, continued marijuana has also been shown to worsen symptoms of hallucinations, delusions, and confused thinking (Weiss, Int J Drug Policy, 2017).
From what we currently know, individuals with genetic predisposition to schizophrenia are at particularly high risk of precipitating psychosis if they use marijuana. Furthermore, prolonged marijuana use in those with pre-existing schizophrenia can exacerbate disease symptoms.
Is Marijuana Medicine?
Many people use marijuana as a way to treat symptoms of mental health—whether you’re feeling down, on edge, or outright panicked. The hard truth, however, is that marijuana may actually sometimes exacerbate underlying issues. How do we know this? Again, the numbers tell convincing stories.
The first thing research tells us is that marijuana as a medicine for psychiatric conditions is incredibly common. In a study of 1,746 patients from a network of nine medical marijuana evaluation clinics in California, 37.8% of patients reported that they used marijuana to relieve anxiety, 16.9% to relieve panic attacks, and 55.1% to improve relaxation (Reinarman, Journal of Psychoactive Drugs, 2011). Another recent study surveyed 1,429 medical marijuana users in Washington State about the conditions they used marijuana to treat, and 58.1% reported usage of the drug for anxiety (Sexton, Cannabis and Cannabinoid Research, 2016).
So, the numbers seem to supper the anxiolytic—or anxiety reducing—effects of marijuana (Walsh, Clinical Psychology Review, 2017). Importantly, however, these studies also observed that symptoms of anxiety returned upon cessation of marijuana use, indicating that it’s not a great option for permanent treatment.
Here’s some more proof of why the short-lived, anxiety-reducing properties of marijuana be cause for concern.
THC, the psychoactive component of marijuana, appears to decrease anxiety at lower doses and increase anxiety at higher doses. Meanwhile, CBD, the less psychoactive component of marijuana, appears to decrease anxiety at all doses that have been tested (Blessing, Neurotherapeutics, 2015). There are individual differences in responses to marijuana that are affected by many factors, including the THC:CBD ratio of the marijuana strain in question. What’s more, with regular marijuana use, you inevitably develop tolerance, which is a set up for rebound anxiety upon the discontinuation of marijuana use. This cascade of tolerance and rebound fosters drug dependence (Volkow, Annual Review of Pharmacology and Toxicology, 2017). So, although using marijuana to cope with mental health issues may offer some short-term benefit, studies indicate that this effect may wane with time—before you know it, you’re left with the problems associated with marijuana use, like increased risk of other substance use disorders, without any real benefits. For what it’s worth, to date, there have been no reported randomized controlled trials to show sustained benefits of marijuana in the treatment of mental health disorders.
Bottom line: marijuana isn’t the best form of medication for a mental health disorder. If you struggle with anxiety or depression, it’s best to talk to your doctor about treatment options that have demonstrated durable benefits, including counseling, antidepressant or anti-anxiety medications. Sustainable, long-lasting options for help are out there!