Mental Health & Medical Cannabis: What We Know

Alternaleaf Team
Written by
Alternaleaf Team
Oct 26, 2023
Last updated:
Jan 19, 2024

Cannabis and mental health have a complex and sometimes confusing relationship. People commonly associate cannabis use with poor mental health, but emerging research suggests medical cannabis may have some use in the management of mental health disorders such as anxiety, PTSD and depression.

Some researchers also now believe that the negative effects cannabis can have on mental health are far more prominent among those who use cannabis very frequently and/or use products that are excessively high in tetrahydrocannabinol (THC).

That’s not to say that cannabis, even when used under medical guidance, isn’t risk free. People with mental health concerns should be cautious when using medical cannabis and some people should avoid it entirely, particularly if you have a personal or family history of psychosis.

To better understand the relationship between mental health and cannabis use, it’s useful to examine the psychoactive properties of THC and how it can affect people differently. Then, we’ll have a closer look at how medical cannabis might be able to help those with anxiety and other mental health disorders.

What Causes the Psychoactive Effect In Medical Cannabis?

Most medical cannabis products (with the exception of isolate CBD oil) contain THC, which is the compound in cannabis that causes a ‘high.’ For some people, THC can be relaxing. For others – especially those prone to anxiety – it can increase anxiety and even lead to paranoia or panic, especially when taken in high doses.

THC is the primary cannabinoid in the cannabis plant. Cannabinoids act on your body’s endocannabinoid system, which is involved in regulating several bodily functions, including your mood. THC primarily binds to the CB1 receptors, found mostly in the central nervous system.

CBD on the other hand, acts as a modulator to THC, meaning it can lessen the psychoactive effects of THC and has minimal psychoactive effects of its own. Researchers are studying CBD for its many potential health benefits, including as a treatment for several mental health conditions. CBD is the second most prominent cannabinoid found in the cannabis plant cannabis, and mostly affects the CB2 receptors, found in the peripheral nervous system and immune cells.

Can CBD Oil Benefit My Mental Health?

In 2019, researchers used a randomised controlled trial to assess CBD’s potential for helping manage social anxiety disorder. They found that a single dose of CBD significantly reduced anxiety levels in participants compared to placebo, but acknowledged that long-term studies are needed to further explore this.

Another 2019 study on CBD focused on how it might reduce anxiety and improve sleep over several months. The researchers found that 79.2% of the 72 participants experienced reduced anxiety in the first month, while 66.7% had improved sleep, although the improved sleep was not consistent over time.

CBD may also have some effect on serotonin levels in the brain. Serotonin is a neurotransmitter that is involved in emotional regulation, mood and stress, and is a target of several traditional antidepressants. Researchers have primarily explored CBD’s potential antidepressant effect using animal studies, so more human research is needed before we can say with any confidence that CBD might help manage depression.

Can THC Benefit My Mental Health?

An article in the Australian Journal of General Practice reviewed some older studies and concluded that THC may reduce anxiety in those experiencing chronic pain or cancer pain. The researchers stated that THC’s pain-relieving effects may have contributed to the patients’ reduced anxiety.

More recent evidence also indicates that THC may have some use in reducing nightmares associated with post-traumatic stress disorder (PTSD) through its ability to modify REM sleep (the sleep stage when dreams occur). The review notes, however, that the evidence for treating PTSD with medical cannabis remains ‘largely hypothetical’, and that randomised controlled trials are needed to further explore the potential benefits. Another older study supports these findings, however, with participants experiencing reduced hyperarousal symptoms and reduced nightmares associated with PTSD.

If you are struggling with your mental health, it’s important to talk to a doctor before starting or changing treatments.

What Risks Does Using Medical Cannabis Pose To My Mental Health?

When used under the guidance of a medical professional, medical cannabis is unlikely to negatively impact your mental health. However, using illicit cannabis, high-THC strains, using frequently and/or heavily may pose risks for your mental wellbeing. Chronic cannabis use may also have some effect on cognition and memory.

Doctors in Australia generally do not prescribe medical cannabis if you have a personal or family history of psychosis. There is evidence to suggest that cannabis can bring forward a psychotic episode in vulnerable people, or potentially cause a psychotic disorder such as schizophrenia to develop.

A 2017 study found that the rate of developing schizophrenia or bi-polar disorder among a population of people who had experienced cannabis-induced psychosis was 47.4%. The study found that the group most at risk were males between 16 and 25 years old. Another study found that people who frequently used cannabis, especially cannabis high in THC, were at a higher risk of developing a psychotic disorder.

Adolescents also shouldn’t use cannabis, as there is some evidence that suggests it can negatively impact a developing brain. One review looked at adolescent cannabis consumption and found an increased risk of developing depression among those who consumed cannabis as adolescents. Medical cannabis clinics don’t prescribe to people under the age of 18 for this reason.

Heavy cannabis use may also increase the risk of depression. One review noted that high-THC cannabis may be associated with a higher risk of depression. They also found that the opposite may be true – that depression can lead to problematic cannabis use. Because of this, the relationship between cannabis use and depression is often unclear.

The review concluded that low doses of cannabis can generally have positive effects for your mental health, whereas high doses can pose risks and potentially cause or worsen mental health conditions such as depression.

Is Medical Cannabis Addictive?

Cannabis can be addictive in some users, but when used with a doctor’s guidance you’re very unlikely to experience addiction. Cannabis withdrawal also tends to be non-serious, but there are a few things you should know about cannabis addiction and withdrawal.

If you regularly use more than the recommended dose of medical cannabis, you may be at risk of developing a dependance on the medication. This can sometimes be seen with recreational users of cannabis and several other illicit drugs, and involves feeling withdrawal symptoms when not taking the drug. Cannabis withdrawal symptoms can include irritability, anxiety, difficulty sleeping, changes in appetite or weight, depression, restlessness or difficulty concentrating.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM), cannabis withdrawals will likely begin 24 to 72 hours after you stop using cannabis, peak within the first week and last around 1 to 2 weeks. Sleep issues from cannabis withdrawal may linger for up to a month.

Note that THC is the potentially addictive compound in medical cannabis – isolate CBD products don’t pose any risk of addiction. Researchers believe that the potential addictive properties of THC are due to its interaction with the CB1 receptor, which CBD doesn’t interact with.

Medical cannabis may also have some use in stopping or reducing other substance use. A recent study involving a population of 2,183 medical cannabis users looked at their use of other medications. 60% of the participants used opioid pain medications (which can be addictive) prior to medical cannabis, and 79% of this group reported stopping or reducing their opioid use after beginning treatment with medical cannabis.

These findings suggest that for some people medical cannabis might be a safer alternative to more addictive pain medications, but more high-quality research is needed to confirm this. It’s also important to discuss with your doctor before making any alterations to your medication regimen.

Should I Use Medical Cannabis For My Mental Health?

Using medical cannabis according to your doctor’s advice may help if you experience anxiety, depression or PTSD. THC’s pain-relieving properties may also benefit the mental health of people experiencing chronic or cancer-related pain. But like other medications, cannabis can pose risks for your mental health when overused or purchased illicitly.

THC is psychoactive, meaning it can affect people in different ways, so it’s essential to be informed about the risks and benefits of medical cannabis. If you’re concerned about your mental health, you can speak with a doctor about CBD isolate products, or ask if THC may improve your specific condition. Medical cannabis has many different forms and applications, so ask your doctor about a treatment type that might be right for you.

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