What Does the Research Say on Cannabis and Mental Illness?

cannabis plant leaves

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Cannabis.  It’s a plant that’s well known for getting people high, but it’s also become increasingly accepted for medicinal purposes, particularly for pain and nausea.  But what do we know about the interaction between cannabis and mental illness?

There’s been a clearly established link between cannabis use and triggering the onset of psychotic illness in people who are susceptible.  When it comes to mood and anxiety disorders, there isn’t as much research.

Cannabis is now legal in Canada and a number of American states, and I suspect that one of the benefits of this is that there will likely be increased funding available for cannabis research.

The Canadian Institutes of Health Research, a government agency, currently has a competition open for grants to conduct cannabis research.  The amount earmarked for mental health research is $4.5 million.  Doing a quick search I wasn’t able to find an estimate of research dollars in the U.S.

Hopefully in a few more years we’ll have a much better understanding of the science of cannabis.  But here’s a brief look at what science can tell us now.

What’s in cannabis?

While Cannabis sativa plants contain more than 100 different types of cannabinoid elements, two in particular appear to be key in mediating the health effects of cannabis.

Delta-9-tetrahydrocannabinol (THC) is responsible for the psychoactive effect, or “high”, that cannabis produces. It also has analgesic and anti-nauseant effects.

Cannabidiol (CBD) is non-psychotomimetic, meaning it does not cause a “high”; in fact, it may even counteract that effect of THC. It’s being researched for potential use in a number of different health conditions, including epilepsy.

Both THC and CBD act on cannabinoid receptors in the brain, much like the body’s own natural endocannabinoids do.  This is along the same lines of how opioids act on the body’s endogenous opioid receptors.  As with opioids, the fact that these molecules act on endogenous receptors is not inherently a good or bad thing.

Endocannabinoid receptors

The endocannabinoid system involves two key receptors, CB1 and CB2, and influences a variety of cognitive processes including learning, memory, mood, sleep, and motivation.

The anti-obesity drug rimonabant acts as an antagonist at CB1 endocannabinoid receptors, and it can produce symptoms of depression and anxiety in individuals without mental illness. This suggests that decreased natural activity at endocannabinoid receptors can negatively impact serotonin signalling in the brain. One study found lower than normal concentrations of CB1 receptors in autopsies of the brains of depressed people.

THC is a CB1 and CB2 agonist. CBD boosts activity of one of the body’s natural endocannabinoids, and antagonizes the effects of THC.

Cannabis use and mental health

A statement by the National Academies of Science, Engineering, & Medicine found evidence of a number of mental health  effects associated with cannabis:

  • Moderate evidence of increased symptoms of mania and hypomania in people with bipolar disorder with regular cannabis use
  • Moderate evidence for a small increase in the risk of developing depression
  • Moderate evidence of increased suicidal ideation, attempts, and completion
  • Moderate evidence for increased social anxiety disorder among regular users
  • There is no evidence indicating for or against an effect of cannabis on changes in symptoms or course of illness in people with depression
  • There is moderate evidence that depression is a major risk factor for developing cannabis abuse

According to Lev-Ran et al., multiple large cross-sectional studies have demonstrated high rates of co-occurring cannabis use and depression, although that level of evidence is insufficient to make inferences around causation.

In a meta-analysis of longitudinal studies, Lev-Ran et al. concluded cannabis use was found to moderately increase the risk of developing depression, with a somewhat larger increase in risk associated with heavy cannabis use. Similar results were found in both adult and adolescent populations. The mechanism for this was unclear, and the authors suggested that it could be related to direct effects on cannabinoid receptors, or it could be mediated indirectly by psychosocial consequences of cannabis use.

A study by Agrawal et al. found that heavy cannabis use was associated with an increased incidence of depression and suicidal ideation.

A study by Blanco et al. did not find a significant association with cannabis use and the development of depression.  A study by Schoeler et al. concluded that onset of cannabis use before age 18 was associated with an increased risk of developing MDD, but late-onset use (after age 27) was not.

Feingold et al. found that people with depression were more likely to start using cannabis, and the authors suggested this might e a form of self-medication.

What does this mean?

One of the benefits often ascribed to cannabis is that it’s a natural alternative to pharmaceuticals. However, the fact that a substance is plant-based rather than synthetic does not necessarily mean that the substance is either a) therapeutically effective, b) safe, or c) free of unwanted effects (i.e. side effects).  If cannabis has therapeutic benefits that’s great, but for me the “natural” argument in and of itself doesn’t hold water.  And with these findings, the biggest take-away message that I’m getting is that more research is needed.

Hopefully with government research funding agencies offering more grant money for research into the effects of cannabis, we’ll have a clearer picture of how components the various components of cannabis affect mental health and mental illness.  It would be particularly interesting to see what potential role CBD might play.  Until the science is there to back it up, though, it’s probably not something that I’m going to be putting into my body.

 

References

 

Have you checked out my new book Making Sense of Psychiatric Diagnosis?  It’s available on Amazon and other major ebook retailers.  It’s also available on the Mental Health @ Home Store, along with my first book, Psych Meds Made Simple.

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47 thoughts on “What Does the Research Say on Cannabis and Mental Illness?

  1. sophienaylor1 says:

    I personally think there’s a lot of research to back up cannabis being beneficial towards people’ mental health, however it’s not for me. I used to smoke it a lot, but it just makes me anxious. However, there’s so many people I know who smoke it to calm their anxiety and depression down. I think it depends on the person. I do think people should stop shutting it down just because it’s an illegal drug. Alcohol was illegal once too, now people drink it all the time because it’s normalised. Cannabis, from my experience, is way less dangerous than alcohol. There’s a lot of people who have spoken up about cannabis helping them enormously with physical and mental health issues, so I don’t think they should be shut down and ignored just because the government has decided a plant is illegal. I’m going off on a bit of a tangent here so I’ll stop now! Haha. Really interesting post though – I haven’t seen much written about this topic on WordPress.

  2. Alexandra A says:

    Synthetic drugs come from natural derivatives, so you’re right that that argument is somewhat flat. Marijuana has not been researched because of people’s negative views or stigmas toward it. Marijuana is a plant with leaves and a flower, so I’m into it. The “high” is different for anyone and I’m not a doctor, so I’m not prescribing. We need to now MORE, and we need to know more like, yesterday.

  3. Marty says:

    In America if you have chronic pain

    I was in a triple rollover with damage to my cervical spine

    After fusions and nerve killings my pain was unbearable

    Chronic pain is a whole different animal

    So through workers compensation I had a PhD. Pain psychologist, neurosurgeon couple neurologist and two pain doctors

    I was in a chronic pain group

    15 of us met weekly

    The norm was maybe 19 yo 15 pills a day

    The strong opioids and anti anxiety pills dominated

    We were all over medicated and our pain pills lost power and side effects were numerous.

    I walked out of that group thru my pills away and substituted medical weed

    Since legalization the quality and cleaner products have emerged

    For us chronic pain sufferers weed has more than one benefit

    Nausea, vomiting and lack of appetite plague us

    Weed solves this problem and kills much of the pain

    I would be dead by now on the opioids and prescription drugs

    The side effects grew and those pills took my willpower

    It is a personal choice

  4. BeckiesMentalMess.wordpress.com says:

    Very interesting. I’m looking into CBD oil for my chronic pain. I certainly don’t want anything else affecting my mental health.
    I used to smoke a lot, and I mean a lot of weed when I was in my late teens through late 20’s. It wasn’t until I experienced my first panic attack that ended me up in the hospital that I quit smoking.
    Thanks for sharing this… Again, I know to check with my general practicioner before taking cbd oil. Lord knows the psychiartrist wouldn’t say yes or no. She’s the one that prescribes my meds, and she couldn’t give me a yes or no answer? Wrong.

  5. The Inquisitive Mind says:

    This is a solid scientific assessment of both the potential harms and benefits of cannabis use! It is very important that we understand the true nature of the drug before we decide to put it into our bodies. I really agree with your overall conclusion in the drug not being a healthier simply because it’s natural, and that research needs to continue on the subject. I think objective research and education will be much more powerful in deterring people from the drug. This is why this is a particularly great post; because it uses scientific research to support your claims. Hopefully we can continue to gain scientific evidence, but this is also a controversial subject at the moment. Great job summarizing the current state of cannabis research!

  6. Marty says:

    If you have chronic pain cannabis is not a theoretical discussion

    You are faced with a few choices

    There are the internal devises
    A phentnyl lump or electrical stimulator

    Nerve killing surgeries

    Opioids

    Cannabis

    Or throw the pills away and summon your own endorphins through aerobic exercise

    I went from 8 pills a day, phentinyl patch to none

    Cannabis, meditation and aerobic exercise

    You have to make a choice or suffer

  7. Mira Afiouni says:

    This field is expending in a tremendous way that nobody ever expected it to! I think we have to wait and see, what more research and studies will provide ! thanks for sharing !

  8. Meg says:

    Wow! You’re a natural scientist! I didn’t know any of this stuff, but I’m glad you wrote about it! I’ve never smoked pot, but I used to be curious about it and want to try it. My evil sister, in a rare moment of possibly not being evil, said, “You shouldn’t do it. Pot can increase your paranoia.” So I never have. I had hoped, though, that any research or findings thus far would’ve been more positive and hopeful for mental health applications! Oh well! I’m pretty comfortable with prescriptions, anyway.

    But definitely keep us informed of future studies and their implications! I almost think the pharmaceutical companies should consider utilizing pot as an ingredient for different sorts of medicines, but I have no clue how that works. Very informative!!

    • ashleyleia says:

      Yeah, marijuana’s definitely not a good choice for anyone with a psychotic illness. There already are a couple of synthetic versions of THC available by prescription, but I think a limiting factor when it comes to marijuana is drug companies aren’t going to get too involved in anything they can’t patent.

    • Jonathan says:

      Pot *can* increase your paranoia. But it may also decrease it. I’ve had both in my personal use of it (as someone with bipolar disorder). One of the big factors is the type of cannabis. I am not sure but I think indica strains are better for reducing paranoia. Sadly, where i live it’s illegal, and the criminals you have to buy off have no idea what kind of plant it is.

  9. Michelle says:

    I have looked into CBD for a while. I haven’t tried it because there is no scientific evidence it will work. I was surprised when I heard pharmacies would be selling it

    • ashleyleia says:

      It’s unfortunate that the process for getting herbal supplements andthat kind of thing into stores has a very low bar in terms of demonstrating effectiveness for any kind of health condition.

  10. Casey Elizabeth Dennis says:

    I’ve found great benefits for my mental health using marijuana, reduces my mood swings & helps when I’m depressed. But I still need other meds with it. I think there needs to be more research. I know there’s conflicting studies on whether it damages adolescent brains or not. They use to tell us it kills brain cells, come to find out it doesn’t. I think it depends on each person. I’ve seen some people who get extra paranoid while it helps my anxiety. I’ve seen others use because they’re depressed and others who became depressed because they used. I do know it’s great for pain, though.

    • ashleyleia says:

      Yeah the effects on mental health seem to vary quite a bit from one individual to the next, but the positive effect for pain seems a lot more consistent.

    • ashleyleia says:

      I think it’s a good idea for anyone with a mental illness to be careful about what they’re putting in their body. You certainly don’t want to try something that might potentially worsen your illness!

  11. Mathew | Blog of the Wolf Boy says:

    Some of those studies make me question whether the weed caused people to have suicidal ideation and depression or whether they were using cannabis as a way to deal with the emotional problems that were already present.

    For me, cannabis has been both helpful and harmful depending on how much I use. I agree that when it’s abused (used 2 or 3+ times per day) it’s caused me to become paranoid, anxious and lazy. However, if I’m just hitting the sweet spot of approximately 1 time at night before bed, it’s the perfect amount to just wind me down, relieve my stress and lull me to sleep. As long as I keep it in that sweet spot, I’m a firm believer that cannabis has helped to improve my life in massive ways! It’s also helped me stay away from alcohol which I was abusing before Cannabis, off and on. Certainly a healthier alternative.

    More research would be nice. Great post.

  12. Jonathan says:

    Like a number of others here, I live with a serious “mental illness”, namely bipolar disorder, and find cannabis helpful.

    I find edible cannabis (of the sort that gets you high) hugely beneficial in managing myself. I have found that cannabis actually helps when I’m depressed, it lifts me up, brings a little joy and light into my life when I’m having dark times. Anecdotally it appears plenty of those with a mental health diagnosis use cannabis to ease their life. A friend living with anxiety eats cannabis edibles to help with her off days. I know people living with a schizophrenia diagnosis who find cannabis calms them. This is what the anti brigade won’t tell you – cannabis actually helps many people with “mental illness”. Eating cannabis has enabled me to train my mind to think positively, through ruminations while high. For this, I am grateful, and happier than at any time before in my life.

    There is not much research on using cannabis to help with mental illness, mainly because until the last few decades researchers COULD NOT legally investigate. I am hopeful that in coming decades there will be a lot more research. One 2018 study showed that of

    Finally, I recommend everyone who lives with a so-called “disorder” to find out about Mad Pride. We are not second class citizens.

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