Shared Genetics for Cannabis Use and Psychiatric Disorders

Summary: Researchers discovered shared genetic underpinnings for cannabis use and psychiatric disorders like schizophrenia and bipolar disorder. Employing advanced statistical modeling, the study revealed a complex interplay of genetic variants increasing or decreasing risk factors for these conditions.

These findings may contribute to personalized preventive measures and interventional strategies. Furthermore, improved understanding of this genetic overlap could aid in more specialized treatment plans.

Key facts:

  1. The study identifies shared genetic factors increasing the susceptibility to both cannabis use and certain psychiatric disorders.
  2. Some genetic variants can have opposing effects – increasing risk of cannabis use while decreasing the risk of schizophrenia or bipolar disorder.
  3. These findings can potentially revolutionize preventative measures, intervention strategies and the development of more targeted treatments.

Source: University of Oslo

A new study from the University of Oslo published in the Lancet Psychiatry, reported a shared genetic basis for cannabis use and psychiatric disorders, including schizophrenia and bipolar disorder.

These findings may indicate that a subset of the population is at high risk for both cannabis use and psychiatric disorders, based on their genetic propensity.

There has been much debate over the relationship between cannabis use and psychiatric disorders. Cannabis is a psychoactive drug which sometimes produces psychotic-like symptoms.

Additionally, the rate of cannabis use is high among patients with disorders linked to psychosis, such as schizophrenia and bipolar disorder.

This shows two stills of a person's head.
Genetic factors play an important role in determining an individual’s susceptibility to developing psychiatric disorders or their likelihood of using cannabis. Credit: Neuroscience News

Genetic factors play an important role in determining an individual’s susceptibility to developing psychiatric disorders or their likelihood of using cannabis. Some of the genetic variants associated with cannabis use are also linked to psychiatric disorders.

This recent study, led by Drs. Weiqiu Cheng and Nadine Parker, provides evidence that shared genetic factors underlie this relationship.

“This study shows that there is a shared genetic basis underlying our susceptibility to both cannabis use and certain psychiatric disorders. These findings may indicate that a subset of the population is at high risk for both cannabis use and psychiatric disorders, based on their genetic propensity”, lead author Weiqiu Cheng says.

Using advanced statistical modeling, the study shows that the majority of shared variants increase the risk of both cannabis use and developing either schizophrenia or bipolar disorder.

Still, there are some genetic variants with opposing effects, that increase the risk of cannabis use while decrease the risk of the two psychiatric disorders, suggesting a complex relationship.

“These findings are important as they show that the complex links between cannabis use and these disorders may not only be caused by cannabis use itself, but could also be driven by shared genetic susceptibility”, researcher Nadine Parker says.

Cannabis is used medicinally for relief of pain and as an antidepressant in some regions of the world. Also, one component of cannabis is being considered as a potential treatment for psychosis.

“Shared genetic variants with opposing effects may suggest the presence of biological mechanisms that could support the beneficial effects of cannabis”, the researchers point out.

These new findings have several important clinical implications.

Firstly, this information may result in personalized care including preventative and interventional measures for high-risk individuals. This may include reducing cannabis use among individuals at high genetic risk for schizophrenia and bipolar disorder.

Secondly, future studies investigating the biological effects of the shared genetic variants may contribute to the development of more targeted treatment efforts.

Finally, the improved knowledge about genetic overlap can be used to help stratify patients for more specialized treatment plans.

About this genetics and mental health research news

Author: Press Office
Source: University of Oslo
Contact: Press Office – University of Oslo
Image: The image is credited to Neuroscience News

Original Research: Closed access.
The relationship between cannabis use, schizophrenia, and bipolar disorder: a genetically informed study” by Weiqiu Cheng et al. Lancet Psychiatry


The relationship between cannabis use, schizophrenia, and bipolar disorder: a genetically informed study


The relationship between psychotic disorders and cannabis use is heavily debated. Shared underlying genetic risk is one potential explanation. We investigated the genetic association between psychotic disorders (schizophrenia and bipolar disorder) and cannabis phenotypes (lifetime cannabis use and cannabis use disorder).


We used genome-wide association summary statistics from individuals with European ancestry from the Psychiatric Genomics Consortium, UK Biobank, and International Cannabis Consortium. We estimated heritability, polygenicity, and discoverability of each phenotype. We performed genome-wide and local genetic correlations. Shared loci were identified and mapped to genes, which were tested for functional enrichment. Shared genetic liabilities to psychotic disorders and cannabis phenotypes were explored using causal analyses and polygenic scores, using the Norwegian Thematically Organized Psychosis cohort.


Psychotic disorders were more heritable than cannabis phenotypes and more polygenic than cannabis use disorder. We observed positive genome-wide genetic correlations between psychotic disorders and cannabis phenotypes (range 0·22–0·35) with a mixture of positive and negative local genetic correlations. Three to 27 shared loci were identified for the psychotic disorder and cannabis phenotype pairs. Enrichment of mapped genes implicated neuronal and olfactory cells as well as drug–gene targets for nicotine, alcohol, and duloxetine.

Psychotic disorders showed a causal effect on cannabis phenotypes, and lifetime cannabis use had a causal effect on bipolar disorder. Of 2181 European participants from the Norwegian Thematically Organized Psychosis cohort applied in polygenic risk score analyses, 1060 (48·6%) were females and 1121 (51·4%) were males (mean age 33·1 years [SD 11·8]). 400 participants had bipolar disorder, 697 had schizophrenia, and 1044 were healthy controls.

Within this sample, polygenic scores for cannabis phenotypes predicted psychotic disorders independently and improved prediction beyond the polygenic score for the psychotic disorders.


A subgroup of individuals might have a high genetic risk of developing a psychotic disorder and using cannabis. This finding supports public health efforts to reduce cannabis use, particularly in individuals at high risk or patients with psychotic disorders. Identified shared loci and their functional implications could facilitate development of novel treatments.


US National Institutes of Health, the Research Council Norway, the South-East Regional Health Authority, Stiftelsen Kristian Gerhard Jebsen, EEA-RO-NO-2018–0535, European Union’s Horizon 2020 Research and Innovation Programme, the Marie Skłodowska-Curie Actions, and University of Oslo Life Science.

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  1. I’d like to see them spend half the time on gender dysphoria that they do on an herb humans have been using for thousands of years.

  2. Im going to disagree with the ridiculous science of this whole smoking cannabis while pregnant can cause psychological disorders. If it’s genetic then it’s just that Genetic. Cannabis has nothing to do with it. Alcohol is a depressent. So if genetically depression run in ur family, then more likely than not u may suffer from depression. So ingesting substances that cause worse depression would just be ridiculous. I have bipolar type 1 & schizoeffective disorder. I try to smoke marijuana daily to soothe the symptoms of my disorders. Cannabis has been the best thing to ever happen to me. Science tries to pacify the government. It’s just sad. Leave people to live their lives stop all the analysis crap. It’s BS

  3. My son has schizophrenia and here in the state of Washington Cannabis is legal however our court system has to follow federal law and my son, who had been smoking since, I am guessing, 15-16 had to stop for 2 months and when he did is when an episode occurred. He is on one med not sure which one he is 25 and has been fine since and smokes everyday and his life is going great I believe the withdrawal from smoking is what started the episode to start. I am sure you are aware that there can be drug induced onset and withdrawal as far as genetics my Aunt had schizophrenia it seemed to have skipped a generation for I had a nephew who was diagnosed schizophrenic as well.

    1. It’s a dangerous error in the reasoning of neuroscientist to have assumed that the majority of people are wired properly and that those who behave differently are somehow broken or defective. Humanity is not chattel. The more you try to force humanity into a box the more clear the box becomes and the more violently they rebel against it. Surely you know the tighter you squeeze the more grains of sand slip between your fingers…

  4. I agree with the article. All psychosis disorders are an emotional state, we must stop talking about mental and psychological problems and start talking about emotional problems.
    Alcohol, nicotine, drugs and some pharma drugs changes the way we FEEL.
    All our emotions are inherited, where else can they come from? No-one teaches us how to feel.
    If one of our parents suffered from depression or dependence on alcohol, there’s a 50% chance that we will, more than likely, inherit this craving.
    This is not an easy thing to face up to but if we do it explains so many things.

  5. Try e netting the open the open windows reality of the and the area of the others.

    1. If you think feelings are inherited,then all my ancestors must of thought you are retarded because I feel that you are.

  6. I’m interested on neurological brain mapping in ppl w/ resistant depression :
    Marijuana has been suggested & ketamine…
    Your opinion ?
    Thanking you kindly


    1. If I may insert an unsolicited opinion I’d like to quickly do so. I’m a Master’s of Psychiatric Nurse Practitioner student. My comment will be very long, but should address the normal questions everyone has about Ketamine.

      I have personally been investigating psychedelics blossoming role in my psychiatric field. We have been told at this time to PUSH psychedelics therapy with our patients. As well as to seek out this therapy ourselves to treat Secondary Trauma to ourselves, a type of trauma caused by listening to our patients’ trauma.

      Now that psychedelics have studies that have been completed, what we call Benchmark studies,we are beginning psychedelics therapy. Ketamine in particular is the best advance in the psychedelics since the creation of drugs that revolutionized current psychiatric practice fifty years ago.

      Personally, I had never taken a psychedelic in my life. I have worked very hard for many long years to advance my career to the point I have reached. I’ve never been interested in using substances to escape reality while potentially ruining my career and ll losing my license for even trying a psychedelics. And to be frank I was scared of them. I had never ‘tripped’ or in professional terms, I’ve had never had visual hallucinate or drug induced delusions.

      I began using ketamine for chronic pain last year. I’ve been a chronic pain patient for seven years, after shattering my pelvis while working with a patient. Believe it or not working in healthcare is dangerous. And my field is one of the MOST dangerous. Insurance does not like to pay for ketamine therapy, but they are more likely to not fight paying these claims if the treatment is for pain relief, not for anxiety or depression. I loved every day of my life in excruciating pain. On the pain scale I was at a 8-10, usually a 10. For to the opioid epidemic at no point was my pain pill strength or count number increased. Despite tolerance to the pills making them less and less effective. I hate these pills, because they run my life. I started out with a long acting pill, a short acting pill, and another for ‘break through pain’. Previous to ketamine therapy I had weaned myself off of all but the short acting pill. But the pain was still so bad I wished I wouldn’t wake up every night when I went to bed. I also fantasized about death regularly. Not that I wanted to die, I just wanted to stop the pain. When I started ketamine therapy, a therapy I not only did I not want, but as previously stated, I feared it.

      I can say with near certainty that ketamine saved my life. My passion rating fell to about 3-4 daily. My opioid consumption fell by 75%. And anxiety and depression I DIDN’T KNOW I EVEN HAD lifted for the first time in my nearly fifty years of life. I also lost my addiction to nicotine as a result of treatment. Ketamine is known to CURE addiction. And by that I mean addiction to ANY substance. You know what prescription drugs does that? Nothing, absolutely nothing else can do that.

      So traditional mental healthcare is you find a therapist that you see to talk about your life traumas with to process them. Hopefully, you ‘click’ with your therapist and feel you can talk openly with them. Hopefully, you don’t have transference and countertransference. Essentially, emotions that you and/or your therapist have, due to previous life events, that may discourage a productive therapeutic progression. Hopefully, you can REMEMBER your traumas to talk about them. And hopefully you CAN bring yourself to talk about the most painful traumas in your life. And lastly, hopefully you can make it to appointments regularly FOR YEARS. Getting time off work, because therapists aren’t open in the evenings or on weekends.

      Then often you’re put on a medication. Hopefully, you can afford the medication, you remember to take your pill every day (potentially for the rest of your life), and hopefully you can AFFORD your medication. Lastly, and most importantly, hopefully you don’t have an incredibly common side effect, which is the most frequent reason patients stop taking psychedelic medications. Hopefully, you don’t lose all ability to have sex.

      OR, ketamine therapy is not a therapy you speak during. If you can’t remember or can’t talk about your traumas NO PROBLEM. The average number of sessions you need is six. The most effective way to get ketamine therapy is to do a minimum two sessions per week, at least a day apart. So the entire amount of time dedicated to ketamine therapy is generally two to three weeks. You can be re-traumatized due to normal life events. So you may need a ‘touch up’ session down the road. Some people plan on a future session at at a certain time, like one session every year at a certain point, like maybe before Christmas to cut down on stress. Or maybe a session session three Anniversary of the day your child or your husband/wife/partner died.

      I know this was long, i hope you got through it. I know there’s a lot of uncertainty surrounding the new field of psychedelics therapy. But you too can look up studies to address your questions. Go to Google and type in your question, then follow it with what is called a Boolean operator. This is done by adding ‘ and .edu’. This alters your search to pull results that ideally are unbiased and peer reviewed. Obviously some studies are produced by someone very biased. I saw a study about how many millions of people overdose on Cannabis every year. *Pause for uproarious laughter* you cannot overdose on psychedelics. Some simple research shows this study was done by a preacher at a religious college.

      Currently, statistically, the biggest threat to both a doctor and a cop’s life is themselves. Suicide rates are very bad in those professions. Psychedelics are the cure.

      I’m including a study, just one, and I’m fully prepared for you to not read it. I wish we could just sit down and have coffee, and I could answer all your questions. But for now this is all I can do. Good luck and good mental health to you.

  7. The basic assumptions in this “study” are flawed from the outstart.
    The conclusions, that cannabis causes mental disorders through some sideways or backwards mechanism is ludicrous.
    This is clickbait garbage meant to generate breathless reporting on the news.

    1. Absolutely correct Michael! All mammals have an endocannabinoid system which maintains homeostasis within the body. We have CB receptors which react to the agonists found in herbs/plants such as hemp, cannabis, rosemary, oregano, etc. How embarrassing for those writing this crap load of lies!

      1. Of course a person who is genetically prone to develop psychoses probably should avoid psycho active substances. The fact is that humans and other animals are genetically prone to engage in pleasurable activities and using psycho active substances can be pleasurable to use for most people. What I would like to see are studies which reveal the interconnection between dream quality and the use of the various substances we may ingest while awake.

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