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Cannabis (Marijuana) Causes Psychosis

Updated: May 7

Cannabis and its by-products, specifically with high THC levels, can impact executive cognitive functioning and one’s propensity to develop anxiety/depression/bipolar during and after use and, in most individuals, schizophrenia.

Shalmalee Gadgil


weed causes psychosis
Marijuana (Cannabis) Plant

Cannabis use is a risk factor for developing a mental health condition or making an existing one worse. It may cause psychosis and other symptoms that affect a person’s mood and cognitive function. Its use, specifically of high-potency products [high in delta-9-tetrahydrocannabinol (THC)], accelerates the development and exacerbation of mental illness.

Many factors—such as the amount of drug consumed, the frequency of use, the potency (THC content) of any type of cannabis product, and a person’s age at first use—have been shown to influence the relationship between cannabis use and mental health deterioration. Similarly, many factors influence mental health—such as genes, trauma, stress, and environmental vulnerabilities. The risk is higher particularly if they have a genetic predisposition to the condition.

smoking up (weed, hash) causes psychosis

Symptoms such as paranoia, anxiety, or psychosis may be present during the initial stage of intoxication. Impaired coordination and learning, sleep problems, and executive dysfunction are among the effects that can last longer and may be permanent if left untreated.

Nicotinic receptors and cannabinoid receptors are not in the brain for smoking tobacco or marijuana; they are endogenous receptors that support specific functions (such as acetylcholine) when appropriate. When cannabis is smoked or ingested, THC and CBD bind to cannabinoid receptors and tap into endogenous receptors with much more potency – your endogenous receptors are out-competed.

These cannabis strains reduce the activity of the prefrontal cortex and induce relaxation and sedative effects but also lead to profound defects in short-term memory because they reduce the electrical activity of the hippocampus. There are no predictors of what your reaction will be to a given strain (e.g., whether you experience relaxation or paranoia).

Users exhibit a decrease in gray matter (GM) volume in the medial temporal cortex, temporal pole, parahippocampal gyrus, left insula, and orbitofrontal cortex. – risks include reduced cognitive executive functioning (movement, memory, attention, and emotions), development of depression, anxiety, psychotic features, schizophrenia, and inability to balance mood.

Smoking cannabis also increases prolactin levels (especially in those who smoke more than twice per week); dopamine and prolactin are mutually inhibitory – this is important in sexual arousal which will be suppressed if prolactin is elevated with cannabis use. It affects fertility as well: THC (not CBD) is inhibitory for gonadotropin-releasing hormone which ultimately reduces testosterone in men, and ovarian health in women.


Just because marijuana is legal in some places doesn't mean it is safe -

Some of the highest use of cannabis is among youth 16-24 (working or students) – this is concerning because it leads to a higher likelihood of developing depression, anxiety, or psychosis later in life because the grey matter is thinning out while the brain is still developing. This basically means the brain's capacity will be permanently stunted in the functional aspects of movement, memory, attention, emotions, and reality perception.

Early warning signs to look out for Psychosis:

  • a worrying decline in school grades or work performance

  • difficulty concentrating or thinking clearly

  • feeling suspicious or uneasy around others

  • a decline in personal hygiene or self-care

  • spending much more time alone than usual

  • a lack of feelings or very strong, inappropriate emotions

Anyone who experiences any symptoms should speak with a healthcare professional as soon as possible. Early treatment can help improve outcomes and recovery.

Some (not all) recovery of brain function can be restored: focus on behaviours that increase brain health and take precautions for future issues that may arise even after stopping the intake of cannabis.



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  3. HALL, W., & DEGENHARDT, L. (2008). Cannabis use and the risk of developing a psychotic disorder. World Psychiatry, 7(2), 68-71. doi: 10.1002/j.2051-5545.2008.tb00158.x

  4. Di Forti, M., Morgan, C., Dazzan, P., Pariante, C., Mondelli, V., & Marques, T. et al. (2009). High-potency cannabis and the risk of psychosis. British Journal Of Psychiatry, 195(6), 488-491. doi: 10.1192/bjp.bp.109.064220

  5. Episode 92: The Effects Of Cannabis (Marijuana) On The Brain & Body | Huberman Lab • Podcast Notes. (2022). Retrieved 3 May 2023, from

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  7. Vogel, A., Pearson-Dennett, V., Magee, M., Wilcox, R., Esterman, A., & Thewlis, D. et al. (2021). Adults with a history of recreational cannabis use have altered speech production. Drug And Alcohol Dependence, 227, 108963. doi: 10.1016/j.drugalcdep.2021.108963

  8. Androvicova, R., Horacek, J., Tintera, J., Hlinka, J., Rydlo, J., & Jezova, D. et al. (2017). Individual prolactin reactivity modulates response of nucleus accumbens to erotic stimuli during acute cannabis intoxication: an fMRI pilot study. Psychopharmacology, 234(13), 1933-1943. doi: 10.1007/s00213-017-4601-1

  9. Owens, M., Albaugh, M., Allgaier, N., Yuan, D., Robert, G., & Cupertino, R. et al. (2022). Bayesian causal network modeling suggests adolescent cannabis use accelerates prefrontal cortical thinning. Translational Psychiatry, 12(1). doi: 10.1038/s41398-022-01956-4

  10. Patrilli, K. et al. (2022) Association of Cannabis Potency with mental ill health and addiction: A systematic review, Available at: (Accessed: May 7, 2023).

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