New research shows that self-medicating with cannabis can lead to higher paranoia, anxiety, and depression—especially for those with childhood trauma.
Recreational users face fewer risks, but those coping with pain or distress tend to consume more THC and struggle more with mental health.
Rising Cannabis Use and Mental Health Concerns
A major study led by the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London, working with the University of Bath, has revealed that a person’s reasons for using cannabis can play a major role in whether they later develop paranoia.
As cannabis becomes stronger and more widely used across the globe, cases of dependence and cannabis-induced psychosis have been rising, with particularly sharp increases reported in North America. Drawing on data from Cannabis & Me (the largest survey of its type), two new studies have pinpointed important risk factors linked to the most severe forms of paranoia in people who use cannabis.
Exploring Motives Behind First Cannabis Use
The first study, published in BMJ Mental Health, examined how people’s initial reasons for using cannabis influenced their long-term patterns of use.
A total of 3389 adults, both current and former cannabis users aged 18 and above, completed a survey. They were asked about their motivations for starting and continuing cannabis use, how much they consumed each week in THC units, and their overall mental health.
The results revealed a clear pattern. Participants who first turned to cannabis as a way of coping with physical pain, anxiety, depression, or early psychotic symptoms scored significantly higher for paranoia.
By contrast, those who initially used cannabis out of curiosity, for enjoyment, or in a social setting with friends reported the lowest levels of paranoia and anxiety.
Expert Warnings on Cannabis and Mental Health
Dr. Edoardo Spinazzola, a Research Assistant at King’s IoPPN and the study’s first author, said, “Our study provides vital evidence on how the reason someone first starts using cannabis can dramatically impact their long-term health.
“This research suggests that using cannabis as a means to self-medicate physical or mental discomfort can have a negative impact on the levels of paranoia, anxiety, and depression. Most of these subgroups had average scores of depression and anxiety, which were above the threshold for referral to counselling.”
Measuring THC Consumption Patterns
Respondents were also asked to provide data on the frequency and strength of the cannabis they were using so that researchers could track their average weekly consumption of Tetrahydrocannabinol (THC) – the principal psychoactive component of cannabis.
The researchers found that the average respondent consumed 206 units of THC a week. This might equate to roughly 10-17 ‘joints’ per week, if the user was consuming an expected 20 percent THC content that is standard for the most common types of cannabis available in London.
However, respondents who started using cannabis to help with their anxiety, depression, or in cases where they started due to others in their household who were already using cannabis, reported on average 248, 254.7, and 286.9 average weekly THC units, respectively.
Comparing Cannabis to Alcohol Units
Professor Tom Freeman, Director of the Addiction and Mental Health Group at the University of Bath and one of the study’s authors, said, “A key finding of our study is that people who first used cannabis to manage anxiety or depression, or because a family member was using it, showed higher levels of cannabis use overall.
“In the future, standard THC units could be used in a similar way to alcohol units – for example, to help people to track their cannabis consumption and better manage its effects on their health.”
Childhood Trauma, Paranoia, and Cannabis Use
In a separate study, published in Psychological Medicine, researchers explored the relationship between childhood trauma, paranoia, and cannabis use.
Researchers used the same data set from the Cannabis & Me survey, with just over half of respondents (52 percent) reporting experience of some form of trauma.
Types of Abuse and THC Consumption
Analysis established that respondents who had been exposed to trauma as children reported higher average levels of paranoia compared to those who hadn’t, with physical and emotional abuse emerging as the strongest predictors.
Researchers also explored the relationship between childhood trauma and weekly THC consumption. Respondents who reported experiencing sexual abuse had a markedly higher weekly intake of THC, closely followed by those who reported experiencing emotional and physical abuse.
Finally, the researchers confirmed that the strong association between childhood trauma and paranoia is further exacerbated by cannabis use, but is affected by the different types of trauma experienced. Respondents who said they had experienced emotional abuse or household discord[1] were strongly associated with increased THC consumption and paranoia scores. Respondents reporting bullying, physical abuse, sexual abuse, physical neglect, and emotional neglect, on the other hand, did not show the same effects.
Clinical Implications of the Findings
Dr. Giulia Trotta, a Consultant Psychiatrist and Researcher at King’s IoPPN and the study’s first author, said, “This comprehensive study is the first to explore the interplay between childhood trauma, paranoia, and cannabis use among cannabis users from the general population.
“We have not only established a clear association between trauma and future paranoia, but also that cannabis use can further exacerbate the effects of this, depending on what form the trauma takes.
“Our findings will have clear implications for clinical practice as they highlight the importance of early screening for trauma exposure in individuals presenting with paranoia.”
Policy Concerns Around Legalization and Risks
Professor Marta Di Forti, Professor of Drug use, Genetics and Psychosis at King’s IoPPN, Clinical Lead at the South London and Maudsley NHS Foundation Trust’s Cannabis Clinic for Patients with Psychosis, and the senior author on both studies, said, “There is extensive national and international debate about the legality and safety of cannabis use.
“My experience in the clinic tells me that there are groups of people who start to use cannabis as a means of coping with physical and emotional pain. My research has confirmed that this is not without significant further risk to their health and wellbeing, and policy makers across the world should be mindful of the impact that legalization, without adequate public education and health support, could have on both the individual, as well as on healthcare systems more broadly.”
Notes
- Household discord refers to living in a space where there is disharmony, conflict, or disagreement within a family unit.
References:
“Are reasons for first using cannabis associated with subsequent cannabis consumption (standard THC units) and psychopathology?” by Edoardo Spinazzola, Hannah Degen, Isabelle Austin-Zimmerman, Giulia Trotta, Edward Chesney, Zhikun Li, Luis Alameda, Bok Man Leung, Yifei Lang, Andrea Quattrone, Diego Quattrone, Erika Castrignanò, Kim Wolff, Robin Murray, Tom P Freeman and Marta Di Forti, 26 August 2025, BMJ Mental Health.
DOI: 10.1136/bmjment-2025-301810
“The impact of childhood trauma and cannabis use on paranoia: a structural equation model approach” by Giulia Trotta, Edoardo Spinazzola, Hannah Degen, Zhikun Li, Isabelle Austin-Zimmerman, Bok Man Leung, Yifei Lang, Victoria Rodriguez, Monica Aas, Lucia Sideli, Kim Wolff, Tom P. Freeman, Robin M. Murray, Chloe C. Y. Wong, Luis Alameda and Marta Di Forti, 8 August 2025, Psychological Medicine.
DOI: 10.1017/S0033291725101190
Cannabis & Me was possible thanks to funding from the Medical Research Council (MRC).
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.
3 Comments
When will researchers realize that there are DIFFERENT TYPES OF CANNABIS!?!? Indica varieties produce FAR LESS “paranoia” than Sativa cultivars. They need to look at the overall distribution of cannabinoids and terpenes.
You wrote ” Indica varieties produce FAR LESS “paranoia” than Sativa cultivars.”
I noticed the “Far Less” and added an E to make it Fear Less which would be nice. What is it about Mary Jane that it can produce such terror in some people? I have seen the awful face of the Man in the Sky and I am still reluctant to look up into the heavens after 40 odd years though other ‘sighting’, initially scarey, they usually turned out okay if followed through. I can’t be the only one having these amazing experiences.
I’m on a sabbatical for 6 months or so after an intense conversation with Khrisna I think that’s who it was. His English was perfect just like most of the Indians I know. Better than mine and I’m English/Welsh/Scottish/Breton/Scandanavian or so I believe. And diabetic just like everybody else.
whenever I get a bit paranoid or anxious I remind myself it is the dope talking and lean in to it – works for me – it does help being retired and away from the a’holes who generally run large organisations …