Understanding Cannabis-Linked Paranoia: Motives, Trauma, and Clinical Implications

Emerging research from King’s College London and the University of Bath sheds new light on the link between cannabis use and paranoia—especially when compounded by early-life trauma.^1,2

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A landmark study exploring data gathered from more than 3,389 adults (Cannabis & Me survey) identified a clear pattern: patients who turned to cannabis to treat themselves with anxiety, depression, or pain claimed a much larger amount of weekly THC usage alongside higher paranoia ratings than the people who merely consumed cannabis for recreational use.¹ The study notes that the use and potency of cannabis are increasing worldwide, and dependence and cannabis-induced psychosis are also greatly increasing as a result, especially in North America.^1,2

In a related analysis of the same dataset, it was found that 52% of respondents disclosed that they had been subjected to traumatic experiences during childhood, with the most common being emotional or physical abuse and household discord. Those individuals not only had significantly elevated paranoia scores, but this effect was also exacerbated by the consumption of cannabis.¹ Such a synergistic interaction makes a strong case that trauma and drug use co-occur to trigger negative mental health outcomes.

Giulia Trotta, PhD, lead author, noted, “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.”¹

The extensive survey data was supplemented with psychiatric research from Oxford University, which concerned the immediate effects of THC on paranoia. A carefully managed experiment on healthy volunteers found that among the group that was given a THC dose similar to that of one potent joint, 50% developed paranoid thoughts, in contrast with the placebo group, in which only 30% developed those thoughts.³ The increase in paranoia was associated with perceptual distortions and increased anxiety, not with memory impairment only.³

Professor Daniel Freeman notes, “Paranoia is excessive thinking that other people are trying to harm us… Many people have a few paranoid thoughts, and a few people have many paranoid thoughts.”³ He adds that even minor shifts in perception or worry can fuel paranoid thinking, evidencing how THC may exacerbate these tendencies.³

Patients who use cannabis for therapeutic purposes, especially those engaging in heavy or habitual use, may require closer monitoring for signs of paranoia or psychological distress. Screening for the history of traumatic events during childhood is also a must, as people with such backgrounds are likely to develop worse mental health conditions if they use cannabis. In addition, patient education on dosing is critical. Introducing the concept of tracking THC consumption in standardized units, similar to alcohol, could provide a practical framework to help patients manage intake responsibly. Finally, pharmacists can play a vital role in offering alternatives and support, guiding patients who self-medicate with cannabis for pain or anxiety toward safer, evidence-based therapies and appropriate referrals.

Recent evidence offers a more nuanced perspective that cannabis is not always harmless. The ways in which the drug is used, especially when an individual is self-medicating due to past trauma, may increase the likelihood of paranoia and mental health decline. THC itself can trigger or amplify paranoid ideation.

REFERENCES

1. Largest ever study into cannabis use investigates risk of paranoia and poor mental health in the general population. EurekAlert! Published August 26, 2025. https://www.eurekalert.org/news-releases/1095960

2. Spinazzola E, Degen H, Austin-Zimmerman I, et al. Are reasons for first using cannabis associated with subsequent cannabis consumption (standard THC units) and psychopathology? BMJ Mental Health. 2025;28(1). doi:10.1136/bmjment-2025-301810

3. How cannabis causes paranoia | University of Oxford. www.ox.ac.uk. https://www.ox.ac.uk/news/2014-07-16-how-cannabis-causes-paranoia