Largest Study to Date Links Cannabis Use to Increased Risk of Paranoia and Mental Health Issues

A groundbreaking research initiative from King's College London, in collaboration with the University of Bath, has revealed crucial insights into how the motivations behind cannabis use may influence mental health outcomes. The study, based on data from the comprehensive Cannabis & Me survey—the largest of its kind—indicates that the reasons individuals start using cannabis significantly impact their risk of developing paranoia and other mental health disorders.

Recent trends have shown a worldwide increase in cannabis consumption and potency, correlating with rising cases of dependence and psychosis, particularly in North America. The research uncovered key factors associated with severe paranoia among cannabis users. One major finding was that individuals who began using cannabis to self-medicate factors like physical pain, anxiety, depression, or minor psychotic symptoms exhibited higher paranoia scores than those who tried cannabis purely for recreation or curiosity.

The study surveyed 3,389 adults, capturing data on their initial motivations for using cannabis, their weekly THC consumption, and various mental health indicators. Results showed that users who resorted to cannabis for medical reasons or emotional distress tended to consume larger quantities, averaging around 248 to 287 units of THC weekly, compared to about 206 units for recreational users.

Further analysis from another study published in Psychological Medicine examined the impact of childhood trauma. It found that individuals with histories of emotional or physical abuse, or sexual trauma, reported higher paranoia levels and consumed more THC weekly. The interaction between trauma, cannabis use, and paranoia highlights a vulnerable subgroup that may be at increased risk due to their early life experiences.

Experts emphasize that these findings underscore the importance of considering individual motivations and histories when addressing cannabis use and mental health. Dr. Giulia Trotta from King's IoPPN explained that childhood trauma can amplify the effects of cannabis on paranoia, emphasizing the need for early trauma screening in clinical settings. Professor Marta Di Forti added that as cannabis legalization spreads, there should be adequate public education and health support systems in place to mitigate associated risks.

Overall, the research advocates for greater awareness of how motivations and personal history influence the potential for cannabis to impact mental health, especially in vulnerable populations. Policy makers and healthcare providers are urged to consider these factors in their strategies to manage cannabis-related health issues.

Source: https://medicalxpress.com/news/2025-08-largest-cannabis-paranoia-poor-mental.html