New research, published in the journal Nature Mental Health, has revealed that people with cannabis use disorder face a significantly greater risk of developing psychiatric conditions such as schizophrenia, bipolar disorder, and major depression. The findings come as cannabis use rises globally, adding urgency to the debate about the mental health impacts of cannabis use and dependence.
The study, based on large-scale genetic analyses, distinguishes between casual cannabis use and cannabis use disorder. While both are common, their links to mental health are not the same. Casual cannabis use was found to have relatively weaker genetic connections to psychiatric disorders. In contrast, cannabis use disorder showed strong shared genetic factors with conditions like attention deficit hyperactivity disorder, major depressive disorder, and schizophrenia. This distinction highlights that the severity and pattern of cannabis consumption matter greatly when considering mental health risks.
Researchers used advanced genetic techniques to explore the relationship between cannabis use, cannabis use disorder, and mental health. The analysis included over a million participants from different studies and focused on how genetic markers tied to cannabis traits overlap with those linked to psychiatric disorders. The study identified specific genetic regions and variants that are associated with both cannabis use disorder and mental illnesses, offering new clues about biological pathways that may drive these connections.
The research team found evidence that cannabis use disorder and several psychiatric conditions influence each other in both directions. For example, people with genetic risk factors for cannabis use disorder were more likely to develop schizophrenia or depression. Conversely, individuals with genetic risks for these psychiatric conditions were more likely to progress from casual cannabis use to cannabis use disorder. The genetic overlap was most pronounced for cannabis use disorder, not for casual use, suggesting that problematic use rather than occasional consumption is driving the stronger mental health risks.
One notable finding was the shared genetic signature between cannabis use disorder and schizophrenia at specific locations in the genome. This supports earlier suggestions that heavy cannabis use may increase the risk of psychotic disorders. The researchers also highlighted that cannabis use disorder shares genetic traits with other substance dependencies, raising concerns about combined risks for vulnerable individuals.
While cannabis is sometimes promoted as a treatment for conditions like post-traumatic stress disorder, the study’s results call this into question. The researchers found no evidence that genetic risk for cannabis use or dependence protects against psychiatric disorders. Instead, the data point to a higher likelihood of co-occurring mental health issues. The findings add weight to calls for cautious and evidence-based approaches to cannabis legalisation and medical use.
These results contribute to a growing body of evidence about the complex relationship between cannabis and mental health. As cannabis becomes more widely accepted and accessible, understanding these risks is essential to protect public well-being and inform health policy decisions.
