Strong Genetic Component to Psychotic-Like Experiences with Cannabis

MedicalResearch.com Interview with:
Dr. Nicole Karcher, PhD
Post-doctoral scholar with the NIMH Training in Clinical Sciences fellowship
Department of Psychiatry
Washington University School of Medicine  

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: For over fifteen years, researchers have debated the role that cannabis use plays in the development of both psychotic disorders as well as subthreshold psychotic symptoms, such as psychotic-like experiences (PLEs). There is still a lack of consensus regarding the nature of the association between cannabis use and psychosis risk, with some research finding evidence for genetic overlap, while other research finds evidence for potentially causal pathways.

The current study examined data from twins and siblings from two different samples, the U.S.-based Human Connectome Project and the Australian Twin Registry, with a total of 4,674 participants. Overall, psychotic-like experiences were associated with three separate cannabis use variables [frequent (≥100 times) use, a Cannabis Use Disorder diagnosis, and current cannabis use]. Furthermore, the current research found evidence for both shared genetic and individual-specific contributions to the association between PLEs and these three cannabis use variables. More specifically, while the association between cannabis use and psychotic-like experiences was largely attributable to shared genetic factors, cannabis users were more likely to endorse PLEs in comparison to the relative who used cannabis less.  Continue reading