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A large-scale genetic study found that some of the same genes associated with the use of cannabis are also associated with certain personality types and psychiatric conditions. The study was onducted by a team of scientists who are part of the International Cannabis Consortium.
Researchers used data from the UK Biobank, association results from 23andMe customers who consented to participate in research as well as data from individuals in 16 other smaller study cohorts. In all the researchers looked at data from more than 180,000 people for this study. The researchers found that people with schizophrenia are also more likely to use cannabis
According to the study author, Jacqueline Vink of Radboud University, and the study’s lead author, the study identified 35 different genes associated with cannabis use with the strongest associations in the gene CADM2. CADM2 has already been associated with risky behaviour, personality and alcohol use.
For this study, the researchers were able to look across more than a million genetic variants that helped to explain approximately 11 percent of the differences in cannabis use between people. The study found a genetic overlap between cannabis use and the use of tobacco and alcohol.
There was a similar overlap between cannabis use and personality types that were prone to more risky behaviour or were more extraverted. This means that genetic variants impacting cannabis use partially impact other psychological or psychiatric features as well.
The study also showed genetic overlap between cannabis use and the risk of schizophrenia, previous studies have shown that cannabis use and schizophrenia are associated with each other. The study showed that people with a vulnerability to develop schizophrenia are at increased risk of using cannabis.
The researchers used an analysis technique called “Mendelian randomisation” to show a causal relationship between schizophrenia and an increased risk of cannabis use. This may indicate that people with schizophrenia use cannabis as a form of self-medication. However, the researchers cannot exclude a reverse cause-and-effect relationship, meaning that cannabis use could contribute to the risk of schizophrenia.