In a large-scale genetic study, researchers found that some of the same genes linked to the use of cannabis are also linked to certain personality types and schizophrenia.
The study was conducted by a team of scientists who are part of the International Cannabis Consortium. It is the largest to date genetic study to look at the use of cannabis.
In the study, the 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.
They were able to look across more than a million genetic variants that together helped to explain approximately 11 percent of the differences in cannabis use between people.
In all the researchers looked at data from more than 180,000 people.
The study identified 35 different genes associated with cannabis use with the strongest associations in the gene CADM2.
The researchers also found that people with schizophrenia are also more likely to use cannabis.
CADM2 has already been linked to risky behavior, personality and alcohol use.
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 behavior or were more extroverted.
This means that genetic variants impacting cannabis use partially impact other psychological or psychiatric features as well.
The study also showed a genetic overlap between cannabis use and the risk of schizophrenia.
The team suggests that that is not a big surprise, because previous studies have often shown that cannabis use and schizophrenia are associated with each other.
However, they also studied whether this association is causal.
The researchers used an analysis technique called “Mendelian randomization” to show a causal relationship between schizophrenia and an increased risk of cannabis use.
The finding showed that people with a vulnerability to develop schizophrenia are at increased risk of using cannabis.
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.
Their next project is to explore which genes play a role in the frequency of cannabis use and the amount of cannabis used.
Jacqueline Vink at Radboud University is the study’s lead author.
The research is published in Nature Neuroscience.
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Source: Nature Neuroscience.