Scientists have found a link between genes that increase the risk of schizophrenia and the likelihood of using cannabis.
Cannabis is the most commonly used illicit drug worldwide, say the researchers, led by Mr Robert Power at King’s College London, UK. “With debate surrounding the legalisation and control of use, investigating its health risks has become a pressing area of research.”
The team focused on the established link between cannabis use and schizophrenia. They state that “considerable evidence implicates cannabis use as a component cause of schizophrenia”, but it is still unclear whether this is due to cannabis directly raising the risk, or whether the same genes increase both risks.
They used figures on 2,082 healthy people whose “genetic risk profile” was measured. About half had used cannabis. Their gene profile showed the number of genes related to schizophrenia that each individual carried.
“We show an association between an individual’s burden of schizophrenia risk alleles and use of cannabis,” report the authors in yesterday’s (24 June) issue of Molecular Psychiatry.
“This was significant both for comparing those who have ever versus never used cannabis, and for quantity of use within users,” they add. “These findings suggest that part of the association between schizophrenia and cannabis is due to a shared genetic aetiology.”
Mr Power said: “We know that cannabis increases the risk of schizophrenia. Our study certainly does not rule this out, but it suggests that there is likely to be an association in the other direction as well – that a pre-disposition to schizophrenia also increases your likelihood of cannabis use.”
Power, R. A. et al. Genetic predisposition to schizophrenia associated with increased use of cannabis. Molecular Psychiatry 24 June 2014 doi:10.1038/mp.2014.51
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