- Scientists have discovered 35 ‘overlapping’ genes linking the two traits
- Cannabis may not cause schizophrenia – the illness could lead to the drug use
- Marijuana users are also more likely to be outgoing or take risks, the study said
- But experts have not ruled out cannabis contributing to the illness
People at high risk of schizophrenia are more likely to smoke cannabis, a study has found.
Scientists studied more than 180,000 people worldwide using data from DNA testing website 23andMe as well as UK health records and past studies.
They found 35 genes which influence whether people are ever likely to smoke marijuana.
And the same genes also affect how likely someone is to develop schizophrenia, showing that as the likelihood of one increases, the other does, too.
The illness could actually be driving people to use cannabis in order to cope, the researchers suggest, instead of the previously-held belief that the drug can directly cause the condition.
And similar genetic links mean people are also more likely to have extroverted personalities or indulge in risky behaviour – which could drive them to smoke pot.
But the study does not give any evidence to prove that smoking marijuana does not contribute to mental health problems.
People who are genetically more likely to get schizophrenia are also more likely to use cannabis, but the drug may not directly cause the condition, according to international research
The study was carried out by researchers at the QIMR Berghofer Institute in Brisbane, Radboud University in the Netherlands and Virginia Commonwealth University in the US.
Researchers used data from past scientific studies and medical records, as well as from the website 23andMe, which offers private DNA and ancestry testing by post.
They found what they called a ‘genetic overlap’ in people’s DNA.
The overlap revealed there are some genes which increase both someone’s chance of developing schizophrenia and their tendency to smoke cannabis.