Researchers at King's College London believe they have discovered a genetic link between schizophrenia and marijuana use.


According to the study, published in Molecular Psychiatry on Tuesday, "there may be shared genes which predispose individuals to both cannabis use and schizophrenia."

The study's lead author, Robert Power, said that "people who are at risk for schizophrenia are more likely to use cannabis, and in greater quantities."

He stressed that there is no evidence that using marijuana actually triggers schizophrenia, but acknowledged that individuals with schizophrenia are more vulnerable to "the most common symptoms of schizophrenia -- delusions and auditory hallucinations."

Previous studies had shown that individuals who smoke marijuana during the early stages of schizophrenia undergo more thorough brain modifications, which suggested a causal connection between marijuana use and the psychiatric illness.

But Power's study indicates that the relationship may be far more complex -- that it may consist of non-causal, but overlapping, genetic predispositions.

"Our study," Power said, "highlights the complex interactions between genes and environments when we talk about cannabis as a risk factor for schizophrenia. Certain environmental risks, such as cannabis use, may be more likely given an individual's innate behavior and personality, itself influenced by their genetic make-up."

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