Jun 24, 2014 09:39 AM EDT By J Baulkman, UniversityHerald Reporter

Schizophrenia and Cannabis may share common genes, according to a recent study.

Researchers from King's College London and the Queensland Institute of Medical Research in Australia discovered that genes that increase the risk of developing schizophrenia may also increase the likelihood of using cannabis. The new results suggest that part of this association is due to common genes, but do not rule out a causal relationship between cannabis use and schizophrenia risk.

"Studies have consistently shown a link between cannabis use and schizophrenia," Robert Power, lead author of the study, said in a statement. "We wanted to explore whether this is because of a direct cause and effect, or whether there may be shared genes which predispose individuals to both cannabis use and schizophrenia."

Cannabis is the most widely used illicit drug in the world, and its use is higher amongst people with schizophrenia than in the general population. Schizophrenia affects approximately 1 in 100 people and people who use cannabis are about twice as likely to develop the disorder.

For the study, researchers collected information from 2,082 people of whom 1,011 had used cannabis. Researchers measured each individual's "genetic risk profile" -- that is, the number of genes related to schizophrenia each individual carried.

The researchers found that people genetically pre-disposed to schizophrenia were more likely to use cannabis, and use it in greater quantities than those who did not possess schizophrenia risk genes.

"We know that cannabis increases the risk of schizophrenia," Power said. "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 said the study 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.

"This is an important finding to consider when calculating the economic and health impact of cannabis," he said.

The findings were recently published in Molecular Psychiatry.

See Now: Covert Team Inside Newsweek Revealed as Key Players in False Human Trafficking Lawsuit