Schizophrenia and Marijuana Use Linked: Genes Increase a Person's Likelihood of Using Cannabis

If you're schizophrenic, you may be more likely to use marijuana. Scientists have discovered that genes that increase a person's risk of developing schizophrenia may also increase their likelihood of using cannabis.

Previous studies have actually identified a link between cannabis use and schizophrenia. But it isn't until now that the researchers have found whether this association is due to cannabis directly increasing the risk of the disorder.

Marijuana, or cannabis, is actually the most widely used illicit drug in the world. More interesting is the fact that its use is far higher among people with schizophrenia than among the general population. Schizophrenia impacts about one in 100 people, and people who use marijuana are about twice as likely to develop the disorder.

In order to better understand the relationship between this disorder and cannabis use, the researchers examined 2,082 individuals, 1,011 of whom had used cannabis. Each individual's genetic risk profile was measured in regards to schizophrenia.

So what did the scientists find? It turns out that people genetically pre-disposed to schizophrenia were more likely to use cannabis, and use it in greater quantities.

"We know that cannabis increases the risk of schizophrenia," said Robert Power, one of the researchers, in a news release. "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."

The study actually highlights the complex interactions between genes and environments. More specifically, it shows that cannabis use may be more likely given an individual's innate behavior and personality, which is, itself, influenced by genetics.

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

The findings are published in the journal Molecular Psychiatry.