BRISTOL, England, Oct. 26 (UPI) -- British researchers say focusing on a relationship between marijuana use and risk of schizophrenia may be misguided.
The study, published in the journal Addiction, calls into question last year's reclassifying of marijuana from a class C to a class B drug by British officials, concerned, in part, about marijuana raising schizophrenia risk in young people.
Researchers at the University of Bristol and the London School of Hygiene and Tropical Medicine analyzed numbers of users, the risk of developing schizophrenia and the risk of marijuana use causing schizophrenia and found it would be necessary to stop 2,800 young men who are heavy marijuana users or in young women, 5,000 heavy users, to prevent a single case of schizophrenia.
Among light marijuana users, those numbers rise to more than 10,000 young men and nearly 30,000 young women to prevent one case of schizophrenia.
"Our research cannot resolve the question whether marijuana causes schizophrenia, but does show that many people need to give up marijuana in order to have an impact on the number of people with schizophrenia," Matt Hickman of Bristol says in a statement. "The likely impact of re-classifying cannabis in the U.K. on schizophrenia or psychosis incidence is very uncertain."