Cannabis does not cause schizophrenia according to a study by Harvard University

A new study conducted at Harvard University can help rule out concerns about the link between cannabis use and schizophrenia. While many still debate the possibility that cannabis can cause schizophrenia, researchers at Harvard Medical School say that “even lack conclusive evidence that cannabis can cause psychosis”.

Their latest study, published last week in the journal Schizophrenia Research, adds importance to the role of genetic factors in schizophrenia, and claims that cannabis itself not only increases the risk of developing it.

“In summary, we conclude saying that cannabis by itself does not cause psychosis. In genetically susceptible individuals, while cannabis can modify the disease onset, severity and treatment outcome, according to this study there is no evidence that it can be the cause of psychosis.

“The team, led by Professor of Psychiatry at Harvard Medical School Dr. Lynn DeLisi, compared the family histories of 108 schizophrenic patients and 171 individuals without schizophrenia to determine whether cannabis use was a factor in the development of the disorder. They found that a family history of schizophrenia increases the risk of developing schizophrenia, regardless of whether or not individual consumption of cannabis.

The authors concluded that “the results of this study suggest that having more family-morbid risk for schizophrenia may be the fundamental basis for the disorder in cannabis and cannabis not in itself”.