Review shows that cannabis use is a risk factor for schizophrenia

Public health researchers in the Netherlands now believe that there is “converging evidence” to show that using cannabis is a risk factor for schizophrenia.

Researchers from the Netherlands Institute of Mental Health and Addiction warn that cannabis approximately doubles the risk of schizophrenia and that the risk increases in proportion to the amount of the drug used.

The researchers draw their conclusions from a review of five longitudinal studies recently published in four medical journals, including the British Medical Journal (Nederlands Tijdschrift voor Geneeskunde 2003;44:2178-83).

Data from these studies, which were …