Is the grass greener? The link between cannabis and psychosis

Concern about cannabis use is not new: ordinances were passed in 8th-century Egypt prohibiting use of hemp drugs, transgressors being subject to tooth extraction!¹ In the 19th century, controversy over widespread cannabis use led to the Indian Hemp Drugs Commission, a large-scale investigation into the health effects (both physical and mental) of cannabis use. The Commission's wide-ranging report found that the relationship between cannabis and "mental injury" was complex, and criticised many witnesses for their obvious bias.² Social, moral and political agendas continue to influence both cannabis research and the "cannabis debate".³