Does cannabis use cause psychosis ?
• There are a number of risk factors which are believed to contribute to the development of a psychosis, one of which is believed to be cannabis use • The peak age range during which people are more vulnerable to developing a psychosis (16-30 years of age) tends to be the same age range during which people tend to use cannabis • A very large study of 50,465 Swedish army conscripts determined their cannabis use at age 18 and followed those individuals for the next 15 years. Recruits who had tried cannabis by age 18 had 2.4 times the risk of being diagnosed with schizophrenia in the following 15 years than those who had never used cannabis. The risk increased if the conscript used greater quantities of cannabis However, of the conscripts who developed schizophrenia: • Most had never used cannabis and • Only 7.7 per cent were heavy cannabis users • Therefore, cannabis use is only one possible factor contributing to an increased risk of developing schizophrenia or other psychosis.
