The most nostalgic of the 1968 emotionally scarred generation still believe that there is no association between cannabis and psychosis.

Some will even suggest that cannabis smoking is preferable to drinking alcohol. This week a leading police officer advanced the theory on radio that crushing cannabis smoking in a district was detrimental to both the individual’s health and to the law and order within the community. He said that in his experience the amount of cocaine taken in any one area is inversely proportional to the amount of cannabis used. Come down hard on the cannabis users and the result could be that there would be a cocaine problem.

Doctors who have been dealing with the ill effects of cannabis smoking were therefore relieved to read in the BMJ about a recent study of cannabis use, and its ability to precipitate psychotic symptoms in young people, especially if they had already shown symptoms which suggested a predisposition to psychiatric problems. Most medical practices have had patients who were young, bright and amusingly bizarre who appeared to have a good future awaiting them, only to have it dashed once they started to smoke marijuana.

There was a relationship between the amount of cannabis smoked and the likelihood that the user would develop psychotic symptoms. The more someone smoked the greater the likelihood of psychotic symptoms. These symptoms are not always so serious as to be described as a psychotic breakdown, but even lesser symptoms can affect the ability of a young person to do their job properly or to make good social relationships.

The research published in the BMJ was carried out by psychiatrists in Maastricht in the Netherlands. They took great trouble to adjust the findings for any confounding factors, such as concurrent use of alcohol, cigarettes, or other drugs, which might have given a bias to results.

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