Cannabis and mental health

There has been a lot of media attention, in the last few months, on the relationship between cannabis and psychosis. The controversy has been fuelled by the government's decision to declassify the drug as well as the continued debate about whether or not the drug should be legalised. This article is not about the issue of the rights and wrongs of ingesting different substances. It is just to point out the current health risks associated with Cannabis which are often clouded in the current debate. For instance, how many people know the following: 1. Cannabis contains more tar than tobacco, and has a higher concentration of carcinogens (cancer-causing agents). 2. A recent study by the British Lung Foundation found that just three cannabis joints a day cause the same damage as 20 cigarettes. 3. Frequent use of cannabis can cut a man's sperm count and suppress ovulation in women. 4. Some people begin to feel tired all the time and can't seem to get motivated. So what about the psychological impact of smoking cannabis? It used to be thought that the high numbers of psychotic patients taking cannabis could be explained because they used it to alleviate their symptoms (The Self-Medication Theory). However, Professor Robin Murray, from the Institute of Psychiatry in London, in reviewing research into cannabis consumption and mental disorder, concludes that there is growing evidence that cannabis causes psychosis. Indeed, a recent study published in the British Medical Journal 1 concluded that Cannabis use moderately increases the risk of psychotic symptoms in young people but has a much stronger effect in those with evidence of predisposition for psychosis. It should be remembered that Cannabis is a depressant drug with hallucinogenic properties and so if you are feeling anxious, depressed or paranoid – smoking pot could emphasise these feelings Smoking a spliff makes some people happy and relaxed but just because you know people who appear to be happy smokers it doesn't mean that they are. More importantly, it doesn't mean that it will be OK for you. So my advice is, if you do have a history of mental health problems you should think very carefully about getting stoned. Prospective cohort study of cannabis use, predisposition for psychosis, and psychotic symptoms in young people BMJ, Jan 2005; 330: 11.