Does the relationship between cannabis and psychosis become more obvious once somebodys had a psychotic episode?
Yes, once you have been psychotic then your dopamine receptors are sensitised and a number of factors can trigger off the psychosis again and it’s quite common that people who have been psychotic, who are partially recovered, for example in our unit, where somebody gets better we say well, why don’t you go out for the evening, meet your friends, they come back and the next morning they are psychotic again and if we say, well did you have a joint and they say yes, they are really surprised it could be just one joint. They say, well it used to be that I smoked every day and I didn’t go psychotic, once you have de-sensitised your dopamine system it can be sort of triggered off relatively easily. Some people have compared the influence of cannabis on mental health and the influence of tobacco on lung cancer, do you think that is a fair comparison? I think it’s perhaps more like alcohol actually than smoking, because cigarette smoking account for nearly all of lung cancer, whereas cannabis
