Amina Manzoor: Not either this study can conclude that cannabis leads to psychosis

Whether cannabis increases risk of psychotic diseases, for example schizophrenia, is a debated issue. Already in the 1980s, suggests a Swedish study of conscripts men that there was a connection between using cannabis at a young age and a later risk for schizophrenia, with a higher risk of högkonsumenter. Recent studies have also found a link, but these studies have not been able to conclude that it is actually cannabis causes psychotic disorders. It is a complex issue that is difficult to get answers on. There are few who actually get a schizofrenidiagnos, and it could be something else behind it. For example, these people have an increased risk from the outset and cannabis to be one of the factors to psykossjukdomen. The problem is that it is difficult to know in advance who is vulnerable.

– It is a so-called case-control study from eleven locations in Europe, including London and Amsterdam, and one in Brazil. The study, published in Lancet Psychiatry, involved 901 patients who have had a psychosis for the first time. The researchers asked these people about their habits, including cannabis use, and compared the responses with a control group of 1.237 healthy people. The study suggested that the who used cannabis daily had a significantly increased risk for psychosis. Even the one that used the stronger cannabis, which contained at least ten per cent of the psychoactive ingredient THC, appeared to have an increased risk for psychosis.

But not this study can establish a causal link, i.e. that it is cannabis use, which leads to psykoserna. However, the strengthens of this study, the relationship, and also that it can be a dosfråga.

– It may not be possible to get a definitive answer on the question if it actually is cannabis use increases the risk for psychotic diseases, even if the relationship has been seen in many studies. But it is an important question, because more and more states legalizes cannabis or avkriminaliserar the use of cannabis, which can increase the use. It has also become more prevalent with cannabis with higher doses of THC. According to another study, the strength of the incision increased from 8.9% to 17.1 in Europe and the united states in the last ten years. It can be an important task for the health service to identify people at risk and try to reduce the use of cannabis.