What weed can you smoke for schizophrenia

Study: smoking weed can trigger schizophrenia

Lausanne - Epidemiological data spanning over 40 years has provided evidence that there is a link between cannabis use and the risk of schizophrenia. So far, however, no study has been able to prove that smoking weed can also be directly responsible for the occurrence of the disease.

This has now been achieved with a new study in which the University Hospital Lausanne (CHUV) was involved. The study is based on a method known as "Mendelian randomization". This allows the influence of a risk factor - such as cannabis use - on the occurrence of diseases - in this case schizophrenia - to be examined.

With this method, false conclusions can be avoided, for example that the effect is mistakenly assumed to be the cause - for example that an increased risk of schizophrenia could be the reason for increased cannabis use. The trick is to use genetic markers that are statistically strongly related to the risk factor (cannabis use).

Genetic markers

Genetic markers are innate and are randomly distributed in the population. They are also not influenced by environmental factors, such as the family environment or the socio-economic situation, explains first author Julien Vaucher from the CHUV.

The scientists relied on data from a publication from 2016 that showed a connection between certain gene variants and cannabis use in 32,000 study participants. The same genetic markers were then searched for in a separate data set containing genetic information from 34,000 patients and 45,000 healthy individuals.

By combining this information from two separate sources, the researchers concluded that cannabis use was associated with a 37 percent increased risk of schizophrenia. Earlier observational studies had shown similar numbers. In addition, the relationship is not influenced by other factors, for example tobacco consumption.

Cannabis the most widely used illegal drug

"These robust results complement the numerous studies in this area and show that the link between cannabis use and an increased risk of schizophrenia is a causal one," emphasizes Vaucher. They are also important for public health to inform about the risks of smoking weed.

Precisely because this substance is experiencing a wave of liberalization and is increasingly being used for therapeutic purposes, a precise understanding of the mechanisms of action is required. Further studies could make it possible, for example, to formulate warnings for groups at high risk for schizophrenia or other disorders, according to the Lausanne expert.

However, the method used in the study did not allow the risk to be determined depending on the amount consumed, the type of cannabis, the form of administration or the age of the users, as the researcher emphasizes.

Cannabis is the most widespread illicit drug, with an estimated 182 million users in 2013. Other studies have already shown impaired signal transmission in the nervous system that is linked to the development of psychotic disorders. In addition, an influence on the maturation of the cerebral cortex was observed in adolescents. (APA, sda, January 24, 2017)