The study was part of a project conducted by the European Network of National Schizophrenia Networks Studying Gene-Environment Interactions , a consortium of research centres in 13 countries, including Brazil.
In the more recent study, the researchers analysed data for 409 people aged 16 to 64, including patients experiencing their first psychotic episode and community-based controls.
As well as the questionnaire on cannabis use, researchers measured various cytokines in plasma donated by the volunteers and calculated scores representing their systemic inflammatory profiles.
Fabiana Corsi-Zuelli, first author of the article, said: “Not everyone who uses cannabis develops psychosis.
“In a previous study conducted as part of my master’s research, we identified a correlation between plasma cytokines and the first psychotic episode.
The principal investigator for the project is Cristina Marta Del-Ben, Professor at FMRP-USP’s Department of Neurosciences and Behavioral Sciences.
In the multicentre study, which included European cities with varying levels and types of cannabis availability, we also found that the risk of psychosis is greater in users of stronger cannabis strains with a THC content or 10% of higher.” THC is the primary psychoactive constituent of cannabis or marijuana.