An analysis of over 162 high-quality studies has found the link between cannabis and psychosis is weaker than previously estimated.
The study published in the journal Nature Mental Health, was conducted by a team at the University of Lausanne in Switzerland. Researchers analysed data from over 200,000 participants, aiming to combine results and understand the relationship between cannabis use and cannabis-associated psychotic symptoms (CAPS).
Individual studies report varying levels of CAPS among cannabis users, from as low as 1% to as high as 70%. However, the analysis found that only one in 200 cannabis users (0.5%) may experience psychotic symptoms such as hallucinations, delusions and paranoia.
The large-scale analysis took data from a wide range of studies, including observational research of recreational cannabis users, studies where THC was given to healthy volunteers, and studies assessing adverse events in individuals taking cannabis for medicinal use.
The rates of CAPS varied significantly across the different study types. Observational and experimental research reported higher rates of 19% and 21%, respectively, while medical cannabis studies reported a lower rate of between 1% and 2%.
The researchers stated that CAPS are reported at higher levels in observational studies of recreational users as symptoms are often recorded despite being short-lived. In contrast, medical studies would only record persistent ‘first-rank’ symptoms of psychosis as an adverse reaction, leading to the end of treatment.
The study found that young adults, women and those with pre-existing mental health conditions such as bipolar disorder were found to be more at risk of experiencing CAPS than others. The analysis also found that early and frequent cannabis exposure did not increase the risk of psychotic episodes. However, researchers warned that daily use could still increase the long-term risk of developing psychosis. “Some individuals appear to be particularly sensitive to the adverse acute effects of cannabis, notably young individuals with pre-existing mental health problems and individuals exposed to high levels of THC,” the study said.
Previous research has suggested that genetic factors could explain why some cannabis users develop psychosis while others do not. However, the analysis found no significant association with the genes COMT and AKT1, genes that have previously been implicated in the interaction between cannabis-related psychosis.
This story first appeared on leafie, view here
Author: Liam O’Dowd
