乌鸦传媒

Cannabis use preceded onset of psychosis symptoms in teens more often than the reverse, according to researchers analyzing data from a longitudinal study conducted in Quebec.

A total of 3,966 adolescents volunteered to participate annually in an online survey in which they reported their cannabis use in the past year (on a 6-point scale ranging from "never" to "every day") and any psychosis symptoms they experienced as per the Adolescent Psychotic-Like Symptoms Screener.

With the survey data, a statistical model was created showing the relationship between marijuana use and psychosis symptoms over ages 13-16 (χ²=48.22). Once the model incorporated time-lagged associations between earlier cannabis use and psychosis symptom onset 12 months later, the model acquired a better fit (χ²=26.07, P=0.001), according to Patricia Conrod, PhD, of the University of Montreal, CHU Sainte-Justine Research Center, and colleagues, reporting online in a research letter in .

"This analysis demonstrates a predominant association at the individual level of cannabis use frequency with increased psychosis symptoms, and not the opposite, in the general population at a developmental stage when both phenomena have their onset.

"[T]hese results emphasize the need for targeted cannabis use prevention as jurisdictions revise their cannabis regulatory policies," the researchers suggested. nationwide, possibly as soon as this week.

"Promoting evidence-based interventions and policies that reduce access to and demand for cannabis among youth could lead to population-based reductions in risk for major psychiatric conditions," Conrod and colleagues wrote.

The investigators used data from teenagers in the Co-Venture cohort, representing 76% of all grade 7 students at 31 secondary schools in the Montreal area. Data from 3,720 were included in the analysis. The researchers acknowledged that the study's reliance on unverified, self-reported cannabis use and psychosis symptoms were an important limitation.

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