Link Between Marijuana and Psychosis Goes Both Ways

An anonymous reader writes with news of a study out of the Netherlands (abstract) about the link between psychosis and marijuana use. The researchers wanted to examine what caused the relationship — was marijuana use leading to psychosis, or did those suffering from psychosis have a higher tendency to seek out marijuana? As it turns out, they found evidence for both. From the article: "... using pot at 16 years old was linked to psychotic symptoms three years later, and psychotic symptoms at age 16 were linked to pot use at age 19. This was true even when the researchers accounted for mental illness in the kids' families, alcohol use and tobacco use. Griffith-Lendering said she could not say how much more likely young pot users were to exhibit psychotic symptoms later on. Also, the new study cannot prove one causes the other. Genetics may also explain the link between pot use and psychosis, said Griffith-Lendering."

Comments

Re:So

[Baloroth]

You misinterpreted her statement. The correlation is, in fact, given in the abstract (relevant quote below). What she says she cannot do, because the study did not examine it, was how likely young pot users were to exhibit psychotic symptoms later, i.e. when they were not young (they only covered between 13 and 19 years old, looks like).

Findings
Significant associations (r=.12-.23) were observed between psychosis vulnerability and cannabis use at all assessments. Also, cannabis use at age 16 predicted psychosis vulnerability at age 19 (z=2.6, p<.05). Furthermore, psychosis vulnerability at ages 13 (z=2.0, p<.05) and 16 (z=3.0, p<.05) predicted cannabis use at, respectively, ages 16 and 19.