Cannabis "increases risk of psychosis"

"Teenagers and young adults who frequently use cannabis are increasing their risk of suffering from psychotic symptoms such as bizarre behaviour and delusions later in life, Dutch scientists say.

"Young people with a family history, or pre-existing susceptibility to mental instability, are particularly vulnerable to the negative effects of the drug.

"'Cannabis does not act in the same fashion on psychosis risk for everybody. There is a group that is particularly susceptible', Professor Jim van Os, of Maastricht University in the Netherlands, told a news conference on Wednesday.

"He and his colleagues studied 2,437 young people aged 14-24 and identified those with a predisposition for psychosis. They also questioned them about their cannabis use and followed them up for four years.

"'The results show that in the group without vulnerability to psychosis, there was a small effect of cannabis on the onset of psychotic symptoms four years later', Van Os said. 'But this risk was four times bigger in individuals who had a personal vulnerability to psychosis'." [My emphasis - N]

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