Going from being an occasional marijuana user to indulging every day increases the risk of psychosis by up to 159 percent, research revealed in July 2017.
Marijuana is thought to cause psychosis-like experiences by increasing a user’s risk of depression, a study found. The two mental health conditions have previously been linked.
Frequently abusing the substance also significantly reduces a user’s ability to resist socially unacceptable behavior when provoked, the research adds.
Study author Josiane Bourque from the University of Montreal, said: ‘Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms.
‘[Psychosis symptoms] may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there’s an increased risk of a first psychotic episode or another psychiatric condition.’
The researchers, from the University of Montreal, analyzed around 4,000 13-year-olds from 31 high schools in the surrounding area.
Every year for four years, the study’s participants completed questionnaires about any substance abuse and psychotic experiences.
Psychotic symptoms included perceptual aberration – for example feeling that something external is part of their body – and thinking they have been unjustly badly treated.
The participants also completed cognitive tasks that allowed the researchers to assess their IQ, memory and stimuli response.