Article by Angela Stelmakowich, Growth Op
Age of first use of cannabis may influence future consumption, whether that be higher or lower, but changes in consumption between age 19 and 22 appear not to be associated with a greater frequency of psychotic-like experiences (PLEs).
That was the finding of a new study, published in Schizophrenia Research, by a team of researchers from around the world.
Although no causal relationship has been proved, the association between changes in cannabis use and changes in the frequency of PLEs “strongly suggests a bidirectional association and a reduction of PLEs after the cessation of cannabis use,” authors write in the study. So researchers sought to investigate the association of changes in cannabis use over a period of three years with the occurrence of PLEs in a non-clinical sample of young adults.
Study participants were initially recruited at age 14 in Europe and follow-ups were done at age 16, 19 and 22. Of the 552 subjects who cited use at age 19, “549 reported having experienced at least one psychotic experience of any form at age 19,” the study notes.
Of the 552 participants, 37.9 per cent reduced their cannabis use between age 19 and age 22, there was no change in use for 33.5 per cent and 28.4 per cent increased use over the course of three years.
“More participants reported no use of cannabis within the past year at age 22 (31.5 per cent) than at age 19 (23 per cent),” study authors write.
Mean cannabis use, however, rose between ages 19 and 22, with the age of first use “positively associated with a change in cannabis use between the two time points.” Still, cannabis use “was not significantly associated with psychotic-like experiences at age 19 or 22.”
One 22-year-old participant explained his experience as follows: “I think that definitely a motivation for stopping was every time I got reasonably high, I would start to have paranoid thoughts, [although] not in a psychotic way… Taking a break has stopped that, so I think that was a good decision.”
Researchers did observe a positive association between perceived stress and psychotic experiences at age 22. This “emphasizes the importance of stress experiences in developing psychosis independent of cannabis use,” they note.