Among all the participants, a longer duration since the first time they used cannabis was associated with multiple psychosis-related outcomes. “Compared with those who had never used cannabis, young adults who had six or more years since first use of cannabis (i.e., who commenced use when around 15 years or younger) were twice as likely to develop a non-affective psychosis and were four times as likely to have high scores on the Peters et al Delusions Inventory [a measure of delusion],” the authors write. “There was a ‘dose-response’ relationship between the variables of interest: the longer the duration since first cannabis use, the higher the risk of psychosis-related outcomes.”
“The nature of the relationship between psychosis and cannabis use is by no means simple,” they write. Individuals who had experienced hallucinations early in life were more likely to have used cannabis longer and to use it more frequently. “This demonstrates the complexity of the relationship: those individuals who were vulnerable to psychosis (i.e., those who had isolated psychotic symptoms) were more likely to commence cannabis use, which could then subsequently contribute to an increased risk of conversion to a non-affective psychotic disorder.”
Science Daily: Long-Time Cannabis Use Associated With Psychosis
March 2, 2010 at 2:29 pm
These articles of the link between cannabis and psychosis are popping up everywhere lately. Another attempt at reefer-madness as a last grasp by the “war-on-drugs” to re-frighten some of the majority of Americans who know cannabis is safe. The actual science behind these studies (or possibly it’s just one study that news organizations have written many net articles on) is most likely the fact that psychedelics (cannabis being a mild psychedelic)can bring existing psychosis to a head quicker, though these psychosis would develop anyway, usually before the age of thirty.
March 2, 2010 at 3:25 pm
I looked up the Peterson Delusion Index questionnaire, which can be read in the appendix to this PDF:
It sounds dramatic to say that someone is “delusional,” but the questions are things like, “Do you feel particularly close to God,” or, “Do you ever think that others can hear your thoughts?” Given how common these “delusional” beliefs are in the general, non-smoking, populace, I’m not very concerned if pot-smokers are more affected by them.
March 2, 2010 at 4:51 pm
Dustin – put down the pipe, read the study in question, and then comment if you have something relevant to say.
Joshua – Thanks for this. I read the questions at the end, but not the introductory material – do you know if they weigh certain questions more than others? (If it were me, I’d probably weigh the question about reading other people’s thoughts more heavily than the question about whether you feel particularly close to God” for example).
March 3, 2010 at 6:24 am
Headline should be “Pot smokers who started young more likely to exhibit psychic ability.” 🙂
March 4, 2010 at 8:28 pm
so booze is a magical wonder, but cannabis makes schizos? yeah.. right..
March 31, 2010 at 6:30 pm
April 1, 2010 at 7:29 pm
The use of these negative terms without example of the specific symptoms of “psychosis” leaves much to be desired. The one example they used was the generic term ‘hallucination’ but didn’t explain what kind of hallucination or how severe it was.
IMO this is just modern-day reefer madness. Not that I think pot is inherently harmless… because I don’t. But this article seems to be catered for the biased.
April 1, 2010 at 7:48 pm
guyfromcanada, Talmadge – you might want to try re-reading the article when you’re not stoned.
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