Even More Evidence Links Marijuana to Psychosis
For those who think marijuana is harmless, researchers are suggesting people take another look. John McGrath of Queensland Brain Institute in Australia has just confirmed what many studies have concluded, that marijuana isn’t as harmless as some think.
"Compared with those who had never used cannabis, young adults who had six or more years since first use of cannabis were twice as likely to develop a non-affective psychosis (such as schizophrenia)," McGrath wrote in a study published in the Archives of General Psychiatry journal.
There have been a variety of studies as of late that have suggested smoking cannabis can double the risk of psychosis, but the British study was the first to look specifically at skunk. Skunk has higher amounts of the psychoactive ingredient THC which can produce psychotic symptoms such as hallucinations, delusions and paranoia.
The researchers included 3,801 young adults who were born in Brisbane from 1981 to 1984. At the 21-year follow up, the participants, whose average age was about 20, were asked about marijuana use. The researchers also measured whether those in the study had psychotic symptoms.
Of the 1,272 participants who had never used marijuana, 26 or 2 percent were diagnosed with psychosis. Of the 322 people who had used marijuana for six or more years, 12 or 3.7 percent were diagnosed with the illness. Overall, 65 people were diagnosed with psychosis, according to the study. McGrath said that even those who used marijuana for fewer than three years still had an increased risk of scoring higher than those who had not.
The study also looked at siblings who both smoked pot and found that those who smoked it longer had a higher score for psychotic-like delusions than the other sibling who smoked for a shorter time.
About 2.4 million American adults have schizophrenia, according to the National Institutes of Health. The disorder often appears in men in their late teens and early 20s, while in women it generally strikes in their early 20s or 30s. It is associated with delusions, hallucinations and disordered thinking, McGrath said. It is unclear what causes the disease.
McGrath said, "the nature of the relationship between psychosis and cannabis use is by no means simple and more research is needed to examine the mechanisms at work.” What is a known fact is this is just another study confirming that long term use of marijuana can be linked to forms of psychosis.