Christchurch, New Zealand: According to longitudinal data published in the New Zealand Medical Journal.
A team of New Zealand researchers assessed the relationship between marijuana use and the severity of psychotic symptoms in a cohort of over 1,200 subjects born in 1977. Investigators compared the symptom profile of cannabis users and non -consumers at 18, 21 and age 25.
Researchers reported that cannabis-using subjects were more likely than non-users to report experiencing a greater variety of psychotic symptoms overall. However, the investigators acknowledged that consumers were not more likely to report having severe symptoms.
The authors reported: “The present analyzes aimed to determine if there was a qualitative difference in the type of symptoms reported by the two groups. …Both groups tended to report low-intensity common symptoms (such as “having ideas or beliefs that others do not share”), and neither group was likely to report what would be considered more severe positive symptoms of psychosis.
They concluded: “Collectively, the results suggest that while those who were regular cannabis users reported significantly more symptoms than non-users, the symptom profile between the two groups did not differ, showing that there was no evidence of greater severity. ‘ among regular cannabis users.
Although the use of cannabis and other controlled substances is more common in people with psychotic illnesses, studies indicate that lifetime incidences of marijuana-induced psychosis are relatively rare in those without already received a prior diagnosis of psychiatric illness.
The full text of the study, “Cannabis use and patterns of psychotic symptomology in a longitudinal birth cohort,” appears in the New Zealand Medical Journal.