Cannabis use linked to earlier onset of psychosis

Cannabis use is associated with an earlier onset of psychosis, particularly for users in their 30s, according to a new study from Australia [1, 2].

The findings challenge the common belief that cannabis primarily impacts the adolescent brain. By demonstrating that the drug can accelerate the onset of psychotic symptoms in older adults, the research suggests a broader window of vulnerability than previously understood [1, 3].

Researchers at the University of New South Wales (UNSW Sydney), led by senior author Professor Matthew Large, examined how cannabis use influences the age at which psychosis first appears [1, 2]. The study found that across all ages, cannabis users develop psychosis on average 2.5 years earlier than non-users ^[2].

The effect is more pronounced in older demographics. Cannabis users who develop psychosis in their 30s experience symptoms more than six years earlier than non-users ^[1]. For individuals already susceptible to psychosis, cannabis use in their 30s was associated with an onset 6.3 years earlier ^[3].

This data indicates that the risk of early-onset psychosis persists well into adulthood. While much of the existing medical literature focuses on the developing brains of teenagers, these results highlight a significant correlation for adults in their third decade of life [1, 3].

The UNSW Sydney team aimed to clarify the relationship between substance use and the timing of psychiatric symptoms [1, 3]. The research suggests that the timing of the first psychotic episode can be shifted significantly by the use of cannabis, regardless of whether the user is a teenager or an adult [2, 3].