Cannabis effects on white matter microstructure and outcomes in early phase psychosis: a 1 year dual site longitudinal study.

Schizophrenia, affecting 1% of the population, causes significant burden to individuals, families and society. Fortunately, specialized early phase psychosis (EPP) intervention programs result in positive long term outcomes. Unfortunately, the high rate of cannabis use in EPP affects these outcomes. Cannabis use results in a higher risk of relapse and severity of symptoms, reductions in individuals following thru with treatment and overall functioning deficits (e.g. work and school) compared to EPP non-cannabis users. Cannabis use can reduce the recovery gains of these young adults. Cannabis, thru its receptors located on the brains white matter (WM) tracts, may be affecting WM development during the critical brain developmental period of young adulthood, resulting in these negative outcomes. Damage to the connections in the brain have themselves been reported in long-term schizophrenia, potentially causing schizophrenia symptoms. The effects of regular cannabis use, on a potentially already damaged brain in early disease, has not been well studied but we suspect that it too reduces the strength of brain connections but in a different way than schizophrenia. Our 2 site study (Halifax, NS; London, Ont), will recruit subjects to four groups: cannabis use disorder (CUD) and non-CUD patients within the first year of entry to the EPP programs, and CUD and non-CUD age and sex matched healthy controls. We will collect detailed information about past and current use of cannabis and clinical measures using established rating scales and methods. We will combine novel brain imaging techniques focusing on WM to generate an understanding of specific WM abnormalities associated with cannabis use in EPP, separate from illness and cannabis effects alone. This research design will allow a pioneer assessment of the potential negative impact of regular cannabis use longitudinally in this population (baseline and 1 year later), allowing for more directed education and treatments.