There is growing interest in the relationship between cannabis and psychosis.
The link between cannabis use and psychosis comprises three distinct relationships: acute
psychosis associated with cannabis intoxication, acute psychosis that lasts beyond the period
of acute intoxication, and persistent psychosis not time-locked to exposure. Experimental
studies reveal that cannabis, tetrahydrocannabinol (THC) and synthetic cannabinoids reliably
produce transient positive, negative, and cognitive symptoms in healthy volunteers.
Case-studies indicate that cannabinoids can induce acute psychosis which lasts beyond the
period of acute intoxication and persisting as long as a month. Exposure to cannabis in adolescence
is associated with an increased risk for later psychotic disorder in adulthood; this
association is consistent, somewhat specific, shows a dose-response, and is biologically
plausible. The link between cannabinoids and psychosis is greater with earlier age of exposure
to cannabinoids, childhood abuse and genetic vulnerability. However, cannabinoids are
neither necessary nor sufficient to cause a persistent psychotic disorder. More likely cannabinoids are a ‘component
cause’ interacting with other known (family history) and unknown factors to result in psychosis outcomes.
While more research is needed to better understand the relationship between cannabinoid use and psychosis, and
the neural underpinnings of this link, clinicians should be mindful of the potential risk of psychosis especially in
vulnerable populations, including adolescents and those with a psychosis diathesis.