Institute of Psychiatry Interview - Sir Prof. Robin Murray
Prof. Murray explains about the clear link between psychosis and cannabis use. The risk increases 2-3x for cannabis users. Effects are strongest with heavy cannabis smokers (4-5 high potency joints a day) and those starting before 15. The latter is probably due to a developing brain. The risk also depends on e.g. genetic vulnerability – not all users develop psychosis. Stopping cannabis is beneficial for recovery. Long time users will need more time to recover. New types of cannabis (e.g. skunk or synthetic) are more dangerous, as they contain higher THC levels.
Suggested further reading “The impact of cannabis use on age of onset and clinical characteristics in first-episode psychotic patients. Data from the Psychosis Incident Cohort Outcome Study (PICOS)”, Journal of Psychiatric Research, Volume 47, Issue 4, April 2013, Pages 438-444.