Psychotic symptoms more likely with cannabis 16:58 01 December 04 NewScientist.com news service Using marijuana in adolescence and early adulthood can cause psychotic symptoms later in life, a new study suggests. The risk of developing these symptoms is “moderate”, say researchers, though is higher in people with a pre-disposition to psychosis. Up to a third of people develop signs of psychosis at some point during their lives and several studies have already linked cannabis use with psychotic symptoms. But it is often difficult to decipher whether cannabis really triggers psychotic symptoms - such as hearing voices and paranoia - or...