U.S. studies show that people who use marijuana are significantly more likely to experience negative emotions, particularly feeling alienated from others. The studies reveal that they are more likely to feel that others wish them harm or are deceiving them. Brain scans reveal that the drug also increases signal connectivity in regions of the brain that have previously been linked to psychosis, which is associated with severe depression. Teenagers are particularly affected because their brains are still developing.
The study was done on 60 people in Bethesda, Maryland, half of whom are dependent on marijuana. Brain scans were also taken of all of the participants. Dr Cameron Carter, editor of the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, where the study was published, said: ‘These brain imaging data provide a link between changes in brain systems involved in reward and psychopathology and chronic cannabis abuse, suggesting a mechanism by which heavy use of this popular drug may lead to depression and other even more severe forms of mental illness.’
People who used cannabis at least twice to three times a week at 17 are more likely to experience hypomania (a mild form of mania, marked by elation and hyperactivity) in their early twenties. Research published over the summer discovered that going from an occasional use of marijuana to an everyday indulgence increases the risk of psychosis by up to 159 percent. Marijuana is thought to cause psychosis-like experiences by increasing a user’s risk of depression.
Study author Josiane Bourque from the University of Montreal said, ‘Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms. They may be infrequent and thus not problematic for the adolescent. When these experiences are reported continuously, year after year, then there’s an increased risk of a first psychotic episode or another psychiatric condition.’