How does marijuana affect mental illness?
Psychotic episodes, like schizophrenia and bipolar disorder, are thought to occur because of problems in the dopamine neurotransmitter systems in the brain. Some drugs that are used to treat psychosis (such as neuroleptics) work by lowering dopamine levels in the brain. Drugs like the THC in marijuana (a cannabinoid) have the opposite effect, increasing the amount of dopamine released in the body, which may lead to psychosis (Hall, 1998; Stahl, 1996). In problems like obsessive-compulsive disorder, marijuana stimulates activity in the brain, especially parts that regulate starting/stopping behaviour, loss of control and compulsion (Solowij, 1999; Volkow et al., 1996). This effect is quite unique because other drugs (cocaine, heroin, amphetamines, alcohol and benzodiazepines) reduce activity in these regions, making control more difficult (Solowij, 1999). Recent research also suggests that marijuana helps bipolar patients manage their treatment (Grinspoon & Bakalar, 1998). Some people u
