Marijuana (cannabis) is the most popular illegal drug in the world. It is estimated that worldwide, over 160,000,000 people use marijuana every day.
Marijuana use can lead to psychosis.
Psychosis is a major mental disorder, impairing a person's ability to think, respond emotionally, remember, communicate, interpret reality and behave appropriately -- to a degree that the person can't meet the ordinary demands of life. Symptoms can include seeing, hearing, smelling, or tasting things that are not there; paranoia; and delusional thoughts. Depending on the condition, psychotic symptoms may be constant or might come and go.
Some of the drugs known to cause psychosis include marijuana, LSD (lysergic acid diethylamide), PCP (phencyclidine), crystal meth (methamphetamine), and ketamine.
Researchers recently reviewed the world's literature on marijuana and psychosis. This was a meta-analysis of 83 studies on the relationship between marijuana use and the onset of psychosis. They found that the age of onset of psychosis for people who used marijuana was 2.7 years younger than for nonusers who developed psychosis.
The authors concluded that “Cannabis use plays a causal role in the development of psychosis in some patients. The results suggest the need for renewed warnings about the potentially harmful effects of cannabis.”