Schizophrenia

The abuse of street drugs such as LSD (acid), PCP (angel dust), or marijuana can produce symptoms that are similar to those of schizophrenia. When people take LSD or PCP, they often experience visual or auditory hallucinations. Marijuana use can cause delusions, especially the belief that people are watching the user and want to harm him or her. Unlike symptoms of schizophrenia, however, symptoms caused by street drugs almost always disappear within seventy-two hours after substance use has stopped.

Some people develop schizophrenia (and other mental disorders) around the same time that they begin using street drugs. For example, in the movie The Wall, it is not clear whether the main character's psychosis is caused by drug use, mental problems, or both.

For this reason, many relatives and friends of patients suffering from schizophrenia wonder whether the disorder was caused by drug abuse. Although street drugs can damage the brain and often produce symptoms that look like those of schizophrenia, it is very unlikely that the abuse of these drugs can actually cause schizophrenia in a person who is not already in the process of developing it.

A more likely explanation for the fact that some people develop schizophrenia around the same time they start using street drugs is that both of these things tend to happen at around the same age (teens to early twenties). Another explanation for the link between street-drug use and schizophrenia onset may be that people who are in the process of developing schizophrenia sometimes turn to mind-altering drugs to explain the frightening experiences they are having. Hearing voices for the first time in your life, for example, is a very frightening experience. If you then begin using marijuana or PCP, it provides you with a possible reason for hearing voices. You might reason that the voices are the result of the drugs rather than of a mental disorder that you cannot control.

Although there is currently no evidence that street-drug abuse causes schizophrenia, there is some evidence that it can make symptoms of schizophrenia worse. Also, schizophrenia researchers are still trying to find out if street-drug abuse can trigger schizophrenia in a person who is at risk for it. Risk factors for schizophrenia are discussed in chapter four.