Marijuana affects the brainA number of studies have shown an association between chronic marijuana use and increased rates of anxiety, depression, suicidal ideation, and schizophrenia. Some of these studies have shown age at first use to be a factor, where early use is a marker of vulnerability to later problems. However, at this time, it not clear whether marijuana use causes mental problems, exacerbates them, or is used in attempt to self-medicate symptoms already in existence. Chronic marijuana use, especially in a very young person, may also be a marker of risk for mental illnesses, including addiction, stemming from genetic or environmental vulnerabilities, such as early exposure to stress or violence. At the present time, the strongest evidence links marijuana use and schizophrenia and/or related disorders6. High doses of marijuana can produce an acute psychotic reaction, and research suggests that in vulnerable individuals, marijuana use may be a factor that increases risk for the disease.
More information about Marijuana effects can be found at http://www.nida.nih.gov/infofacts/marijuana.html