More threads by David Baxter PhD

David Baxter PhD

Late Founder
Marijuana Abuse Contributes to Schizophrenia, Psychosis
Wednesday, February 21, 2007

Some believe marijuana to be relatively harmless, especially when compared to other illicit substances. But, according to a new study published in the journal of Current Psychiatry, mental health experts know better. Collected evidence adds weight to the idea that, in addition to its obviously detrimental physical side-effects, marijuana abuse/dependence may intensify the symptoms of psychosis in patients with mental illness and increase the chances that healthy subjects will eventually develop the same conditions. This theory first arose more than four decades ago when use of the drug was first becoming acceptable to mainstream America, but many clinicians assumed at the time that psychotic patients were simply more likely to use marijuana as a self-medicating sedative.

Today, the common caricature of marijuana users growing increasingly paranoid about imagined or exaggerated threats is supported by clinical research. As a result of cannabis-induced psychosis or pre-existing schizophrenia complicated by smoking pot, users may experience the type of episodes more often associated with higher-level hallucinogens. Examples include periods of severe psychological discomfort, anti-social behavior and withdrawal, and an increasing tendency to "lash out" at perceived enemies who may include innocent bystanders or family members.

Much like alcohol, the adverse effects of marijuana and its potential for abuse correspond closely to the age at which subjects first come into contact with the substance. The human brain is still forming throughout adolescence, and regular exposure to such intoxicants can actually alter the development of the body's neural pathways, leading to familiarity with, tolerance for, or addiction to the drug(s) in question. Teenagers are particularly susceptible to developing harmful and potentially long-lasting habits whose influence extends beyond physical addiction:

One 15-year study of 50,000 young people in Sweden, for example, found those who had tried marijuana by the time they were 18 were 2.4 times more likely to receive a diagnosis of schizophrenia.​

While some criticized this study as imprecise and overstated, newer, more specific research again indicates that adolescent pot smokers are more likely to develop schizophreniform disorders, particularly if their first usage occurs before the age of fifteen. Additional longitudinal studies display a clear association between marijuana and psychosis even after adjusting the data for pre-existing conditions, additional drug use and related factors. The chances of any teenager developing schizophrenia after puffing on a single joint are obviously remote, but all relevant research names regular, long-term abuse as a contributing factor, and young people with predispositions toward psychosis are particuarly vulnerable. Marijuana is in no way a harmless substance, and because the vast majority of teenagers will eventually come into contact with it in some form, they should be made aware of its psychotic implications:

Although marijuana use is not a "necessary" causal factor in psychotic illness, most users do not develop the disorder, and many persons with schizophrenia do not use marijuana, strong evidence indicates that it is one of many factors that can cause a psychotic illness.​

And this should be reason enough for teens to stay away.
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