Marijuana and Mental Illness
The Archives of General Psychiatry published a landmark study in 2010 that found early marijuana use is “associated with psychosis-related outcomes in young adults.” When teenagers had used marijuana by the age of 15, researchers in Australia concluded that a statistically significant percentage of them developed psychosis by early adulthood. Since the researchers only looked at paired siblings, they reduced or eliminated the effects of genetic and environmental factors that may have skewed previous studies, an effect known as “residual confounding.”
The researchers from Queensland stated bluntly: “the longer the duration since first cannabis [marijuana] use, the higher the risk of psychosis-related outcomes.” The study, entitled “Association Between Cannabis Use and Psychosis-Related Outcomes Using Sibling Pair Analysis in a Cohort of Young Adults,” measured non-affective psychosis, hallucinations, and Peters et al Delusion Inventory (PDI) scores. The mental illness study found that “compared with those who had never used cannabis, young adults who had six or more years since first use of cannabis were twice as likely to develop a non-affective psychosis and were four times as likely to have high scores on the PDI.”
In short, any use of marijuana in early teenage years increases the probability of an individual developing psychosis. The American Psychological Association defines psychosis as “an abnormal mental state characterized by serious impairments or disruptions in the most fundamental higher brain functions--perception, cognition and cognitive processing, and emotions or affect--as manifested in behavioral phenomena, such as delusions, hallucinations, and significantly disorganized speech.”
The National Survey on Drug Abuse and Health, conducted by the University of Michigan as part of its Monitoring the Future (MTF) program, recently reported that 33.4 percent of 10th graders in the United States had used marijuana at one point during their life in 2010, up from 29.9 percent in 2008. This means that, on average, in a typical secondary school class of 23 students, seven of those students would have already used marijuana. If the results of the Australian study hold true for the American students, those seven students--compared to the other 16 classmates who had never smoked marijuana--would be four times more likely to score high on the Peters Delusion Inventory.
If the risk of mental illness is greater than previously believed, so is the acceptance of casual marijuana usage, especially for “medical” purposes. In February 2009, the same month that Congress passed the $787 billion stimulus program (American Recovery and Reinvestment Act), U.S. Attorney General Eric Holder, citing “limited resources,” stated that the U.S. Justice Department (D.O.J.) would no longer raid medical marijuana clinics. He reversed the drug enforcement policies of previous attorney generals.
More recently, the M.T.F. survey, funded by the National Institute for Drug Abuse, an arm of the National Institutes of Health, reported the marijuana use among 8th graders had increased from 14.3 percent in 2008 to 15.7 percent in 2009 and 17.3 percent in 2010 (see figure). The M.T.F. Drug Abuse survey also reported that--for the first time in 30 years--less than half (46.8 percent) of high school seniors in 2010 saw “great risk” in using marijuana regularly.
In California, the “medical marijuana” law allows dispensaries to sell marijuana with a doctor’s prescription. Although originally marketed to the public as a means to alleviate suffering, such as vomiting, that is often associated with chemotherapy or the treatment of AIDs, prescriptions are now commonly written for a variety of other illnesses, including migraines. Despite the fact that some states allow “medical marijuana” dispensaries, the U.S. Drug Enforcement Administration (D.E.A.) still classifies cannabis as a Schedule I Drug. Under authority of the Controlled Substances Act, this means that marijuana: 1) has a high potential for abuse; 2) no current accepted medical use in treatment; and, 3) has lack of accepted safety.
When Proposition 19, which would legalize possession of marijuana in small quantities, appeared headed for passage in California in November 2010, Attorney General Holder stated the D.O.J. would “vigorously enforce” federal marijuana laws. Proposition 19 failed by a slim margin.
The murder of U.S. District Judge John M. Roll by Jared Lee Loughner in Tucson, Arizona, on January 8, 2011 has a strong marijuana angle. Reportedly an early and relatively heavy user of marijuana, Jared Loughner, as a minor, was arrested for possession of drug paraphernalia in 2007, but received a small fine of $20. After his latest arrest, authorities found candles near a white plastic skull resting on dried orange peels in a terra cotta pot in his back yard. Loughner also used salvia divinorum, a plant of the mint family with hallucinogenic properties. Although currently legal in many states, the D.E.A. is reviewing whether to classify salvia divinorum, like marijuana, a Schedule I Drug, its strictest classification.
The aforementioned Queensland study, funded by the National Health and Medical Research Council of Australia and led by Dr. John McGrath, only looked at psychosis-related outcomes for young adults. Researchers could not “confidently exclude the possibility that some of the cohort members may have developed psychosis as young adolescents, which may have contributed to subsequent cannabis use.” Consequently, this mental illness study on the effects of early cannabis use may not provide insight into the relationship between an individual’s early marijuana use and any change in behavior during late teens.
A slew of defense and prosecution psychiatrists will evaluate Loughner’s mental condition and produce expert reports on his mental state before, during, and after the shooting in Tucson. The American Psychiatric Association lists a whole section related to cannabis use, including schizophrenia, but judges and juries will determine Jared Loughner’s exact culpability in the murders of six individuals, as well as the attempted assassination of Congresswoman Gabrielle Giffords and the wounding of a dozen others.
The association between marijuana and mental illness, long dismissed as either non-existent or irrelevant, can be traced, in part, to the popularity of a movie entitled “Reefer Madness.” A church group originally produced the low-budget, black and white film in 1936, entitling it “Tell Your Children.” During the late 1930s, the Bureau of Narcotics (a predecessor of the D.E.A.) under the Roosevelt Administration distributed it under several names, including “Reefer Madness.” When a founder of the National Organization for the Reform of Marijuana Laws located the film in the 1970s in the Library of Congress, he distributed it widely. The movie became a counter culture phenomenon: the association of smoking a joint and instant insanity was perceived as both a hoax and a fraud. Following the release of the Australian study and the shooting in Tucson, the question must be asked: could “Reefer Madness” hold a smidgeon of truth?
References:
www.nida.nih.gov/nidahome.html
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