Drug Watch International

MARIJUANA RESEARCH REVIEW

Study cites marijuana as factor in increased crime and emergency room episodes

"A substantial proportion of the US population has used illicit drugs, resulting in increased risk of injury disease, and death," (BA Rouse, Clinical Chemistry 42:8(B) 1330-1336,1996). From this perspective, Rouse examined the National Institute of Justice Drug Use Forecasting (DUF) system and two studies from the Substance Abuse and Mental Health Services Administration, i.e., the National Household Survey on Drug Abuse and the Drug Abuse Warning Network (DAWN), to chart the role of illegal or nonmedical drug use in emergency room episodes and interactions with the criminal justice system.

The DAWN report showed marijuana use had increased significantly in all age groups and that in emergency room treatment "most marijuana-related episodes also included mentions of other drugs, particularly alcohol and cocaine." Nonetheless, marijuana use alone was a significant factor in emergency room visits.

Commentary: In the DUF study on the relationship between drugs and crime it was noted that since an arrest may occur long after an offense has taken place determination as to whether or not drugs were a factor is often minimized. Additionally, only the most serious offense for which a person was booked was reflected. That being the case, it is highly likely that drug offenses are under reported. ##

Marijuana users incur increased health care costs

Marijuana smoke contains carcinogens and more tars than tobacco smoke. However, little epidimeologic evidence has identified marijuana smoking as a risk factor for health. Polen et al. (Western Journal of Medicine, Vol.158, pp 596-601,1993) studied the health effects of smoking marijuana by comparing daily marijuana smokers who never smoked tobacco (452 patients) with a demographically similar group of non-smokers of either substance (450 patients). Daily marijuana smokers had a 19% increased risk of out patient visits for respiratory illnesses, a 32% increased risk of injury, and a 9% increased risk of other illnesses compared to non-smokers. They also had a 50% increased risk of being admitted to the hospital. These results were adjusted for sex, age, race, education, marital status, and alcohol consumption.

Commentary: Daily marijuana smoking, even in the absences of tobacco, appears to be associated with an elevated risk of adverse health outcomes, including an excessive use of health care resources. Many marijuana smokers also smoke tobacco and the adverse health consequences of using these two substances together are likely to be multiplied. ##

Lung cancer causing carcinogen more prevalent in marijuana than tobacco

A breakthrough report published in the journal Science, October 18,1996, provides the first true molecular evidence conclusively linking components in tobacco smoking to lung cancer. A chemical found in tobacco smoking, benzopyrene, causes genetic damage in lung cells that is identical to the damage observed in the DNA of most malignant tumors of the lungs.

Although scientists have been convinced in the past that smoking causes lung cancer, the strong statistical associations did not provide absolute proof. This paper absolutely pinpoints that mutations in lung cancer cells are caused by benzopyrene. An average marijuana cigarette contains 30 nanograms of this carcinogen compared to 21 nanograms in an average tobacco cigarette (Marijuana and Health, National Academy of Sciences, Institute of Medicine report, 1982). This potent carcinogen suppresses a gene that controls growth of cells. When this gene is damaged the body becomes more susceptible to cancer. This gene, P53, is related to half of all human cancers and as many as 70% of lung cancers.

Commentary: Clearly marijuana smoke contains more of the potent carcinogen benzopyrene than tobacco smoke. Furthermore, the technique of smoking marijuana by inhaling deeply and holding the smoke within the lungs presents a chance of much greater exposure than a conventional tobacco cigarette. ##

Marijuana interferes with brain's ability to metabolize glucose

Marijuana is the most widely used illicit drug in the United States, but its short and long term effects on brain metabolism are not clearly understood. Volkow et al (Psychiatry Research: Neuroimaging, Vol. 67, pp 29-38,1996) studied brain glucose metabolism in daily marijuana users at baseline and during marijuana intoxication. They used the sophisticated technique of positron emission tomography (PET scan) which gives a visual picture of the actively metabolizing brain.

The results of eight chronic marijuana users were compared with age and sex matched normal subjects. They found that THC, the main psychoactive component of marijuana, produced lower glucose metabolism in the cerebellar part of the brain. A single THC dose in a chronic user increases metabolism in other specific parts of the brain. This does not occur in the non-using controls. The activation of chemical metabolism pathways in the brains of users, as compared to the controls, could lead to the drive and compulsion to self-administer the drug observed in addicted individuals.

Commentary: This sophisticated use of PET scanning which illustrates individual regions of the brain and their abilities to metabolize glucose, the main energy source of the brain, documents an abnormality in chronic users of marijuana. The location of the abnormality in the cerebellum could account for the motor defects and lack of coordination previously reported in these subjects. This has obvious implications for public safety and operation of motor vehicles by marijuana users. ##  

Researcher calls for more studies of impact of marijuana on brain

In an editorial (JAMA 996;275:521-527) Robert I. Block, Ph.D., discusses a study by Pope & Yurgelun-Todd in the same issue relative to marijuana use and brain function. Dr. Block laments that there is "so little scientific information to communicate about adverse effects of chronic marijuana use on human cognition or brain function." He cites the Pope & Yurgelun-Todd study, which "shows impairment in mental flexibility and abstraction, as well as some aspects of learning" in frequent marijuana users, and adds that "With continued use of marijuana...the impairments might increase over the years."

Block notes that there is evidence of cognitive deficits "persisting for prolonged periods following cessation of marijuana use, consistent with marijuana-induced brain alterations," and says that the recent increase in marijuana use by US youth is a "compelling motivation" to conduct more rigorous testing using the most modern detection techniques.

Commentary: The editorialist feels that far too few studies have been done on this aspect of marijuana use and praised the Pope and Yurgelun-Todd study for "incorporating a rigorously supervised, 19-hour abstinence period before testing." His suggestion that matched studies must be done to measure intellectual ability prior to the onset of drug use is seemingly impractical in that it would require being able to predetermine who would use illicit drugs. However, more well designed and controlled studies in this area would certainly be useful. ##

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Material used in this publication has been reviewed and commented on by William M. Bennett, M.D., Professor of Medicine, Division of Nephrology, Clinical Pharmacology and Hypertension at Oregon Health Sciences University, Portland, Oregon

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