New Pot Studies: Mostly Good News, But Don't Get Up Too Fast
Three marijuana studies were released in three separate countries during the week of March 13th: two hopeful, one cautionary. The first study seems to confirm a medicinal benefit of marijuana -- that it eases Multiple Sclerosis symptoms. The second study indicates that marijuana may be helpful in shrinking brain tumors. The third signals an area of possible caution, asserting that pot can be a health risk.Guess which study made headlines?The cautionary report, which claims to have documented an increased risk of heart attack within an hour of smoking, was front-page news across the country. The two other studies, one from the U.K. and one from Spain, received little attention from the U.S. media.All three studies were conducted at highly respected scientific institutions. The first study, written by a team of British scientists including Lora Layward of the MS Society of Britain and published in the journal Nature, that showed that compounds which mimic cannabis ameliorated MS symptoms in mice."This work gives support to anecdotal reports from people that say cannabis can alleviate spasticity and tremor," Layward told reporters. "This is the first time it has been shown objectively and scientifically that cannabis derivatives can control some of the symptoms of Multiple Sclerosis."The report pointed out that symptoms were eased in within sixty seconds of the drug's intake. Layward, bemoaning the current legal problems faced by many MS sufferers, added, "It is an unacceptable state of affairs when people suffering from a serious disease feel driven to break the law."In Spain, researchers at the Complutense and Autonoma Universities in Madrid found that inoperable brain tumors in rats were completely dissipated by the introduction of cannabis in one third of the test subjects, and that another third lived an average of 40 days longer than expected. The same type of tumors, which inflict thousands of humans, generally kill patients within a year, regardless of any treatment currently available. While the researchers were quick to point out that smoking cannabis should not preclude more traditional interventions, they also admit that they are not certain exactly how cannabis works on the tumors. Their best guess is that cannabis stimulates the immune system to attack the cancerous cells.The report that motivated concern -- and got the media's attention -- was presented by Harvard's Dr. Murray A. Middleman at the American Heart Association's annual conference on cardiovascular disease in San Diego. It showed that smoking marijuana temporarily raises the risk of heart attack in people already at risk of heart disease.Dr. Middleman noted marijuana's tendency to increase heart rates in reclining smokers. If those rates are rapidily changed -- for example, if the smoker stands up -- people with pre-existing coronary trouble may experience heart attacks. The study examined 3,882 heart attack sufferers, of which 124 were marijuana users. Of those users, 37 claimed to have used marijuana within 24 hours of their heart attack, and 9 had used it within the previous hour. The risk of heart attack, calculated the researchers, was 4.8 times higher than normal within an hour of smoking, but dropped to 1.7 times normal risk by the second hour.Because this report caused a fair amount of concern, the Week On Line (WOL), a publication of the Drug Reform Coordination Network, recently checked its validity with Dr. Lester Grinspoon, one of the world's foremost marijuana researchers and a colleague of Dr. Middleman's at Harvard. Dr. Grinspoon is and is author of several books, including the seminal "Marihuana Reconsidered."WOL: Dr. Grinspoon, what is your assessment of the Middleman report?Dr. Grinspoon: (Laughs). I've been getting phone calls all week about it. I even spoke with Dr. Middleman this week to ask him for his report. It has not yet been written. The only thing he does have is an abstract. Now, let me say that since 1967 there have been numerous reports and studies, each of which the American media has blown out of all proportion, stating one or another supposed ill effect of marijuana use. I can list them, if you'd like. 'Increase in the size of the ventricles, decrease in testosterone, destruction of chromosomes.' All were front-page stories, and none of them have ever been replicated. In other words, they didn't pan out scientifically. Of course, the studies that contradicted them ended up on page 31 or thereabouts, if they got mentioned at all.WOL: So you don't give much weight to Dr. Middleman's findings?Dr. Grinspoon: Well, I would point out that out of 3,882 patients, we're talking about 9 who used marijuana within an hour of the onset of a heart attack. That's around 0.2 percent. By sheer mathematics, given that people sleep eight hours per day or so, we can deduce that 6.7 percent of those patients emptied their bowels within an hour of onset. It's incredible to me that the numbers here could be said to constitute a significant risk factor.WOL: Dr. Middleman said in an interview that he believes that it is the increased heart rate from smoking marijuana that is responsible.Dr. Grinspoon: Yes, and he put that increase at 40 beats per minute. In truth, that number is closer to 20 beats per minute, which is probably consistent with running up the stairs in one's house.WOL: So you disagree with Dr. Middleman's characterization of the risk as 'significant'?Dr. Grinspoon: First, let me say that I blame the media far more than I do Dr. Middleman. I read his abstract, and in its conclusion he cautioned against making too much of the data. Conceivably, there is some risk, although if there is, it is barely measurable. Even assuming that the data presented is right, one must still wait to see if it can be replicated.WOL: You seem to be pretty skeptical about the chances of that happening.Dr. Grinspoon: Well, in 1997, Kaiser Permanente did a large-scale study* which included more than 65,000 admitted marijuana users, and they could not demonstrate any impact of marijuana use on mortality. If marijuana use really was a significant risk factor for heart attack, it is hard to believe that it didn't turn up there. Again, I'm not saying that there is absolutely no risk demonstrated here. But given the history of the research since 1967, I'd be surprised if these findings don't go down the same chute as all of the other front-page scare stories.*NOTE: In the April, 1997 edition of The American Journal of Public Health, Dr. Stephen Sidney wrote about a long-term (12-year) study undertaken by Kaiser Permanente into the mortality rates of marijuana smokers. The study population comprised 65,171 subjects aged 15 through 49 years. Conclusion: Marijuana use had little effect on non-AIDS mortality in men and on total mortality in women.