Sunday, February 24, 2008
Marijuana Fact and Fiction
Why cannabis research is a good idea.
There is little doubt among responsible researchers that marijuana--although it is addictive for some people--is sometimes a clinically useful drug. However, there is little incentive for commercial pharmaceutical houses to pursue research on the cannabis plant itself, since they cannot patent it.
The use of marijuana in the treatment of glaucoma is well established. As for the relief of nausea caused by chemotherapy, the precise “antiemetic” mechanism has not yet been identified, but several studies show that marijuana works at least as well as the popular remedy Compazine for controlling nausea. Cancer patients have used marijuana successfully to increase appetite and combat severe weight loss.
Yet another intriguing possibility centers on Huntington’s chorea, the single-gene disease researchers spent years chasing down. Early data from the National Institutes of Health (NIH), reported in Science News, showed a loss of THC receptors in the brains of Huntington’s sufferers.
Queen Elizabeth believed that marijuana tamed her menstrual cramps back in the 16th Century, but there is no clinical and little anecdotal evidence to support this notion. Perhaps the anti-anxiety and mood elevating effects associated with marijuana are useful for menstrual irritation and mood swings, just as they are sometimes perceived to be useful by those suffering from depression.
The typical joint rolled in paper contains roughly 0.5 grams of plant matter, of which anywhere from 1 to 15 per cent is THC. THC content varies widely because some genetic strains of cannabis are more potent than others. This fact has led to intense debate in the United Kingdom over the issue of so-called “Skunk” marijuana. Skunk is not a new, lethally potent form of pot, but rather a shorthand term for describing one of several strains of strong, aromatic female marijuana plants. Most of the potent forms of marijuana for sale are hybrids resulting from cross-pollination of various strains. Of itself, “Skunk” marijuana is no more or less dangerous than other potent and popular varietals, such as “White Widow” or "Hawaiian Haze."
The half-life of marijuana is fairly short—about 50 hours for inexperienced users, and about half that for experienced users. However, THC and its metabolites are fat soluble, and are therefore easily stored in fatty tissue. Other drugs clear the system much more efficiently. The marijuana high may be history, but the metabolites live on--for up to 30 days. Blood tests can confirm THC in the body, but cannot reliably determine how recently the marijuana was smoked. There is no marijuana analysis kit comparable to the Breathalyzer test for alcohol. Drivers under the influence of cannabis may suffer some perceptual impairment. They tend to drive more slowly and take fewer risks, compared to drivers under the influence of alcohol. Possibly, cannabis smokers are hyperaware of the modest motor impairments they exhibit under the influence. Heavy drinkers are often unaware that there is anything wrong with their driving at all, as their sometimes-vociferous arguments with police officers and state troopers can attest.
As with cigarettes, chronic pot smoking can lead to chronic bronchitis. We don’t know for certain whether heavy marijuana use causes lung cancer, but it seems safe to assume that smoking vegetable matter in any form is not compatible with the long-term health of lung tissue. Patients with risk factors for cardiovascular disease are well advised not to smoke anything. Marijuana smoking can raise the resting heart rate as much as 30 per cent in a matter of minutes, and while there is no present evidence of harmful effects from this, we will have to monitor the situation more closely as pot-smoking and former pot-smoking Baby Boomers enter their cardiovascular disease years.
Other patients for whom marijuana is definitely not indicated include those suffering from respiratory disorders--asthma, emphysema, or bronchitis. In addition, schizophrenics or anyone at genetic risk for schizophrenia should shun pot, as it has been known to exacerbate or precipitate schizophrenic episodes—though it does not, as is commonly rumored, cause schizophrenia.
The evidence for significant impairment of cognitive function is equivocal—heavy marijuana use does not, like alcohol, result in gross structural brain damage. Numerous studies have addressed the possibility of subtler impairments in memory, attention, and the retention of new information. The extent to which such alterations are transient as opposed to long term is still under scientific debate.
Cannabis augments the effects of morphine in animal studies, thus allowing for a lower dose of opiates. Pain relief may be a primary attribute of anandamide—the brain’s own THC. Rats given the drug were less sensitive to pain than their non-drugged counterparts, as detailed in the Proceedings of the National Academy of Sciences. Drug companies may have closed the book on marijuana spin-offs too early. It would not be surprising if pills to selectively increase the amount of anandamide in the brain will one day augment or offer an alternative to existing anti-anxiety medications or pain relievers. On the other hand, a substance that blocks anandamide might find use as an agent to help combat memory loss.
For more, see: The Chemical Carousel: What Science Tells Us About Beating Addiction © Dirk Hanson 2008, 2009.
Related Posts: Anandamide: The Brain's Own Marijuana