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IACM-Bulletin of August 30, 2009


Science — Cannabis use has other effects on lung function than tobacco use

According to a long-term epidemiological study conducted in New Zealand smoking of cannabis has other effects on the lungs than tobacco smoking. Researchers compared the associations between use of these substances and lung function in a group of 1037 adults at the age of 32. Their cannabis and tobacco use were requested at ages 18, 21, 26, and 32 years. The scientists summarized that "cannabis use was associated with higher lung volumes suggesting ... increased large-airways resistance, but there was little evidence for airflow obstruction or impairment of gas transfer."

In detail, cannabis use was "associated with higher forced vital capacity [maximum volume of air that a person can exhale after maximum inhalation], total lung capacity [volume of air contained in the lung at the end of maximal inspiration], functional residual capacity [volume of air present in the lungs at the end of passive expiration], and residual volume [amount of air left in the lungs after a maximal exhalation]." Cannabis was also associated with higher airways resistance but not with forced expiratory volume in 1 second [volume that can be exhaled within one second after maximum inhalation]. Authors noted that "these findings were similar amongst those who did not smoke tobacco." By contrast, tobacco use was associated with lower forced expiratory volume in 1 second.

(Source: Hancox RJ, Poulton R, Ely M, Welch D, Taylor DR, McLachlan CR, Greene JM, Moffitt TE, Caspi A, Sears MR. Effects of cannabis on lung function: a population-based cohort study. Eur Respir J. 2009 Aug 13. [Electronic publication ahead of print])

Science — Cannabis use may protect the brain from some consequences of alcohol use

Californian researchers investigated the effects of alcohol and cannabis use on the integrity of the white matter of the brain. They compared 42 adolescents aged 16 to 19 years who belonged to one of three groups: heavy alcohol drinkers, heavy alcohol drinkers who also were heavy cannabis users, and adolescents who did not use drugs (controls).

There were differences in eight white matter regions between alcohol drinkers and controls. However, in four of these regions, alcohol drinkers who also used cannabis presented with better results than alcohol drinkers. Authors noted that "binge drinkers who also use marijuana did not show as consistent a divergence from non-users as did the binge drink-only group." They said that it is "possible that marijuana may have some neuroprotective properties in mitigating alcohol-related oxidative stress" or induction of toxic cell death.

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(Source: Jacobus J, McQueeny T, Bava S, Schweinsburg BC, Frank LR, Yang TT, Tapert SF. White matter integrity in adolescents with histories of marijuana use and binge drinking. Neurotoxicol Teratol. 2009 Jul 23. [Electronic publication ahead of print])

Mexico decriminalized the possession of small amounts of cannabis, cocaine and heroin on 21 August - a move that prosecutors say makes sense even in the midst of the government's grueling battle against drug traffickers. Prosecutors said the new law sets clear limits that keep Mexico's police from going after casual users and offers them more time to concentrate on drug trafficking.

"This is not legalization, this is regulating the issue and giving citizens greater legal certainty," said Bernardo Espino del Castillo of the attorney general's office. The new law sets out maximum "personal use" amounts for drugs, also including LSD and methamphetamine. People detained with those quantities no longer face criminal prosecution. The maximum amount of cannabis for "personal use" under the new law is 5 grams.

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(Sources: UPI of 22 August 2009, Associated Press of 21 August 2009)

Argentina — Supreme Court against prison sentence for possession of cannabis

The Supreme Court ruled out prison for cannabis possession on 25 August, saying the government should go after major traffickers and provide treatment instead of jail for consumers of cannabis. Ruling in a case involving several young men caught with cannabis cigarettes in their pockets, the judges struck down a law providing for up to two years in prison for possession of small amounts of narcotics.

This decision does not legalize drug possession outright. But Argentina's Cabinet chief favours keeping drug addicts out of the justice system, and was waiting for the ruling before forwarding a proposed law to Congress. The seven judges said they were unanimous in "declaring the unconstitutionality of prison for private consumption." "Each individual adult is responsible for making decisions freely about their desired lifestyle without state interference," their ruling said. "Private conduct is allowed unless it constitutes a real danger or causes damage to property or the rights of others."

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(Source: Associated press of 25 August 2009)

News in brief

Science — Multiple sclerosis

According to research at the University of Nottingham, UK, patients with multiple sclerosis have increased levels of endocannabinoids in their blood compared to healthy people. Scientists noted that the endocannabinoid system is altered in multiple sclerosis, and that it "may be dynamically modulated depending on the subtype of the disease." (Source: Jean-Gilles L, et al. J Neurol Sci 2009 Aug 19. [Electronic publication ahead of print]).

Science — Tolerance to morphine

According to animal research at Harvard Medical School, USA, a combination of a cannabinoid and a NMDA receptor antagonist can prevent the development of tolerance of morphine, when the opiate is given chronically. (Source: Fischer BD, et al. Neuropharmacology 2009 Aug 20. [Electronic publication ahead of print]).

Science — Inflammation of the intestine

According to an animal model of colitis the natural cannabinoid cannabidiol (CBD) may be beneficial in the treatment of chronic inflammation of the intestine. Scientists of the University of Naples, Italy, administered a chemical to mice which induced a colitis, which was reduced by CBD. They summarized that CBD "prevents experimental colitis in mice." (Source: Borrelli F, et al. J Mol Med 2009 Aug 20. [Electronic publication ahead of print]).

Science — Detection of THC

Research results already published in the New Scientist on 9 August 2009 were now published in the British Journal of Pharmacology. According to Australian researchers stress and fasting by regular cannabis users may result in an increased THC concentration in the blood by mobilization of THC from fat, where it was accumulated. This may result in a positive drug test even after long abstinence to cannabis. Scientists noted that "further research will need to confirm whether this can lead to functional effects, such as impaired cognitive function or 'flashbacks'." (Source: Gunasekaran N, et al. Br J Pharmacol 2009 Aug 14. [Electronic publication ahead of print])

Science — Anorexia nervosa

Scientists of the University of Naples, Italy, found out that certain variations in the gene for the CB1 receptor and the gene for the enzyme FAAH, which is responsible for the degradation of endocannabinoids, are more often found in patients suffering from anorexia nervosa and/or bulimia nervosa. (Source: Monteleone P, et al. Genes Brain Behav 2009 Jun 26. [Electronic publication ahead of print])