IACM-Bulletin of May 9, 2004

Science — Decriminalization does not increase cannabis use

Researchers of the University of California and the University of Amsterdam investigated the effect of criminal laws on cannabis use and concluded that "drug policies may have less impact on cannabis use than is currently thought." Their research was published in the May issue of the American Journal of Public Health.

Researchers compared groups of experienced cannabis users in similar cities with opposing cannabis policies - Amsterdam, the Netherlands (decriminalization), and San Francisco, USA (criminalization). Besides higher drug use in San Francisco researchers found strong similarities between users across both cities. There was "no evidence to support claims that criminalization reduces use or that decriminalization increases use."

"Despite widespread lawful availability of cannabis in Amsterdam, there were no differences between the two cities in age at onset of use, age at first regular use, or age at the start of maximum use. ... We also found consistent similarities in patterns of use across the different policy contexts," the study says.

(Source: Reinarman C, Cohen PD, Kaal HL. The limited relevance of drug policy: cannabis in Amsterdam and in San Francisco. Am J Public Health 2004;94(5):836-42)

Science — In persons with chronic hepatitis C, daily use of cannabis may promote development of liver fibrosis

French researchers investigated the impact of cannabis use on the development of fibrosis in chronic hepatitis C in 195 patients. In a multivariate analysis a high progression rate to fibrosis was independently related to daily cannabis use, alcohol intake of more than 30 gram per day, age at contamination above 25 years, and physical activity. However, moderate us of cannabis had no effect on the development of fibrosis.

Their research was presented at a conference in Berlin, Germany, in April. 51 per cent of the participants were nonusers of cannabis, 17 per cent were occasional users (mean: 7 cannabis cigarettes per month) and 32 per cent were daily users (mean: 107 cigarettes per month).

The effect of cannabis varied among subgroups. If persons were younger than 40 years and alcohol intake was below 30 grams/day 20 per cent of non and occasional users, but 37 per cent of daily users had fibrosis. If persons were older than 40 years and alcohol intake was below 30 grams/day 35 per cent of non and occasional users, but 71 per cent of daily users had fibrosis. If persons were younger than 40 years and alcohol intake was above 30 grams/day 38 per cent of non and occasional users, but 50 per cent of daily users had fibrosis. If persons were older than 40 years and alcohol intake was above 30 grams/day 76 per cent of non and occasional users, but 50 per cent of daily users had fibrosis. The distribution in the last subgroup is somewhat surprising.

In animal research the group had shown that development of liver fibrosis may be regulated by cannabinoid receptors, and that in cirrhotic patients CB1 receptors are markedly increased in certain liver cells. Following chronic tetrachloride intoxication mice without CB1 receptors react with a decreased development of liver fibrosis compared to normal mice.

It is recommended that people with chronic hepatitis C avoid daily use of cannabis, while occasional use seems to be safe. This first study needs replication in a larger group of patients before it is possible to make final recommendations.

(Sources: Hezode C, et al. Daily cannabis smoking as a risk factor for fibrosis progression in chronic hepatitis C. Abstract 68. 39th Annual European Association for the Study of the Liver Conference, 14-18 April 2004. Berlin, Germany; Grenard P, et al. Reduced liver fibrosis in CB1 receptor knockout mice. Abstract. J Hepatology 2004; 40(S1): 8.)

News in brief

UK — GW Pharmaceuticals

GW Pharmaceuticals has warned that regulatory concerns will delay the launch of their medicinal cannabis extract for a second time. The authorities have demanded more information on how the drug is formulated and on safety and effectiveness in multiple sclerosis and pain caused by nerve damage. The Medicines and Healthcare Products Regulatory Authority has had a dossier of scientific information on the cannabis extract including the results of several human trials, for more than a year but has repeatedly expressed dissatisfaction with the data. (Source: Independent of 1 May 2004)

USA — Prevalence of cannabis use

Among the adult US population, the percentage of cannabis users remained stable at about 4.0 per cent between 1991 and 2002. Marijuana abuse or dependence slightly increased from 1.2 per cent to 1.5 per cent. It remained stable among young white men and women, but increased among young black men and women and young Hispanic men. (Source: Compton WM, et al. JAMA 2004;291(17):2114-21)

Science — Multiple sclerosis

In a mouse model of multiple sclerosis (experimental autoimmune encephalomyelitis, EAE) a synthetic cannabinoid attenuated the interaction of white blood cells with endothelium in the brain that causes inflammation. This cannabinoid effect was blocked by antagonists to the CB1 and to the CB2 receptor. (Source: Ni X, et al. Mult Scler 2004;10(2):158-64.)

Science — Sleep

Eight volunteers received four treatments before sleep (at 10 p.m.): placebo, 15 mg THC, 5 mg THC combined with 5 mg cannabidiol (CBD), and 15 mg THC combined with 15 mg CBD. Fifteen milligrams THC would appear to increase sleepiness, while 15 mg CBD appears to have alerting properties. (Source: Nicholson AN et al., J Clin Psychopharmacol 2004;24(3):305-313.)

Science — Driving

Researchers estimated the association between drug use and motor vehicle accidents by conducting a prospective case-control study from May 2000 to August 2001. The 110 cases were drivers involved in road crashes, who needed to stay in hospital. The 816 controls were drivers recruited at random while driving on public roads. The risk for trauma from road accidents was increased by 5-fold with use of benzodiazepines. The risk for alcohol was increased by 5.5 with a blood alcohol concentrations (BAC) between 0.05-0.08 per cent and by 15.5 with a BAC above 0.08 per cent. Increased risks were assessed for drivers using amphetamines, cocaine, or opiates. No increased risk was found for drivers who had used cannabis. (Source: Movig KL, et al. Accid Anal Prev 2004;36(4):631-6.)

Holland — Discussion on legal status

The government intends to prohibit the legal sale of cannabis that is grown in the Netherlands in coffee shops. Ministers intend to initiate an investigation whether the dangers of the drug have increased due to its increased THC concentration. Dutch cities oppose the plan and some call for legalisation not only of sale but also of cultivation of the plant. Cities fear that criminalization increases the problem due to increased illegal sale on the streets. (Sources: VNG of 26 April 2004, Utrechts Nieuwsblatt of 16 April 2004)