Canadian Guidelines on Cannabis Use Disorder Among Older Adults.

BACKGROUND: Cannabis Use Disorder (CUD) is an emerging and diverse challenge among older adults. METHODS: The Canadian Coalition for Seniors' Mental Health, with financial support from Health Canada, has produced evidence-based guidelines on the prevention, identification, assessment, and treatment of this form of substance use disorder. CONCLUSIONS: Older adults may develop CUD in the setting of recreational and even medical use. Clinicians should remain vigilant for the detection of CUD, and they should be aware of strategies for prevention and managing its emergence and consequences The full version of these guidelines can be accessed at www.ccsmh.ca.

Broad Thinking: An Interview With Harold Kalant.

In this interview, Harold Kalant, M.D., Ph.D., professor emeritus at the University of Toronto, talks about his career in addiction science; his professional associations with E. M. Jellinek, Griffith Edwards, and other luminaries; the growth of the addiction field; and the issue of cannabis legalization in Canada, among other topics.

Intravenous self-administration of alcohol in rats-problems with translation to humans.

Alcohol is consumed orally by humans, and oral self-administration has been successfully modeled in laboratory animals. Over the last several years, attempts have been made to develop a procedure for the reliable intravenous (IV) self-administration of alcohol in rodents. IV self-administration would provide a better tool for investigating neurobiological mechanisms of alcohol reinforcement and dependence because confounding factors associated with oral self-administration, such as variations in orosensory sensitivity to alcohol and/or its absorption, are avoided. A review of the literature shows that rats, mice and non-human primates can initiate and maintain IV self-administration of alcohol. However, there are 50- to 100-fold interspecies differences in the reported alcohol infusion doses required. Most surprising is that the infusion dose (1-2 mg/kg) that reliably maintains IV alcohol self-administration in rats results in total alcohol intakes of only 20-25 mg/kg/hour, which are unlikely to have significant pharmacological effects. The evidence to support IV self-administration of such low doses of alcohol in rats as well as the potential biological mechanisms underlying such self-administration are discussed. The minute amounts of alcohol shown to reliably maintain IV self-administration behavior in rats challenge the relationship between their blood alcohol levels and the rewarding and reinforcing effects of alcohol.

A critique of cannabis legalization proposals in Canada.

An editorial in this issue describes a cannabis policy framework document issued by a major Canadian research centre, calling for legalization of non-medical use under strict controls to prevent increase in use, especially by adolescents and young adults who are most vulnerable to adverse effects of cannabis. It claims that such a system would eliminate the severe personal, social and monetary costs of prohibition, diminish the illicit market, and provide more humane management of cannabis use disorders. It claims that experience with regulation of alcohol and tobacco will enable a system based on public health principles to control access of youth to cannabis without the harm caused by prohibition. The present critique argues that the claims made against decriminalization and for legalization are unsupported, or even contradicted, by solid evidence. Early experience in other jurisdictions suggests that legalization increases use by adolescents and its attendant harms. Regulation of alcohol use does not provide a good model for cannabis controls because there is widespread alcohol use and harm among adolescents and young adults. Government monopolies of alcohol sale have been used primarily as sources of revenue rather than for guarding public health, and no reason has been offered to believe they would act differently with respect to cannabis. Good policy decisions require extensive unbiased information about the individual and social benefits and costs of both drug use and proposed control measures, and value judgments about the benefit/harm balance of each option. Important parts of the necessary knowledge about cannabis are not yet available, so that the value judgments are not yet possible. Therefore, a better case can be made for eliminating some of the harms of prohibition by decriminalization of cannabis possession and deferring decision about legalization until the necessary knowledge has been acquired.

Drug classification: science, politics, both or neither?

Governments currently classify illicit drugs for various purposes: to guide courts in the sentencing of convicted violators of drug control laws, to prioritize targets of prevention measures and to educate the public about relative risks of the various drugs. It has been proposed that classification should be conducted by scientists and drug experts rather than by politicians, so that it will reflect only accurate factual knowledge of drug effects and risks rather than political biases. Although this is an appealing goal, it is inherently impossible because rank-ordering of the drugs inevitably requires value judgements concerning the different types of harm. Such judgements, even by scientists, depend upon subjective personal criteria and not only upon scientific facts. Moreover, classification that is meant to guide the legal system in controlling dangerous drug use can function only if it is in harmony with the values and sentiments of the public. In some respects, politicians may be better attuned to public attitudes and wishes, and to what policies the public will support, than are scientific experts. The problems inherent in such drug classification are illustrated by the examples of cannabis and of salvinorin A. They raise the question as to whether the classification process really serves any socially beneficial purpose.

What neurobiology cannot tell us about addiction.

Molecular neurobiological studies have yielded enormous amounts of valuable information about neuronal response mechanisms and their adaptive changes. However, in relation to addiction this information is of limited value because almost every cell function appears to be involved. Thus it tells us only that neurons adapt to 'addictive drugs' as they do to all sorts of other functional disturbances. This information may be of limited help in the development of potential auxiliary agents for treatment of addiction. However, a reductionist approach which attempts to analyse addiction at ever finer levels of structure and function, is inherently incapable of explaining what causes these mechanisms to be brought into play in some cases and not in others, or by self-administration of a drug but not by passive exposure. There is abundant evidence that psychological, social, economic and specific situational factors play important roles in initiating addiction, in addition to genetic and other biological factors. Therefore, if we hope to be able to make predictions at any but a statistical level, or to develop effective means of prevention, it is necessary to devise appropriate integrative approaches to the study of addiction, rather than pursue an ever-finer reductive approach which leads steadily farther away from the complex interaction of drug, user, environment and specific situations that characterizes the problem in humans.

Adverse effects of cannabis on health: an update of the literature since 1996.

Recent research has clarified a number of important questions concerning adverse effects of cannabis on health. A causal role of acute cannabis intoxication in motor vehicle and other accidents has now been shown by the presence of measurable levels of Delta(9)-tetrahydrocannabinol (THC) in the blood of injured drivers in the absence of alcohol or other drugs, by surveys of driving under the influence of cannabis, and by significantly higher accident culpability risk of drivers using cannabis. Chronic inflammatory and precancerous changes in the airways have been demonstrated in cannabis smokers, and the most recent case-control study shows an increased risk of airways cancer that is proportional to the amount of cannabis use. Several different studies indicate that the epidemiological link between cannabis use and schizophrenia probably represents a causal role of cannabis in precipitating the onset or relapse of schizophrenia. A weaker but significant link between cannabis and depression has been found in various cohort studies, but the nature of the link is not yet clear. A large body of evidence now demonstrates that cannabis dependence, both behavioral and physical, does occur in about 7-10% of regular users, and that early onset of use, and especially of weekly or daily use, is a strong predictor of future dependence. Cognitive impairments of various types are readily demonstrable during acute cannabis intoxication, but there is no suitable evidence yet available to permit a decision as to whether long-lasting or permanent functional losses can result from chronic heavy use in adults. However, a small but growing body of evidence indicates subtle but apparently permanent effects on memory, information processing, and executive functions, in the offspring of women who used cannabis during pregnancy. In total, the evidence indicates that regular heavy use of cannabis carries significant risks for the individual user and for the health care system.