Does Cannabis Abuse Represent a Gateway to Harder Drugs?

The question of whether cannabis represents a gateway to harder drugs has occupied clinicians and researchers for 30 years. The reason for the interest in this question has been that a transition to harder drugs – heroin, amphetamines or cocaine – represents a significant increase in the degree of risk to which the individual is exposed. Even though cannabis is more psychotoxic than heroin, intravenous heroin abuse is in many other respects a considerably more serious condition than cannabis dependence. With heroin – which is also much more expensive than cannabis –, addiction not infrequently develops quickly, the dependence is strong, and mortality is considerably higher, mainly owing to overdoses. It is the rule rather than the exception that heroin-dependent individuals become socially marginalised. The abuse of both amphetamines and cocaine (not least in the form of “crack”) also leads to rapid development of severe dependence, with the risk of a series of mental side-effects and high mortality levels. Moreover, transition to intravenous abuse adds the risk of HIV infection. The most extensive studies in this field have been carried out by Denise Kandel and her research team. They showed, at an early Read more […]

Cannabis and Pregnancy

THC is a substance which passes from the mother’s blood to that of the foetus. This means that THC can cause direct damage to the foetus during pregnancy. (THC is also passed on to the infant via breast-milk.) Animal experiments have shown a number of very serious effects on the gestation of, and on the young born to, females which have been given cannabis or THC during gestation. These findings have naturally given rise to questions concerning the risks to which the human foetus is exposed if the mother smokes hashish or marijuana during pregnancy (). Researchers are here confronted with the usual problems of finding a reliable design for their studies, including comparable control groups. Further, research of this type is faced with particular difficulties as regards finding means of excluding other factors that might explain damage that has been observed, such as other drugs (including alcohol and tobacco), inadequate nutrition and infections during pregnancy. Moreover, it is also difficult to find suitable methods of measurement with sufficient sensitivity to detect even damage of a subtle nature. The conceivable – and suspected – harmful effects of cannabis can be divided into the following categories: Effects Read more […]

Changing Patterns of Cocaine Use: Longitudinal Observations, Consequences, and Treatment

In 1858 the Austrian frigate Novara was sent to South America on a most unusual mission. The Novara was named after the city in which the Austrians had defeated the Italians, thereby stopping a threatening cultural and political renaissance. On board the Novara was a trade expert, Doctor Scherzer, who was intrigued by another Italian “renaissance” started by Milan neurolgist Paola Mantegazza. Mantegazza had published an 1857 paper proclaiming the medical importance of coca that he had chewed while a resident of Peru (Mantegazza 1857). The paper was the newest curiosity of the European medical community which even awarded Mantegazza a prize for this work in 1859 (Mortimer 1901). The Novara stopped in Peru and Scherzer took a quantity of coca leaves back to the great chemist Wohler at the University of Gottingen in Germany. Wohler’s assistant, Albert Nieman, named the isolated alkaloid “cocaine” in 1859/1860 (). The isolation and naming of the alkaloid signalled the start of 125 years of changing patterns of cocaine use. Prior to that time, only coca products were available, and the patterns of their use had not changed substantially in over 4700 years. For most of its early history, cocaine remained hidden Read more […]

Cocaine: Longitudinal study of users (1975-1983)

Methods A total of 118 cocaine users were recruited for study in 1974. Of these, 19 were selected for interview and questionnaire study while 99 (85 males, 14 females) were selected for a more comprehensive longitudinal study. All 99 users (18-38 years old) were social-recreational users who met the initial requirement of having used a minimum of 1 gram of cocaine per month for 12 months (range 1-4 grams). The majority of users were students (73 percent,) while others listed their occupations as housewives, business people, writers, attorneys, physicians, secretaries, teachers, or unemployed. Exaninations and tests were performed on each subject at 6-month intervals for 4 years (1975, 1976, 1977, 1978) and then at approximately 18-month intervals for another 5 years. Examination procedures included a personal history questionnaire, drug history questionnaire, subjective drug effects questionnaire, mental status exanination, the Minnesota Multiphasic Personality Inventory (MMPI), the Experiential World Inventory (EWI), in-depth interviews, and physical examinations (for most subjects). In addition, assays were performed on samples of cocaine used by these subjects. An important caveat is that a number of users dropped Read more […]

Human Dependence on Tobacco and Opioids: Common Factors

Recent years have seen increasing acceptance of the notion that tobacco is an addictive or dependence-producing substance, particularly as it is used in cigarette smoking. This idea is supported by the observations that tobacco serves as a reinforcer (i.e., it maintains behavior leading to its use) and that most people who smoke cigarettes would like to quit but cannot, even in the face of well documented health risks and economic sacrifices (Surgeon General’s Report 1979). The term “drug dependence” suggests that (1) the drug serves as a reinforcer, (2) behavior occurs which is maintained by the opportunity to take the drug, and/or (3) other reinforcers are sacrificed as a consequence of taking the drug (). Many cigarette smokers in some degree satisfy these criteria for drug dependence (). Since cigarette smoking has only recently been conceptualized as an instance of drug dependence, it should be useful to systematically compare cigarette smoking with another more thoroughly studied dependence process such as opioid dependence or narcotic addiction. At first blush, cigarette smoke and opioid drugs appear to produce vastly differing pharmacological and behavioral effects: large doses of opioids can produce Read more […]

Drug Preference in Humans: Lorazepam

A drug’s capacity to reinforce behavior in a laboratory setting usually correlates with its dependence potential in the general population. In laboratory tests, diazepam is not an effective positive reinforcer, either in laboratory animals using drug self-administration tests () or in normal human volunteer subjects using a choice test (). The failure to find evidence for a positive reinforcing effect of diazepam in these experimental tests is inconsistent with clinical reports that diazepam is used excessively by some people. The failure to demonstrate the positive reinforcing efficacy of diazepam in an experimental situation may be due in part to the drug’s long duration of action (half-life = 24 – 48 hours). In animal self-administration studies that test the reinforcing efficacy of drugs, it has been found that benzodiazepines that have shorter durations of action are also more effective reinforcers (). In the present study, human subjects were tested for preference for lorazepam, a benzodiazepine with effects similar to diazepam but with a shorter half-life than diazepam (half-life = 12-15 hours). Method Subjects. Twelve normal healthy volunteers, aged 21 to 27 (4 males, 8 females) participated in this study. Read more […]

Multiple Drug Use Epidemiology, Correlates, and Consequences

The initial focus is on the conceptual issues essential to the understanding of multiple drug use. This is followed by a discussion of the developmental nature of multiple drug use and the various strategies that have been designed to measure multiple use. The third section of the paper contains a review of the extent of multiple drug use in various segments of society with data from the Monitoring-the-Future surveys of high school seniors, the National Survey on Drug Abuse, and the Treatment Outcome Prospective Study of drug abuse treatment clients. The conclusion is that multiple drug use is pervasive. The next section deals with several consequences associated with multiple drug use: automobile accidents, delinquency, and emergency room visits. The final section outlines some of the prevention and treatment implications of multiple drug use from a public policy perspective. In a study of the effects of a single drug upon behavior, the implications are manifold. Dosage levels, modes of administration, baseline states, the expectations of the subjects and of the investigators, the environment in which the drug is taken — all these variables, and others as well, make human psychochemical studies difficult and complex. Read more […]

Policy Implications of Multiple Drug Use

Public policies that deal with the use and abuse of alcohol and drugs are very fragmented, reflecting in many ways the history of various substances as well as the role played by the substances in this society. Alcohol is a good example. Because the impact of alcohol on traffic fatalities is so painfully obvious, public interest in the control of alcohol has increased in the recent past. There have been a number of initiatives at Federal, state, and local levels concerning enforcement of minimum age drinking and dram shop liability laws and a push in some areas for raising the driving age. However, very little public policy attention has been directed toward the other control strategies that might have a larger impact on alcohol consumption and its relationship to traffic accidents and fatalities (i.e., changes in laws that would eliminate tax deductions for advertising, restriction of advertising of various types of alcoholic beverages, or substantial increases in the tax placed on alcoholic beverages and thus on the price). After all, when the economics of alcohol is examined it is easy to see how thoroughly interwoven alcohol is in society. The value of alcohol in the advertising, trucking, and agricultural sectors Read more […]

The Epidemiology of Multiple Drug Use

How much multiple drug use is there? What proportion of the population at any one point in time is using/abusing multiple substances? Has use of multiple substances become more normative in the recent past as opposed to exclusive use of a favorite drug? What are the principal consequences of multiple drug use? Do these consequences differ according to pharmacological parameters for interactive potential or are there other parameters of almost equal predictive value? To what extent are the consequences attributed to single drugs (traffic accidents labeled as alcohol related) really the result of impaired judgment and performance from ingestion of multiple substances? These are just a few of the questions that need to be addressed within the scientific and public policy communities. In the following section some epidemiological data pertinent to understanding the “extent” of multiple drug use are presented. Monitoring-the-Future Studies Each year since 1975, researchers at the Institute for Social Research at the University of Michigan have administered questionnaires to about 17,000 high school seniors attending schools randomly chosen to be representative of all high schools in the continental United States. These Read more […]

Measuring the Developmental Nature of Multiple Drug Use

There have been a number of studies in which attempts have been made to measure or assess multiple drug use. Some of these are from general populations while others are focused on specific subpopulations of users. The studies are grouped more on the basis of the approach taken to assessing multiple drug use than on the patterns uncovered. There are at least four different groupings of studies and some studies fit into more than one grouping. Developmental Patterns of Onset of Use One of the most influential attempts to describe patterns of multiple drug use is the “stages of drug use” model developed by Kandel. Kandel posited that persons proceed from licit to illicit drugs and from use of less to more serious drugs. The stages of drug use involvement that she identified were: (1) no use of any drugs; (2) use of beer or wine; (3) use of cigarettes and/or hard liquor; (4) use of marijuana; and (5) use of illicit drugs other than marijuana. Although it is not made explicit by Kandel, there is an implication that the drugs from the earlier stages of development are “carried forward” into the later stages of drug involvement. Thus, a marijuana user is likely to continue his or her use of cigarettes/hard liquor and beer Read more […]