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Psychoactive Drugs Tobacco, Alcohol, and Illicit Substances

1. What are psychoactive drugs and how much are they used?

  • 1.1 How many people smoke tobacco?
  • 1.2 What are the trends in alcohol consumption?
  • 1.3 How many people use illicit drugs?

The source document for this Digest states:

This report describes the current understanding of the neuroscience of psychoactive substance use and dependence.1 Neuroscience is concerned with all of the functions of the nervous system, particularly the brain. Psychoactive substances have the ability to change consciousness, mood, and thoughts. This report draws on the explosive growth in knowledge in neuroscience in recent decades, which has transformed our understanding of the actions of psychoactive substances, and contributed new insights into why many people use psychoactive substances, and why some use them to the extent of causing themselves harm or of becoming dependent.

1 [The term "substance use" is employed in this document to refer to any form of self-administration of a psychoactive substance. It is used instead of the term "substance abuse" as a broader term encompassing all levels of substance involvement, including occasional and prolonged consumption of a substance.]

The need for this report comes from these advances in neuroscience research, which have shown that substance dependence is a chronic, relapsing disorder with a biological and genetic basis, and is not simply due to lack of will or desire to quit. Effective treatments and interventions for substance dependence do exist, and involve both pharmacological and behavioural interventions. The stigma associated with substance use and dependence can prevent individuals from seeking treatment, and can prevent adequate policies regarding prevention and treatment to be implemented. A WHO study of attitudes to 18 disabilities in 14 countries found that ‘‘substance addiction’’ ranked at or near the top in terms of social disapproval or stigma, and that ‘‘alcoholism’’ ranked not far behind in most of the societies studied (1). Neuroscience-based knowledge of substance dependence affords an opportunity to clarify misunderstandings, and to eliminate incorrect and damaging stereotypes.

This report covers information on the global burden of substance use and dependence, including global statistics, individual and societal consequences of the acute and chronic use of psychoactive substances, and illustrates the pervasive effects of substance dependence throughout the world. The effects of psychoactive substances on the brain, and how they promote the development of dependence is discussed, along with the genetic and environmental factors that may predispose or protect individuals from developing substance dependence. Many treatments, both biological and psychological, are available and are discussed, along with the ethical implications of such treatments. This report concludes with key recommendations and implications of neuroscientific knowledge of substance dependence for public health policy.

Global use of psychoactive substances and burden to health

Tobacco use

Global use of alcohol, tobacco, and other controlled substances is growing rapidly, and contributing significantly to the global burden of disease.

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Global use of psychoactive substances and burden to health, p.7-8

1.1 How many people smoke tobacco?

The source document for this Digest states:

Table 1 shows the prevalence of smoking among adults and youths in selected countries. Smoking is spreading rapidly in developing countries and among women. Currently, 50% of men and 9% of women in developing countries smoke, as compared with 35% of men and 22% of women in developed countries. China, in particular, contributes significantly to the epidemic in developing countries. Indeed, the per capita consumption of cigarettes in Asia and the Far East is higher than in other parts of the world, with the Americas and Eastern Europe following closely behind (2).

Table 1. Prevalence of smoking among adults and youths in selected countries

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Global use of psychoactive substances and burden to health, Tobacco use, p.8

1.2 What are the trends in alcohol consumption?

The source document for this Digest states:

Alcohol and tobacco are similar in several ways: both are legal substances, both are widely available in most parts of the world, and both are marketed aggressively by transnational corporations that target young people in advertising and promotion campaigns. According to the Global status report on alcohol (3) and as shown in Fig. 1 below, the level of consumption of alcohol has declined in the past twenty years in developed countries, but is increasing in developing countries, especially in the Western Pacific Region, where the annual per capita consumption among adults ranges from 5 to 9 litres of pure alcohol, and also in countries of the former Soviet Union (3). To a great extent the rise in the rate of alcohol consumption in developing countries is driven by rates in Asian countries. The level of consumption of alcohol is much lower in the African, Eastern Mediterranean, and South-East Asian regions

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Global use of psychoactive substances and burden to health, Alcohol use, p.8-9

1.3 How many people use illicit drugs?

The source document for this Digest states:

Data from the United Nations Office on Drugs and Crime (UNODC) show large-scale seizures of cocaine, heroin, cannabis and amphetamine-type stimulants in different parts of the world. Availability of cocaine, heroin and cannabis depends on the level of cultivation in source countries and on the success or failure of trafficking organizations. However, even with increased levels of law enforcement activities, there always seems to be enough available to users.

According to UNODC estimates (5), about 200 million people make illicit use of one type of illicit substance or another. Table 2 shows that cannabis is the most common illicit substance used, followed by amphetamines, cocaine and the opioids. Illicit substance use is a predominantly male activity, much more so than cigarette smoking and alcohol consumption. Substance use is also more prevalent among young people than in older age groups. The data in Table 2 show that 2.7% of the total global population and 3.9% of people 15 years and above had used cannabis at least once between 2000 and 2001. In many developed countries, for example Canada, the USA and European countries, more than 2% of youths reported heroin use and almost 5% reported smoking cocaine in their lifetime. Indeed, 8% of youths in western Europe and more than 20% of those in the USA have reported using at least one type of illicit substance other than cannabis. There is evidence of rapid increases in the use of amphetamine-type stimulants among teenagers in Asia and Europe. Injecting substance use is also a growing phenomenon, with implications for the spread of HIV infection in an increasing number of countries (Box 1).

Table 2. Annual prevalence estimates of global illicit substance use, 2000-2001

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Global use of psychoactive substances and burden to health, p.9-10


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