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NEUROSCIENCE OF PSYCHOACTIVE SUBSTANCE USE AND DEPENDENCE

and distilled spirits. Because the use of caffeinated substances is relatively
unproblematic, it is not further considered in this report. While inhalants are
also widely available, they are mostly used for psychoactive purposes by those
below the age of easy access to alcohol, tobacco and other psychoactive
substances.
While there is a clear rationale for a separate legal status for medications,
the rationale for the distinction between substances that are under
international control and those that are not is more problematic. The
substances which are included in the international conventions reflect
historical understandings in particular cultural settings about what should
be viewed as uniquely dangerous or alien. Some psychopharmacologists or
epidemiologists today, for instance, would argue that alcohol is inherently
no less dangerous or harmful than the drugs included in the international
conventions. Moreover, as discussed below, dependence on nicotine in
tobacco is associated with more death and ill-health than dependence on
other psychoactive substances. As will be seen in the chapters which follow,
the growing knowledge of the neuroscience of psychoactive substance use
has emphasized the commonalities in action which span the three sociolegal
statuses into which the substances are divided.

Global use of psychoactive substances
Tobacco
Many types of tobacco products are consumed throughout the world but the
most popular form of nicotine use is cigarette smoking. Smoking is a
ubiquitous activity: more than 5500 billion cigarettes are manufactured
annually and there are 1.2 billion smokers in the world. This number is
expected to increase to 2 billion by 2030 (Mackay & Eriksen, 2002; World Bank,
1999). 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 (Mackay & Eriksen,
2002).
A conceptual framework for describing the different stages of cigarette
smoking epidemics in different regions of the world has been proposed by
Lopez, Collishaw & Piha (1994). In this model, there are four stages of the
epidemic on a continuum ranging from low prevalence of smoking to a stage
in which about one-third of deaths among men in a particular country are
attributable to smoking. In Stage 1, less than 20% of the men and a
considerably lower percentage of women smoke. Available epidemiological
data show that many countries in sub-Saharan Africa fall into this category

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