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Psychoactive Drugs Tobacco, Alcohol, and Illicit Substances

2. How do psychoactive drugs affect health?

  • 2.1 What is the health burden attributable to psychoactive drugs?
  • 2.2 What main harmful effects are caused by psychoactive drug use?

2.1 What is the health burden attributable to psychoactive drugs?

The source document for this Digest states:

There is now a developing tradition of estimating the contribution of alcohol, tobacco and illicit substance use to the global burden of disease (GBD). The first significant attempt at this was in the WHO project on the Global burden of disease and injury (6). Based on a standard of measurement known as disability-adjusted life years (DALYs), estimates of the burden imposed on society due to premature death and years lived with disability were assessed. The global burden of disease project showed that tobacco and alcohol were major causes of mortality and disability in developed countries, with the impact of tobacco expected to increase in other parts of the world

Table 3 offers ample evidence that the burden of ill-health from use of psychoactive substances, taken together, is substantial: 8.9% in terms of DALYs. However, GBD findings re-emphasize that the main global health burden is due to licit rather than illicit substances.

Among the ten leading risk factors in terms of avoidable disease burden, tobacco was fourth and alcohol fifth for 2000, and remains high on the list in the 2010 and 2020 projections. Tobacco and alcohol contributed 4.1% and 4.0%, respectively, to the burden of ill health in 2000, while illicit substances contributed 0.8%. The burdens attributable to tobacco and alcohol are particularly acute among males in the developed countries (mainly Europe and North America). This is because men in developed countries have a long history of significant involvement with tobacco and alcohol and because people in these countries live long enough for substance- related health problems to develop.

Table 3. Percentage of total global mortality and DALYs attributable to tobacco, alcohol and illicit substances

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Global use of psychoactive substances and burden to health, Burden of disease, p.10-12

2.2 What main harmful effects are caused by psychoactive drug use?

The source document for this Digest states:

Mostly, people use psychoactive substances because they expect to benefit from their use, whether by pleasure or by the avoidance of pain, including social uses. But using psychoactive substances also carries with it the potential for harm, whether in the short run or in the longer term.

The main harmful effects due to substance use can be divided into four categories (see Fig. 2). First there are the chronic health effects. For alcohol this includes liver cirrhosis and a host of other chronic illnesses; for tobacco taken in cigarette form, this includes lung cancer, emphysema and other chronic illnesses. Through the sharing of needles, heroin use by injection is a main vector for transmission of infectious agents such as HIV (see Box 1) and hepatitis B and C virus in many countries. Second there are the acute or short-term biological health effects of the substance. Notably, for drugs such as opioids and alcohol, these include overdose.

Also classed in this category are the casualties due to the substance’s effects on physical coordination, concentration and judgement, in circumstances where these qualities are demanded. Casualties resulting from driving after drinking alcohol or after other drug use feature prominently in this category, but other accidents, suicide and (at least for alcohol) assaults are also included. The third and fourth categories of harmful effects comprise the adverse social consequences of the substance use: acute social problems, such as a sudden break in a relationship or an arrest, and chronic social problems, such as defaults in working life or in family roles

Source & ©: WHO  Neuroscience of psychoactive substance use and dependence, Summary (2004),
Adverse consequences of psychoactive substances and their mechanisms of action, p.12

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