Many young people start taking drugs because they want to know what it feels like. Pressure from peer groups may also play a part, particularly with drugs such as alcohol and cannabis, which are to some degree socially acceptable. This in turn may be tied up with the wish to belong to a group who have a common interest in drug taking and there may be an element of rebellion against accepted values. This need to achieve social acceptance may well be symptomatic of an underlying character disorder so that there are both social and psychological factors at work.

It has long been suggested that people who become drug dependent differ in their genetic or biochemical make-up from those who show no interest in drugs. This has been particularly suggested in alcoholism, which might be regarded as a disease of metabolism, one facet of which is craving for alcohol. This is an attractive hypothesis because it takes the ‘sin’ out of dependence and puts it in a medical setting, but so far there is little evidence to support it.

There is little doubt that the availability and price of drugs of dependence influence both the amount and pattern of dependence. For example, countries where alcohol is cheap, such as France and South Africa, have a high incidence of alcoholism, cirrhosis of the liver, etc.

It has long been known that those who have to work long hours and do arduous jobs may turn to certain drugs to give them energy. In South America, for example, the natives who were pressed into service in the silver mines by the Spanish chewed coca leaves to give themselves energy. The use of cocaine among workers in high-pressure financial institutions and in the modern entertainment industry is well known. Doctors and nurses through the stresses and pressures of their vocation have a long history of being particularly susceptible to the temptations offered by the use of stimulant drugs, especially given the long hours they have to work and the accessibility of drugs. The emotional involvement that comes with working with the very ill has driven many a health worker to the use of opioids at one time or another. Nowadays, access to these drugs is very strictly controlled and their use is (or should be) documented meticulously. The records are inspected regularly and those who seek to remove these drugs from stock risk heavy penalties, not least de-registration and loss of their career.