To understand how addiction works, it is important to recognise that addiction is not an ‘all-or-nothing’ phenomenon. In 1976, psychiatrists Griffith Edwards and Milton Gross published their ideas about alcohol dependence being a ‘clinical syndrome’ or collection of symptoms that can vary in levels of severity. Thanks to these insights, we now understand that addiction or drug dependence exists on a spectrum, and people can move backwards and forwards along this spectrum at different times in their life. This has transformed our understanding of alcoholism and addiction, and challenged previous ‘all-or-nothing’ concepts of addiction that described it as a disease or moral failing.
Addiction can be seen as one of many stages of drug use during a person’s life. A young adult might first experiment with drugs at a party or nightclub, partly because the opportunity presents itself. This can be followed by occasional or recreational drug use. Some people will begin to use drugs more frequently and may experience problems with addiction before they can reduce or stop their drug use.
Three dimensions shape the way people progress through these stages - the biological, psychological and social. Opportunities to use drugs come via people we know or meet, and are inherently social. The decision to accept or refuse drugs can also involve all three of these dimensions.
A teenager may be more likely (under certain circumstances) to accept drugs than a young adult because of genetic and developmental factors. Similarly, a young adult might be more likely to accept a drug offer compared to someone older. A majority of young adults will stop or reduce their drug taking as they mature and take on greater responsibilities. A smaller number will experience drug addiction.
The factors that influence people’s drug use experimentation can also influence the development of addiction. Research involving children of parents with drug use problems found that these children were more likely to have early opportunities to use cannabis and more quickly developed cannabis dependence. Similarly, our own research into ecstasy use has found that regular involvement in particular social settings (e.g. electronic dance music events) can contribute to people using ecstasy for the first time or using it more often.
On the other hand, some factors may be closely associated with specific stages of drug use. Trauma is a good example of this. A person’s experience of a traumatic life event is more likely to affect their development of drug dependence than their decision to try a drug for the first time.
In recent years, we have seen changes in the ‘age structure’ of addiction. Binge drinking and alcohol dependence has become common among middle-aged adults in some countries, with some concerning increases in women. The use and misuse of prescription drugs, including opioids for pain management, is also contributing to substance dependence in older adults. The emerging use of medical cannabis for management of chronic pain and other conditions might also have implications for age-related patterns of substance use.
Each of these trends can be linked to profound changes in the human environment, including social, political and economic changes. Long-term drug use behaviour is an outcome of the interaction between biological, psychological and social factors - no one is predestined to become addicted to drugs.