❝ the link between pharmacology and psychology is what addiction is all about ❞

Drugs are potentially addictive if they have a psychoactive effect. People may then feel a craving or need for more of the drug. This is unlike needing a medicine such as insulin or believing in a health need to take vitamins.


Addiction is an umbrella term covering substance use and associated health and social consequences. On the 'What is addiction?' page we defined dependence as a 'psychological state which can be recognised when an individual becomes more preoccupied with substance use, spending more time drinking, smoking or taking other drugs, often at the expense of other important activities'. Why are some drugs more likely than others to lead to dependence? The characteristics of some drugs make reinforcement of their use stronger than for other drugs. These characteristics are not to be confused with social constructs, such as legal status, or cultural norms, such as availability of a drug. There are four important properties of a drug which you can apply these criteria to any psychoactive substance and predict its addictiveness - more correctly its dependence forming potential...


The psychology

Dependence is all about what psychologists call reinforcement. What this means is how much am I likely to want to repeat a behaviour - in this case the behaviour is substance use. We have already said that, for all practical purposes, there needs to be a desirable psychoactive effect. It is the pharmacological properties of drugs that explain why drugs with similar effects differ: for example heroin is more addictive than codeine, cocaine is more addictive than caffeine, and yet each pair of drugs belong to the same drug group (opiates and stimulants). The slide show explains the link between the pharmacology and psychology of dependence...

The physical manifestations of addiction

Some scientists see addiction as a brain disorder - a condition where there is deficiency of some neurotransmitter chemicals. It is possible that this is the case for a small number of individuals but for the majority brain abnormalities are consequences rather than causes of addiction. The brain scans pictured in the slide show illustrate how addictive behaviours lead to reduced brain activity and, therefore, the desire to take to activities that pep up these brain functions...

Slideshow: if you are interested in the science, take a look at the slideshow. It will take 40mins to go through all the slides so get comfortable and give yourself plenty of time to digest the learning points, or you might want to have more than one sitting to take it all in  [Best to view full screen].