Why are drugs addictive?
Addictiveness or addiction forming potential comes down to the question of: what is it about the drug that makes me want to use it again and to keep using it? The connections between the pharmacology of drugs and the psychological consequences are the essence of addictive behaviours.
Psychological manifestations
If drugs have a psychoactive effect then they are potentially addictive. Craving or feeling the need for a psychoactive drug is unlike needing a medicine such as insulin or believing in taking food supplements.
In 'What is addiction?' we defined dependence as a 'psychological state which can be recognised when an individual becomes more preoccupied with substance use, spends more time drinking, smoking or taking other drugs, often at the expense of other important activities'.
These thoughts and behaviours are separate from social constructs, such as legal status, cultural norms, or availability of a drug. Dependence can be confused with other mental health problems, especially anxiety and depression.
What are the pharmacological properties of psychoactive drugs that make them addictive?
The effects of some drugs make them desirable to take again - this is called positive reinforcement.
✔︎ Potency
the stronger the drug effect the more reinforcing
✔︎ Speed of Onset
the faster the drug effect occurs the more reinforcing
✔︎ Duration of Effect
the more quickly the drug effect wears off the sooner the desire to 'top up' occurs; avoiding loss of the drug effect is called negative reinforcement
✔︎ Plasticity
when the drug effect is moulded by the environment in an unpredictable way, it is less reinforcing
Why are drugs addictive
In these slides Duncan covers some basics of the connections between the pharmacology of drugs and the psychology of drug use. This is one of the most interesting aspects of addiction. Duncan looks at four key properties of psychoactive drugs that makes them addictive. See how these principles can be applied.
Duncan Raistrick is a Consultant Addiction Psychiatrist
Physical manifestations
It is sometimes thought that withdrawal symptoms are the hallmark of an addiction. Withdrawal is better understood as a consequence of regular, heavy use of addictive drugs - a strongly learned trigger for continued drinking or drug taking and, therefore, integral to dependence. The important point here is that not all addictive drugs and none of the behavioural addictions cause withdrawal symptoms, albeit there may be some anxiety symptoms in the face of abstaining. In short withdrawal symptoms are not an adequate explanation of addiction.
