Addiction is a condition in which the body must have a drug to avoid physical and psychological withdrawal symptoms. Addiction's first stage is dependence, during which the search for a drug dominates an individual's life. An addict eventually develops tolerance, which forces the person to consume larger and larger doses of the drug to get the same effect.

Addiction exerts a long and powerful influence on the brain that manifests in three distinct ways: craving for the object of addiction, loss of control over its use, and continuing involvement with it despite adverse consequences.

In the 1930s, when researchers first began to investigate what caused addictive behaviour, they believed that people who developed addictions were somehow morally flawed or lacking in willpower. Overcoming addiction, they thought, involved punishing miscreants or, alternately, encouraging them to muster the will to break a habit.

The scientific consensus however has changed since then. Today we recognize addiction as a chronic disease that changes both brain structure and function. Just as cardiovascular disease damages the heart and diabetes impairs the pancreas, addiction hijacks the brain. This happens as the brain goes through a series of changes, beginning with recognition of pleasure and ending with a drive toward compulsive behaviour.

The behavioural manifestations and complications of addiction, due to impaired control, can include Impaired Control and Judgement Problems, Cognitive Changes & Emotional changes as below:

Impaired Control and Judgement Problems such as:
  • Engaging in more addictive behaviour than the person intended.
  • Increased time lost from work or school.
  • Continued use despite physical or psychological consequences.
  • Narrowing of the addictive behaviour repertoire.
  • Lack of readiness to get help, despite admitting a problem.
Cognitive Changes such as
  • Preoccupation with substance or addictive behaviour.
  • Altered sense of pros and cons of addictive behaviours.
  • False belief that problems are not predictable consequences of addiction.
Emotional Changes such as
  • Increased anxiety, dysphoria and emotional pain
  • Situations seem more stressful than they really are.
  • Difficulty identifying and expressing feelings.