Characteristics of Addictive Behaviours

A state of dependency characterised by a strong compulsive need to undergo a certain behaviour, such as taking drugs, drinking alcohol, smoking cigarettes or gambling.
The addict will be unable to resist the addictive behaviour even when negative things will result and will undergo withdrawal with physiological (shaking, sweats, nausea etc) and/or psychological symptoms (irritability, mood swings, cravings) if they are deprived of the behaviour.
The DSM-V used to only include substance addiction, but now also considers gambling and other behaviours to be addictions.
Mark Griffiths suggested six criteria for addictions.

Salience is where the addiction has become the most important thing in somebodies life.
When they are not engaging in the behaviour, they will spend all of their time thinking about it.

When engaging in the behaviour, the individual's mood will change.
This is a form of self medication, however, the same behaviour could be used at different times for a different result (eg. smoking could be used for relaxation or stimulation).
The feeling could be a high, a buzz, a numbness etc.

Over time, the individual will need to partake in the behaviour more and more frequently to maintain the same level of satisfaction, whether this is substance based or not.

If the behaviour is stopped, the addict will go through withdrawal.
They may experience insomnia, headaches, irritability or many other psychological or physiological symptoms.

Addicts will find themselves in conflict with family and friends over their addiction or even losing their job.
They may also have an intrapsychic conflict in that they dont want to be addicted but cannot help themself.

Even if the addict has stopped their addiction, they are likely to return to it, even years later.