Addiction in Oxford English Dictionary is defined as “the state of being (self-) addicted or given to a habit or pursuit; devotion” and “the state of being addicted to a drug; a compulsion and need to continue taking a drug as a result of taking it in the past”.
Addiction has evolved from being a moral model to being a medical model. For instance, alcoholism used to be regarded as a moral failing and self-directed change was demanded of the user, but it is now considered a legitimate medical condition where the individual is entitled to help by counselling or medication. Alongside this transition was the growing public alarm over excessive drinking and the inclusion of other socially unacceptable drug use. By the 20th century, there was also recognition that non-substance addiction such as gambling had the same psychological dynamics and the same underlying neurochemistry, which were just as overwhelming and dangerous, and could be treated with the same therapies.
Addiction can be viewed on a continuum of severity. Mild forms may be short-lived, situational, sometimes socially acceptable, or episodic, while severe ones may be seen not only as a destructive habit but as a kind of slavery or the loss of one’s soul. People severely addicted not only change what they do but who they are as well. How we “diagnose” a condition can be determined by either using a quantitative threshold (such as using DSM/ICD) or using a cut-off point in a continuous scale (such as AUDIT scoring for alcohol use disorder).
Abuse refers to problematic use with social or occupational impairment, but no significant tolerance or withdrawal whereas dependence emphasises physiological tolerance and withdrawal.
In summary, addiction is a disorder involving a loss of the normal flexibility of human behaviour, leaving a dehumanised state of compulsive activity or overwhelming involvement. It has acquired a range of terms over time, numerously inferring moral weakness. It is associated with psychoactive substances or other pleasurable behaviours and can occur on a spectrum from mild to severe. The term dependence may refer to physiological aspects of addiction (tolerance or withdrawal) but is also used to define the severe end of the spectrum. As a result, the confusion surrounding this terminology has led to it being removed from DSM-5.