Addiction

Historically, addiction has been defined as physical and psychological dependence on psychoactive substances (for example alcohol, tobacco, heroin and other drugs) which cross the blood-brain barrier once ingested, temporarily altering the chemical milieu of the brain.

Addiction can also be viewed as a continued involvement with a substance or activity despite the negative consequences associated with it. Pleasure and enjoyment would have originally been sought, however over a period of time involvement with the substance or activity is needed to feel normal. Some psychology professionals and many laymen now mean 'addiction' to include abnormal psychological dependency on such things as gambling, food, sex, pornography, computers, internet, work, exercise, idolising, watching TV or certain types of non-pornographic videos, spiritual obsession, cutting and shopping.

Drug addiction
The related concept of drug addiction has many different definitions. Some writers give drug addiction to the same meaning as substance dependence, others for example provide drug addiction a narrower meaning which excludes drugs without evidence of tolerance or withdrawal symptoms.

The American Society of Addiction Medicine has this definition for Addiction: Addiction is a primary, chronic disease of brain reward, motivation, memory and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in the individual pursuing reward and/or relief by substance use and other behaviors. The addiction is characterized by impairment in behavioral control, craving, inability to consistently abstain, and diminished recognition of significant problems with one’s behaviors and interpersonal relationships. Like other chronic diseases, addiction involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death.

Substance dependence
According to the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), substance dependence is defined as:


 * "When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This, along with Substance Abuse are considered Substance Use Disorders...."

Substance dependence can be diagnosed with physiological dependence, evidence of tolerance or withdrawal, or without physiological dependence.

DSM-IV substance dependencies:
 * 303.90 Alcohol dependence
 * 304.00 Opioid dependence
 * 304.10 Sedative, hypnotic, or anxiolytic dependence (including benzodiazepine dependence and barbiturate dependence)
 * 304.20 Cocaine dependence
 * 304.30 Cannabis dependence
 * 304.40 Amphetamine dependence (or amphetamine-like)
 * 304.50 Hallucinogen dependence
 * 304.60 Inhalant dependence
 * 304.80 Polysubstance dependence
 * 304.90 Phencyclidine (or phencyclidine-like) dependence
 * 304.90 Other (or unknown) substance dependence
 * 305.10 Nicotine dependence

Behavioral addiction
The term addiction is also sometimes applied to compulsions that are not substance-related, such as compulsive shopping, sex addiction/compulsive sex, overeating, problem gambling and computer addiction. In these kinds of common usages, the term addiction is used to describe a recurring compulsion by an individual to engage in some specific activity, despite harmful consequences, as deemed by the user himself to his individual health, mental state, or social life.