Drug Abuse - Definitions of dependence and addiction

Dependence and addiction is used to describe the compulsive and uncontrollable use of a substance. The use continues despite negative effects on health, lifestyle, work, or other aspects of one's life. Lack of the substance leads to craving, physical or psychological discomfort, and, at times, an overwhelming desire to obtain more of the substance to alleviate the negative sensations experienced from withdrawal.

Psychological dependence or addiction occurs when the user feels he or she cannot manage without the drug. This can occur for several reasons, with several types of drugs. The condition can be mild or can be extraordinarily severe.

Psychological addiction to painkillers—and this can include ibuprofen (Motrin), aspirin, and acetaminophen (Tylenol)—occurs when the user feels that pain may be too great without regular medication. As pain occurs without use, it fulfills the user's expectations. The pain may be real or may be psychosomatic (triggered by psychological expectations of pain), but it reassures the user that the drug is needed and does good. The problem is that with many types of drug, the effectiveness decreases as use increases.

Psychological addiction can accompany physical addiction, and it is usually difficult to distinguish where psychological needs leave off and physical needs begin. Many addictions are a combination of psychological and physical.

Physical dependence or addiction occurs when the body has developed a physical need for the drug. Physical dependence is usually recognized when the user stops taking the drug. Withdrawal symptoms occur when the body is denied the chemicals to which it has become habituated. Withdrawal symptoms can include dizziness, anxiety, restless sleep, dull ache, acute pain, heart tremors, seizures and convulsions, and heart attack. Sudden withdrawal from some physically addictive drugs can kill the user. Many of the street drugs, such as cocaine and heroin, and many of the prescription drugs, such as Xanax and codeine, can produce severe symptoms if withdrawal is sudden from quantities that were abusive.

Tolerance is the term used for the effect that occurs when the quantity of drug is progressively increased to achieve the desired result. For some chemicals, the body becomes habituated to one quantity and the dosage must be increased to maintain the same level of relief or pleasure experienced from the drug. Increased tolerance for some drugs is what frequently leads to levels that are physically addictive.