ARTICLE | Drug Dependence

Drug Dependence

Drug dependence, a psychological and sometimes physical state characterized by a compulsion to use a drug to experience psychological or physical effects. Drug dependence takes several forms - tolerance, habituation, and addiction.

Drug Dependence

Tolerance, a form of physical dependence occurs when the body becomes accustomed to a drug and requires ever-increasing amounts of it to achieve the same pharmacological effects. This condition is worsened when certain drugs are used at high doses for long periods and may lead to more frequent use of the drug. However, when use of the drug is stopped, drug withdrawal may result which is characterized by nausea, headaches, restlessness, sweating. and difficulty sleeping. The severity of drug withdrawal symptoms varies depending on the drug involved.

Habituation, a form of psychological dependence is characterized by the continued desire for a drug, even after physical dependence is gone. A drug often produces an elated emotional state, and a person abusing drugs soon believes the drug is needed to function at work or home. 

Addiction is a severe craving for the substance and interferes with a person's ability to function normally. It may also involve physical dependence.

Scientists often measure a drug's potential for abuse by conducting studies with laboratory animals. Drugs that an animal administers to itself repeatedly are said to have powerful reinforcing properties and a high potential for abuse. These drugs include some commonly abused substances like opium, alcohol, cocaine, and barbiturates. Other drugs such as marijuana and hallucinogens appear to produce habituation in human although they are not powerful enforcers for laboratory animals.