Substance Abuse and Dependence

Substance abuse is the use of drugs or other substances for a purpose other than the recommended one, usually to cause intoxication or alter mood. Stimulant drugs, solvents, and glue are all commonly abused. Problems may arise due to adverse effects or from the habit-forming potential of the substance.

Drug abuse is the use of a drug for a purpose other than that for which it is normally prescribed or recommended. Commonly abused drugs include stimulant drugs, such as cocaine and amphetamine drugs; central nervous system depressants, such as alcohol and barbiturate drugs; hallucinogenic drugs, such as LSD; and narcotics (see opioid drugs), such as heroin. Some drugs are abused in order to improve performance in sports (see sports, drugs and; steroids, anabolic).

Problems resulting from drug abuse may arise from the adverse effects of the drug, accidents that occur during intoxication, or from the habit-forming potential of many drugs, which may lead to drug dependence. drug addiction Physical or psychological dependence on a drug (see drug dependence).

Drug dependence is the compulsion to continue taking a drug, either to prevent the ill effects that occur when it is not taken, or to produce the desired effects of taking it.

Types of drug dependence

Drug dependence can be psychological or physical, or more commonly both. A person is psychologically dependent if he or she experiences craving or distress when the drug is withdrawn. In physical drug dependence, the body has adapted to the drug, causing the symptoms and signs of withdrawal syndrome when the drug is stopped. These symptoms are relieved if the drug is taken again.


Dependence develops as a result of regular or excessive drug use, and it develops most frequently with drugs that alter mood or behaviour.

Symptoms and signs 

Drug dependence may cause physical problems, for example lung and heart disease from smoking and liver disease from excessive alcohol consumption. Mental problems, such as anxiety and depression, are common during drug withdrawal. Dependence may also be linked with drug tolerance, in which increasing doses of the substance are needed to produce the same effect.


Complications such as hepatitis or AIDS are a particular risk for people who abuse drugs by injection. Death may occur as a result of taking a contaminated drug, or be due to accidental overdose from taking a purer, more potent preparation than usual.

Treatment and outlook 

Controlled withdrawal programmes are available in special centres and hospitals, which usually offer gradual, supervised reductions in dose. Alternative, less harmful drugs may be given, as well as treatment for any withdrawal symptoms. Social service agencies and support groups may provide follow-up care. The success of treatment depends on the motivation of the affected person. Problems often recur if people return to the circumstances that originally gave rise to the drug abuse.

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