Drug abuse or substance abuse refers to the use of certain chemicals for the purpose of creating pleasurable effects on the brain. There are over 190 million drug users around the world and the problem has been increasing at alarming rates, especially among young adults under the age of 30. Apart from the long term damage to the body drug abuse causes, drug addicts who use needles are also at risk of contracting HIV and hepatitis B and C infections.

Causes of drug use

Drugs of abuse are usually psychoactive drugs that are used by people for various different reasons which may include:

• Curiosity and peer pressure, especially among school children and young adults
• The use of prescription drugs that were originally intended to target pain relief may have turned into recreational use and become addictive
• Chemicals may be used as part of religious practices or rituals
• Recreational purposes
• As a means of obtaining creative inspiration

Drug categories

Drugs of abuse fall into three groups and these include:

• Depressants: These cause depression of the brain's faculties and examples include sleeping pills (barbiturates) and heroin.
• Stimulants: These cause stimulation of the brain, giving rise to alertness and increased bursts of activity. A rapid heart rate, dilated pupils, raised blood pressure, nausea or vomiting and behavioural changes such as agitation, and impaired judgement may also result. In severe cases, there may be delusional psychosis which can occur with the use of cocaine and amphetamines.
• Hallucinogens: These cause hallucinations and an "out of this world" feeling of dissociation from oneself. Hallucinogens may cause distorted sensory perception, delusion, paranoia and even depression. Examples includes ecstasy, mescaline and LSD.

Examples of drugs are:

• Alcohol
• Tobacco
• Cocaine from coca
• Opium and opioids from poppy plants
• Hashish or marijuana from cannabis
• Synthetic drugs such as heroin, ecstasy and LSD

Administration

There are several different routes of administration for drugs of abuse including orally in the form of a pill, intravenously in the form of an injection, by inhaling the substance in the from of smoke or via snorting the substance so it is absorbed into the blood vessels of the nose.

Epidemiology of drug abuse

Cannabis, marijuana and hashish are the most widely abused drugs in the world. Around 141 million people worldwide consume cannabis. The use of stimulants such as amphetamine and ecstasy is also widespread, with nearly 30 million people abusing these drugs. Cocaine is used by around 13 million people across the globe, with the highest numbers of users in the United States. Abuse of heroin and other opioids is less common than with other drugs and is taken up by around 8 million people worldwide, mainly in South-East and South-West Asia and Europe.

Drug abuse is seen in various different age groups and in individuals from nearly all walks of life and socioeconomic strata. However, men are more likely to abuse drugs than women, single people are more likely than married individuals and urban dwellers more likely than rural dwellers. Prisoners, street children and younger individuals are also more likely to abuse drugs.