Substance Dependence - Causes

Causes

Drugs known to cause addiction include both legal and illegal drugs as well as prescription or over-the-counter drugs, according to the definition of the American Society of Addiction Medicine.

• Stimulants (psychical addiction, moderate to severe; withdrawal is purely psychological and psychosomatic):
  • Amphetamine and methamphetamine
  • Cocaine
  • Caffeine
  • Nicotine
• Sedatives and hypnotics (psychical addiction, mild to severe, and physiological addiction, severe; abrupt withdrawal may be fatal):
  • Alcohol
  • Barbiturates
  • Benzodiazepines, particularly alprazolam, flunitrazepam, triazolam, temazepam, and nimetazepam Z-drugs like Zimovane have a similar effect in the body to Benzodiazepines.
  • Methaqualone and the related quinazolinone sedative-hypnotics
• Opiate and opioid analgesics (psychical addiction, mild to severe, physiological addiction, mild to severe; abrupt withdrawal is unlikely to be fatal):
  • Morphine and codeine, the two naturally occurring opiate analgesics
  • Semi-synthetic opiates, such as heroin (diacetylmorphine; morphine diacetate), oxycodone, buprenorphine, and hydromorphone
  • Fully synthetic opioids, such as fentanyl, meperidine/pethidine, and methadone

Addictive drugs also include a large number of substrates that are currently considered to have no medical value and are not available over the counter or by prescription.

Several theories of drug addiction exist, some of the main ones being genetic predisposition, the self-medication theory, and factors involved with social/economic development. There are strong associations between poverty and addiction. It has long been established that genetic factors along with social and psychological factors are contributors to addiction. A common theory along these lines is the self-medication hypotheses. Epidemiological studies estimate that genetic factors account for 40–60% of the risk factors for alcoholism. Similar rates of heritability for other types of drug addiction have been indicated by other studies. Knestler hypothesized in 1964 that a gene or group of genes might contribute to predisposition to addiction in several ways. For example, altered levels of a normal protein due to environmental factors could then change the structure or functioning of specific brain circuits during development. These altered brain circuits could change the susceptibility of an individual to an initial drug use experience. In support of this hypothesis, animal studies have shown that environmental factors such as stress can affect an animal's genotype.