Drug addiction

Drug addiction

From Wikipedia, the free encyclopedia


Data from the medical journal The Lancet Data from the medical journal The Lancet[1]

Drug addiction is a condition characterized by compulsive drug intake, craving and seeking, despite what the majority of society may perceive as the negative consequences associated with drug use.[2]

Although being addicted implies drug dependence, it is possible to be dependent on a drug without being addicted. People that take drugs to treat diseases and disorders, which interfere with their ability to function, may experience improvement of their condition.

Such persons are dependent on the drug, but are not addicted. One is addicted, rather than merely dependent, if one exhibits compulsive behavior towards the drug and has difficulty quitting it.

To qualify as being dependent a person must

  • Take a drug regularly
  • Experience unpleasant symptoms if discontinued, which makes stopping difficult.

Substance abuse can occur with or without dependency, and with or without addiction. Substance abuse is any use of a substance, which causes more harm than good.



Components of addiction

Drug addiction has two components: physical dependency, and psychological dependency. Physical dependency occurs when a drug has been used habitually and the body has become accustomed to its effects. The person must then continue to use the drug in order to feel normal, or its absence will trigger the symptoms of withdrawal. Psychological dependency occurs when a drug has been used habitually and the mind has become emotionally reliant on its effects, either to elicit pleasure or relieve pain, and does not feel capable of functioning without it. Its absence produces intense cravings, which are often brought on or magnified by stress. A dependent person may have either aspects of dependency or both.

"Chipping" is also a term used to describe a pattern of drug use in which the user is not physically dependent and sustains 'controlled use' of a drug. This is done by avoiding influences that reinforce dependence, such that the drug is used for relaxation and not for escape. This is similar to the medical term 'recreational substance use'.


History of addiction

The phenomenon of drug addiction has occurred to some degree throughout recorded history (see "opium"), though modern agricultural practices, improvements in access to drugs, advancements in biochemistry, and dramatic increases in the recommendation of drug usage by clinical practitioners have exacerbated the problem significantly in the 20th century. Improved means of active biological agent manufacture and the introduction of synthetic compounds, such as methamphetamine are also factors contributing to drug addiction.


Addictive nature of drugs

The addictive nature of drugs varies from substance to substance, and from individual to individual. Drugs such as codeine or alcohol, for instance, typically require many more exposures to addict their users than drugs such as heroin or cocaine. Likewise, a person who is psychologically or genetically predisposed to addiction is much more likely to suffer from it.

Although dependency on hallucinogens like LSD ("acid") and psilocybin (key hallucinogen in "magic mushrooms") is listed as Substance-Related Disorder in the DSM-IV, most psychologists do not classify them as addictive drugs. Experts on addiction say that the use of LSD and psilocybin causes neither psychological nor physical dependency [citation needed]. Many users report feeling less desire to use these drugs after every use [citation needed].


The basis for addiction

There is a growing viewpoint that drug addiction is a form of dysfunctional learning[citation needed]. Drugs of abuse take over the neurological circuitry involved in motivation and reward. This leads to aberrant learning[citation needed]. Because of this, drug-associated cues can trigger a desire to use, as well as unconscious or compulsive drug-seeking behavior, with the sense that voluntary control over drug use is lost.

The stages of problematic use could be defined as preoccupation/anticipation, binge/intoxication, and withdrawal/negative effect.[3] As drugs activate neuronal pathways in the brain, they get 'laid down' stronger and stronger with each use. These pathways also activate faster with each use. The quicker the effect, or 'high', the stronger the dysfunctional learning. In addition, objects, people, or places also seem to be strongly associated with the drug experience, making them 'triggers' to 'cravings' and increase the chances of further use. Those that favor the biological models of addiction see these neuro-chemical changes in the brain as evidence that addiction is a disease, though research has shown that this learned behavior can be unlearned. Unfortunately, substance abuse also inhibits further learning, meaning continued use makes unlearning more challenging.

Abused drugs can also modulate long-term potentiation (LTP) and long-term depression (LTD) in neuronal circuits associated with the addiction process, suggesting a way for the behavioral consequences of drug-taking to become reinforced by learning mechanisms.[4] Effectively assessing where an individual is in addiction and tailoring treatment to this would make treatment outcomes more effective. This may be why there has been no outstanding results in terms of treatments for addiction with the most significant factor in recovery being the user therapist relationship[3] In addition to determining where someone is in terms of addiction, indications as to where they are in their current cycle of use: Crash, withdrawal or extinction would also inform appropriate treatment interventions.

Animal studies have shown that drug availability (over and above the actual effects of the substance) are associated with stimuli exposure to objects associated with use; these trigger the release of adrenaline (which causes "fight or flight" response). The excitation can be perceived as a 'need' to use.

Glutamate, Dopamine, and Serotonin have long been associated with highly dependent addictions are well established as key to the compulsive behavior related to cocaine and amphetamine use,Norepinephrine, GABA& NMDA are also very important in terms of learning and 'Addiction' With GABA seeming strong in terms of alcohol abuse and the corresponding crash.


Evolutionary psychology view of addiction

It is obvious that genes for addiction would not be directly selected. Since evolution theory claims that every physical and behavioral trait is a direct or side effect of selection, then the capacity to be addicted to drugs must be a side effect of something that was selected.

A number of writers including Keith Henson [4] have suggested that the capacity to be addicted to drugs is a side effect of social attention rewards. It is easy to understand how sensitivity to social rewards would evolve in social primates. For example, Jane Goodall's observation that chimpanzees who hunt get additional mating opportunities. The proposed evolved mechanism for social rewards is that attention causes the release of endorphins and dopamine into the brain's reward circuits.

It seems that addictive drugs activate brain reward circuits that are normally activated by attention, without the need to kill a large, dangerous animal and drag it back to camp (or modern equivalents).


The chemicals responsi

The CREB protein, a transcription factor activated by cyclic adenosine monophosphate (cAMP) immediately after a high, triggers genes that produce proteins such as dynorphin, which cuts off dopamine release and temporarily inhibits the reward circuit. In chronic drug users, a sustained activation of CREB leaves the user feeling depressed and dissatisfied, and unable to find pleasure in previously enjoyable activities, often leading to a return to the drug for an additional "fix". It also leads to a short term tolerance of the substance, necessitating that a greater amount be taken in order to reach the same high.

Another transcription factor, known as delta FosB, is thought to activate genes that, counter to the effects of CREB, actually increase the user's sensitivity to the effects of the substance. Delta FosB slowly builds up with each exposure to the drug and remains activated for weeks after the last exposure—long after the effects of CREB have faded. The hypersensitivity that it causes is thought to be responsible for the intense cravings associated with drug addiction, and is often extended to even the peripheral cues of drug use, such as related behaviors or the sight of drug paraphernalia. There is some evidence that delta FosB even causes structural changes within the nuclear accumbens, which presumably helps to perpetuate the cravings, and may be responsible for the high incidence of relapse that occur in treated drug addicts.

Regulator of G-protein Signaling 9-2 (RGS 9-2) has recently been the subject of several animal knockout studies. Animals lacking RGS 9-2 appear to have increased sensitivity to dopamine receptor agonists such as cocaine and amphetamines; over-expression of RGS 9-2 causes a lack of responsiveness to these same agonists. RGS 9-2 is believed to catalyze inactivation of the G-protein coupled D2 receptor by enhancing the rate of GTP hydrolysis of the G alpha subunit which transmits signals into the interior of the cell.


Mechanisms of effect

The mechanisms by which different substances activate the reward system vary among drug classes.

  • Depressants such as alcohol and benzodiazepines work by increasing the affinity of the GABA receptor for its ligand; GABA. Narcotics such as morphine and methadone, work by mimicking endorphins—chemicals produced naturally by the body which have effects similar to dopamine—or by disabling the neurons that normally inhibit the release of dopamine. These substances (sometimes called "downers") typically facilitate relaxation and pain-relief.
  • Stimulants such as amphetamines, nicotine, and cocaine, increase dopamine signaling, either by directly stimulating its release, or by blocking its absorption (see "reuptake"). These substances (sometimes called "uppers") typically cause heightened alertness and energy. They cause a pleasant feeling in the head known as a high. This high wears off leaving the user feeling depressed. This makes them want more of the drug or the addiction.

The most common drug addictions are to legal substances such as:

Many prescription or over the counter drugs are extremely addictive or can become so if misused. Steroidal medications, for example, are extremely addictive[citation needed] as well as benzodiazapines occasionally prescribed as sleeping tablets e.g valium. In addition, a large number of other substances, which are currently considered to have no medical value and are not available over the counter or by prescription. Depending on the jurisdiction, these drugs may be legal only as part of a government sponsored study, illegal to use for any purpose, illegal to sell, or even illegal to merely possess.

In 1972, United States President Richard Nixon declared a war on illegal drugs in an attempt to control the growing problem of drug addiction and drug-related crime. It is unclear, though, whether laws against drugs do anything to stem usage and dependency. In jurisdictions where addictive drugs are illegal, they are generally supplied by drug dealers, who are often involved with organized crime. Even though the cost of producing most illegal addictive substances is very low, their illegality combined with the addict's need permits the seller to command a premium price, often hundreds of times the production cost. As a result, the addict sometimes turns to crime to support their habit.


Recovery from drug addiction

Methods of recovery from addiction to drugs vary widely according to the types of drugs involved, amount of drugs used, duration of the drug addiction, medical complications and the social needs of the individual. Treatment is just as important for the addicted individual as for the significant others in the addicted individuals sphere of contact.

One of many recovery methods is the 12 step recovery program, with prominent examples including Alcoholics Anonymous and Narcotics Anonymous. They are commonly known and used for a variety of addictions for the individual addicted and the family of the individual. Substance-abuse rehabilitation (or "rehab") centers frequently offer a residential treatment program for the seriously addicted in order to isolate the patient from drugs and interactions with other users and dealers. Outpatient clinics usually offer a combination of individual counseling and group counseling. Frequently a physician or psychiatrist will assist with prescriptions to assist with the side effects of the addiction (the most common side effect that the medications can help is anxiety).

Residential drug treatment can be broadly divided into two camps: 12 step programs or Therapeutic Communities. 12 step programmes have the advantage of coming with an instant social support network though some find the spiritual context not to their taste. In the UK drug treatment is generally moving towards a more integrated approach with rehabs offering a variety of approaches. These other programs may use Cognitive-Behavioral Therapy an approach that looks at the relationship between thoughts feelings and behaviours, recognising that a change in any of these areas can affect the whole. CBT sees addiction as a behaviour rather than a disease and subsequently curable, or rather, unlearnable. CBT programmes recognise that for some individuals controlled use is a more realistic possibility.

Other forms of treatment involve replacement drugs such as methadone. Although methadone is itself addictive, opioid dependency is often so strong that a way to stabilise levels of opioid needed and a way to gradually reduce the levels of opioid needed are required. Other treatments, such as acupuncture, may be used to help alleviate symptoms as well. However, In 1997, the following statement was adopted as policy of the American Medical Association (AMA) after a report on a number of alternative therapies including acupuncture:

There is little evidence to confirm the safety or efficacy of most alternative therapies. Much of the information currently known about these therapies makes it clear that many have not been shown to be efficacious. Well-designed, stringently controlled research should be done to evaluate the efficacy of alternative therapies.

Determining the best type of recovery program for an addicted person depends on a number of factors, including: personality, drug(s) of addiction, concept of spirituality or religion, mental or physical illness, and local availability and affordability of programs.

Ibogaine is an (unpleasant) psychoactive drug that specifically interrupts the addictive response, and is currently being studied for its effects upon cocaine, heroin, nicotine, and SSRI addicts. Alternative medicine clinics offering ibogaine treatment have appeared along the U.S. border.

Many different ideas circulate regarding what is considered a "successful" outcome in the recovery from addiction. It has widely been established that abstinence from addictive substances is generally accepted as a "successful" outcome.


Medical definitions

The 1957 World Health Organization (WHO) Expert Committee on Addiction-Producing Drugs defined addiction and habituation as components of drug abuse:

Drug addiction is a state of periodic or chronic intoxication produced by the repeated consumption of a drug (natural or synthetic). Its characteristics include: (i) an overpowering desire or need (compulsion) to continue taking the drug and to obtain it by any means; (ii) a tendency to increase the dose; (iii) a psychic (psychological) and generally a physical dependence on the effects of the drug; and (iv) detrimental effects on the individual and on society.

Drug habituation (habit) is a condition resulting from the repeated consumption of a drug. Its characteristics include (i) a desire (but not a compulsion) to continue taking the drug for the sense of improved well-being which it engenders; (ii) little or no tendency to increase the dose; (iii) some degree of psychic dependence on the effect of the drug, but absence of physical dependence and hence of an abstinence syndrome [withdrawal], and (iv) detrimental effects, if any, primarily on the individual.

In 1964, a new WHO committee found these definitions to be inadequate, and suggested using the blanket term "drug dependence":

The definition of addiction gained some acceptance, but confusion in the use of the terms addiction and habituation and misuse of the former continued. Further, the list of drugs abused increased in number and diversity. These difficulties have become increasingly apparent and various attempts have been made to find a term that could be applied to drug abuse generally. The component in common appears to be dependence, whether psychic or physical or both. Hence, use of the term 'drug dependence', with a modifying phase linking it to a particular drug type in order to differentiate one class of drugs from another, had been given most careful consideration. The Expert Committee recommends substitution of the term 'drug dependence' for the terms 'drug addiction' and 'drug habituation'.

The committee did not clearly define dependence, but did go on to clarify that there was a distinction between physical and psychological ("psychic") dependence. It said that drug abuse was "a state of psychic dependence or physical dependence, or both, on a drug, arising in a person following administration of that drug on a periodic or continued basis." Psychic dependence was defined as a state in which "there is a feeling of satisfaction and psychic drive that requires periodic or continuous administration of the drug to produce pleasure or to avoid discomfort" and all drugs were said to be capable of producing this state:

There is scarcely any agent which can be taken into the body to which some individuals will not get a reaction satisfactory or pleasurable to them, persuading them to continue its use even to the point of abuse — that is, to excessive or persistent use beyond medical need.

The 1957 and 1964 definitions of addiction, dependence and abuse persist to the present day in medical literature. It should be noted that at this time (2006) the Diagnostic Statistical Manual (DSM IVR) now spells out specific criteria for defining abuse and dependence.

In 2001, the American Academy of Pain Medicine, the American Pain Society, and the American Society of Addiction Medicine jointly issued "Definitions Related to the Use of Opioids for the Treatment of Pain," which defined the following terms:

Addiction is a primary, chronic, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. It is characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving.

Physical dependence is a state of adaptation that is manifested by a drug class specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist.

Tolerance is the body's physical adaptation to a drug: greater amounts of the drug are required over time to achieve the initial effect as the body "gets used to" and adapts to the intake.

Pseudoaddiction is a term which has been used to describe patient behaviors that may occur when pain is undertreated. Patients with unrelieved pain may become focused on obtaining medications, may “clock watch,” and may otherwise seem inappropriately “drug seeking.” Even such behaviors as illicit drug use and deception can occur in the patient's efforts to obtain relief. Pseudoaddiction can be distinguished from true addiction in that the behaviors resolve when pain is effectively treated.


Substances considered to be addictive (some may be debatable)


Addiction and drug control legislation

Most countries have legislation which brings various drugs and drug-like substances under the control of licensing systems. Typically this legislation covers any or all of the opiates, cannabinoids, cocaine, barbiturates, hallucinogenics and a variety of more modern synthetic drugs, and unlicensed production, supply or possession is a criminal offence.

Usually, however, drug classification under such legislation is not related simply to addictiveness. The substances covered often have very different addictive properties. Some are highly prone to cause physical dependency, whilst others rarely cause any form of compulsive need whatsoever. Also, under legislation specifically about drugs, alcohol is not usually included.

Although the legislation may be justifiable on moral or public health grounds, it can make addiction or dependency a much more serious issue for the individual: reliable supplies of a drug become difficult to secure, and the individual becomes vulnerable to both criminal abuse and legal punishment.


Drug addiction as portrayed in popular media

Narrative Films





See also



  • Sainsbury, Drug and the Drug Habit (New York, 1909)
  • C. A. McBride, Modern Treatment of Alcoholism and Drug Narcotism (New York, 1910)
  • G. E. Pettey, Narcotic Drug Diseases and Allied Ailments (Philadelphia, 1913)
  • Fitz Hugh Ludlow wrote The Hasheesh Eater (1857) and The Opium Habit (1868), designed as a warning.



  1. ^ Nutt, David; King, Leslie A,; Saulsbury, William; Blakemore, Colin (March 24, 2007). ""Development of a rational scale to assess the harm of drugs of potential misuse"". The Lancet 369: 1047-1053. 
  2. ^ "Principles of Drug Addiction Treatment: A Research Based Guide" Preface, National Institute on Drug Abuse
  3. ^ Koob. G.F. 1997; The Neurobiology of Drug Addiction. J Neuropsychiatry Clin Neurosci; 9:482-497 [1]
  4. ^ Wolf. M 2002. Addiction: Making the Connection Between Behavioral Changes and Neuronal Plasticity in Specific Pathways Molecular Interventions 2:146-157[2]


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