This article is about interpretation of natural languages. For interpretation of programming languages, see Interpreted language.
"Interpreter" redirects here. For other uses, see Interpreter (disambiguation).
Interpretation or interpreting is a translational activity in which one produces a first and final translation on the basis of a one-time exposure to an utterance in a source language.
The most common two modes of interpreting are simultaneous interpreting, which is done at the time of the exposure to the source language, and consecutive interpreting, which is done at breaks to this exposure.
Interpreting is an ancient human activity which predates the invention of writing. However, the origins of the profession of interpreting date back to less than a century ago.
|Look up interpret in Wiktionary, the free dictionary.|
Many Indo-European languages have words for interpreting and interpreters. Expressions in Germanic, Scandinavian and Slavic languages denoting an interpreter can be traced back to Akkadian, around 1900 BCE. The Akkadian root targumânu/turgumânu also gave rise to the term dragoman via an etymological sideline from Arabic.
The English word ‘interpreter’, however, is derived from Latininterpres (meaning ‘expounder’, ‘person explaining what is obscure’), whose semantic roots are not clear. Some scholars take the second part of the word to be derived from partes or pretium (meaning ‘price’, which fits the meaning of a ‘middleman’, ‘intermediary’ or ‘commercial go-between’), but others have suggested a Sanskrit root.
Simultaneous interpretation (SI) suffers the disadvantage that the interpreter must do the best he or she can within the time permitted by the pace of source speech and the advantages of time-saving and not disturbing the natural flow of the speaker. The most common form is extempore SI, where the interpreter does not know the message until he or she hears it.
Simultaneous interpretation using electronic equipment where the interpreter can hear the speaker's voice as well as the interpreter's own voice was introduced in the Nuremberg trials in 1945. In the Nuremberg trials the languages of interpretation are French, Russian, German and English. As it proved successful, IBM was able to sell the equipment developed to the United Nations.
In the ideal setting for oral language, the interpreter sits in a sound-proof booth and speaks into a microphone, while clearly seeing and hearing the source-language speaker via earphones. The simultaneous interpretation is rendered to the target-language listeners via their earphones.
The first introduction and employment of extempore simultaneous interpretation using electronic equipment that could facilitate large numbers of listeners was the Nuremberg Trials of 1945–1946, with four official working languages. The technology arose in the 1920s and 1930s when American businessman Edward Filene and British engineer Alan Gordon Finlay developed simultaneous interpretation equipment with IBM.
In consecutive interpreting (CI), the speaker is required to pause to allow interpretation. Therefore, the time needed is much greater (possibly double the time needed). Traditionally, the interpreter will sit or stand near the speaker.
Consecutive interpretation can be conducted in a pattern of short or long segments according to the interpreter's preference. In short CI, the interpreter relies mostly on memory whereas, in long CI, most interpreters will rely on note-taking. The notes must be clear and legible in order to not waste time on reading them. Consecutive interpreting of whole thoughts, rather than in small pieces, is desirable so that the interpreter has the whole meaning before rendering it in the target language. This affords a truer, more accurate, and more accessible interpretation than where short CI or simultaneous interpretation is used.
An attempt at consensus about lengths of segments may be reached prior to commencement, depending upon complexity of the subject matter and purpose of the interpretation, though speakers generally face difficulty adjusting to unnatural speech patterns.
On occasion, document sight translation is required of the interpreter during consecutive interpretation work. Sight translation combines interpretation and translation; the interpreter must render the source-language document to the target-language as if it were written in the target language. Sight translation occurs usually, but not exclusively, in judicial and medical work.
Consecutive interpretation may be the chosen mode when bilingual listeners are present who wish to hear both the original and interpreted speech or where, as in a court setting, a record must be kept of both.
When no interpreter is available to interpret directly from source to target, an intermediate interpreter will be inserted in a relay mode, e.g. a Greek source language could be interpreted into English and then from English to another language. This is also commonly known as double-interpretation. Triple-interpretation may even be needed, particularly where rare languages or dialects are involved. Such interpretation can only be effectively conducted using consecutive interpretation.
Since time immemorial, whispering interpretation has been used, known in the trade by the French term chuchotage. To avoid disturbing the original speaker and those present listening to the original speaker, the interpreter's voice is kept at a low volume. To do this, the interpreter and the person requiring interpretation must sit or stand in close proximity to one another. No actual whispering is involved as this is difficult to decipher as well as being too much of a strain on the voice: the interpreter uses normal 'voiced' speech at a low volume. Only one or at the most two people in need of interpretation can be accommodated, unless portable electronic equipment is used.
This form of interpretation puts a strain on the interpreter who has to sit for long periods leaning towards the person in need of interpretation.
Conference interpreting refers to interpretation at a conference or large meeting, either simultaneously or consecutively. The advent of multi-lingual meetings has reduced the amount of consecutive interpretation in the last 20 years.
Conference interpretation is divided between two markets: institutional and private. International institutions (EU, UN, EPO, et cetera), which hold multilingual meetings, often favor interpreting several foreign languages into the interpreters' mother tongues. Local private markets tend to have bilingual meetings (the local language plus another), and the interpreters work both into and out of their mother tongues. These markets are not mutually exclusive. The International Association of Conference Interpreters (AIIC) is the only worldwide association of conference interpreters. Founded in 1953, its membership includes more than 2,800 professional conference interpreters, in more than 90 countries.
See also: Legal translation
Judicial, legal, or court interpreting occurs in courts of justice, administrative tribunals, and wherever a legal proceeding is held (i.e., a police station for an interrogation, a conference room for a deposition, or the locale for taking a sworn statement). Legal interpreting can be the consecutive interpretation of witnesses' testimony, for example, or the simultaneous interpretation of entire proceedings, by electronic means, for one person, or all of the people attending. In a legal context, where ramifications of misinterpretation may be dire, accuracy is paramount. Teams of two or more interpreters, with one actively interpreting and the second monitoring for greater accuracy, may be deployed.
The right to a competent interpreter for anyone who does not understand the language of the court (especially for the accused in a criminal trial) is usually considered a fundamental rule of justice. Therefore, this right is often guaranteed in national constitutions, declarations of rights, fundamental laws establishing the justice system or by precedents set by the highest courts. However, it is not a constitutionally required procedure (in the United States) that a certified interpreter be present at police interrogation. This has been especially controversial in cases where illegal immigrants with no English skills are accused of crimes.
In the US, depending upon the regulations and standards adhered to per state and venue, court interpreters usually work alone when interpreting consecutively, or as a team, when interpreting simultaneously. In addition to practical mastery of the source and target languages, thorough knowledge of law and legal and court procedures is required of court interpreters. They are often required to have formal authorization from the state to work in the courts – and then are called certified court interpreters.[note 1] In many jurisdictions, the interpretation is considered an essential part of the evidence. Incompetent interpretation, or simply failure to swear in the interpreter, can lead to a mistrial.
In escort interpreting, an interpreter accompanies a person or a delegation on a tour, on a visit, or to a meeting or interview. An interpreter in this role is called an escort interpreter or an escorting interpreter.
Also known as community interpreting, is the type of interpreting occurring in fields such as legal, health, and local government, social, housing, environmental health, education, and welfare services. In community interpreting, factors exist which determine and affect language and communication production, such as speech's emotional content, hostile or polarized social surroundings, its created stress, the power relationships among participants, and the interpreter's degree of responsibility – in many cases more than extreme; in some cases, even the life of the other person depends upon the interpreter's work.
Medical interpreting is a subset of public service interpreting, consisting of communication among Healthcare personnel and the patient and their family or among Healthcare personnel speaking different languages, facilitated by an interpreter, usually formally educated and qualified to provide such interpretation services. In some situations medical employees who are multilingual may participate part-time as members of internal language banks. Depending on country/state specific requirements, the interpreter is often required to have some knowledge of medical terminology, common procedures, the patient interview and exam process. Medical interpreters are often cultural liaisons for people (regardless of language) who are unfamiliar with or uncomfortable in hospital, clinical, or medical settings.
For example, in China, there is no mandatory certificate for medical interpreters as of 2012. Most interpretation in hospitals in China is done by doctors, who are proficient in both Chinese and English (mostly) in his/her specialty. They interpret more in academic settings than for communications between doctors and patients. When a patient needs English language service in a Chinese hospital, more often than not the patient will be directed to a staff member in the hospital, who is recognized by his/her colleagues as proficient in English. The actual quality of such service for patients or medical translation for communications between doctors speaking different languages is unknown by the interpreting community as interpreters who lack Healthcare background rarely receive accreditation for medical translation in the medical community. Interpreters working in the Healthcare setting may be considered Allied Health Professionals.
A sign language interpreter must accurately convey messages between two different languages. An interpreter is there for both deaf and hearing individuals. The act of interpreting occurs when a hearing person speaks, and an interpreter renders the speaker's meaning into sign language, or other forms used by the deaf party(ies). The interpreting also happens in reverse: when a deaf person signs, an interpreter renders the meaning expressed in the signs into the oral language for the hearing party, which is sometimes referred to as voice interpreting or voicing. This may be performed either as simultaneous or consecutive interpreting. Skilled sign language interpreters will position themselves in a room or space that allows them to be seen by the deaf participants and heard clearly by hearing participants, as well as be in a position to hear and/or see the speaker or speakers clearly. In some circumstances, an interpreter may interpret from one language to another whether that is English to British Sign Language, English to American Sign Language, Spanish to English to American Sign Language and so on.
Deaf individuals also have the opportunity to work as interpreters. The Deaf individual will team with a hearing counterpart to provide interpretation for deaf individuals who may not know the same sign language used in that country, who have minimal language skills, are developmentally delayed or have other mental and/or physical disabilities which make communication a unique challenge. In other cases the hearing interpreter may interpret in the sign language, whichever kind of sign language the team knows and the deaf team will then interpret into the language in which the individual can understand. They also interpret information from one medium of language into another – for example, when a person is signing visually, the deaf interpreter could be hired to copy those signs into a deaf-blind person's hand and add visual information.
Most interpreters have been formally trained in an Interpreter Training Program (ITP). ITP lengths vary, and are usually two or four years to obtain a degree or certificate. Graduate programs are also available.
In the United States, Sign Language Interpreters have National and State level certifications. The Registry of Interpreters for the Deaf (RID), a non-profit organization, is known for its national recognition and certification process. In addition to training requirements and stringent certification testing, the RID members must abide by a Code of Professional Conduct, Grievance Process and Continuing Education Requirement. There are many interpreter-training programs in the U.S. The Collegiate Commission on Interpreter Education is the body that accredits Interpreter Preparation Programs. A list of accredited programs can be found on the CCIE web site.
European countries and countries elsewhere have their own national association of Sign Language Interpreters. Some countries have more than one national association due to regional or language differences. The European Forum of Sign Language Interpreters (efsli) is the umbrella organization of sign language interpreters in Europe. In Canada, the professional association that recognizes and nationally certifies sign language interpreters is the Association of Visual Language Interpreters of Canada (AVLIC). Under AVLIC holds several affiliate chapters representing a specified region of Canada.
Sign language interpreters encounter a number of linguistic, environmental, interpersonal and intrapersonal factors that can have an effect on their ability to provide accurate interpretation. Studies have found that most interpreter training programs do not sufficiently prepare students for the highly variable day-to-day stresses that an interpreter must manage, and there is an ongoing conversation in the interpreting field as to how to appropriately prepare students for the challenges of the job. Proposed changes include having a more robust definition of what a qualified interpreter should know, as well as a post-graduate internship structure that would allow new interpreters to work with the benefit of supervision from more experienced interpreters, much like the programs in place in medicine, law enforcement, etc.
By its very nature, media interpreting has to be conducted in the simultaneous mode. It is provided particularly for live television coverages such as press conferences, live or taped interviews with political figures, musicians, artists, sportsmen or people from the business circle. In this type of interpreting, the interpreter has to sit in a sound-proof booth where ideally he/she can see the speakers on a monitor and the set. All equipment should be checked before recording begins. In particular, satellite connections have to be double-checked to ensure that the interpreter's voice is not sent back and the interpreter gets to hear only one channel at a time. In the case of interviews recorded outside the studio and some current affairs program, the interpreter interprets what he or she hears on a TV monitor. Background noise can be a serious problem. The interpreter working for the media has to sound as slick and confident as a television presenter.
Media interpreting has gained more visibility and presence especially after the Gulf War. Television channels have begun to hire staff simultaneous interpreters. The interpreter renders the press conferences, telephone beepers, interviews and similar live coverage for the viewers. It is more stressful than other types of interpreting as the interpreter has to deal with a wide range of technical problems coupled with the control room's hassle and wrangling during live coverage.
Interpreting services can be delivered in multiple modalities. The most common modality through which interpreting services are provided is on-site interpreting.
Also called "in-person interpreting" or sometimes colloquialized as "face-to-face", this delivery method requires the interpreter to be physically present in order for the interpretation to take place. In on-site interpreting settings, all of the parties who wish to speak to one another are usually located in the same place. This is by far the most common modality used for most public and social service settings.
Main article: Telephone interpreting
Also referred to as "over-the-phone interpreting," "telephonic interpreting," and "tele-interpreting," telephone interpreting enables interpretation via telephone. The interpreter is added to a conference call. Telephone interpreting may be used in place of on-site interpreting when no on-site interpreter is readily available at the location where services are needed. However, it is more commonly used for situations in which all parties who wish to communicate are already speaking to one another via telephone (e.g. telephone applications for insurance or credit cards, or telephone inquiries from consumers to businesses).
Main articles: Video Relay Service and Video Remote Interpreting
Interpretation services via Video Remote Interpreting (VRI) or a Video Relay Service (VRS) are useful for spoken language barriers where visual-cultural recognition is relevant, and even more applicable where one of the parties is deaf, hard-of-hearing or speech-impaired (mute). In such cases the interpretation flow is normally within the same principal language, such as French Sign Language (FSL) to spoken French and Spanish Sign Language (SSL) to spoken Spanish. Multilingualsign language interpreters, who can also translate as well across principal languages (such as to and from SSL, to and from spoken English), are also available, albeit less frequently. Such activities involve considerable effort on the part of the translator, since sign languages are distinct natural languages with their own construction and syntax, different from the aural version of the same principal language.
With video interpreting, sign language interpreters work remotely with live video and audio feeds, so that the interpreter can see the deaf or mute party, converse with the hearing party and vice versa. Much like telephone interpreting, video interpreting can be used for situations in which no on-site interpreters are available. However, video interpreting cannot be used for situations in which all parties are speaking via telephone alone. VRI and VRS interpretation requires all parties to have the necessary equipment. Some advanced equipment enables interpreters to control the video camera, in order to zoom in and out, and to point the camera toward the party that is signing.
The majority of professional full-time conference interpreters work for phone interpreting agencies, health care institutions, courts, school systems and international organizations like the United Nations, the European Union, or the African Union.
The world's largest employer of interpreters is currently the European Commission, which employs hundreds of staff and freelance interpreters working into the official languages of the European Union and some others. The European Union's other institutions (the European Parliament and the European Court of Justice) have smaller interpreting services.
The United Nations employs interpreters at almost all its sites throughout the world. Because it has only six official languages, however, it is a smaller employer than the European Union.
Interpreters may also work as freelance operators in their local, regional and national communities, or may take on contract work under an interpreting business or service. They would typically take on work as described above.
The U.S. military in Iraq and Afghanistan during the early-21st century employ hundreds of interpreters to assist with its communications with the local population.
No worldwide testing or certification agency exists for all types of interpreters. For conference interpretation, there is the International Association of Conference Interpreters, or AIIC.
Specific regions, countries, or even cities will have their own certification standards. In many cases, graduates of a certain caliber university program acts as a de facto certification for conference interpretation.
The most recognized interpretation certificate in P.R. China is China Accreditation Test for Translation and Interpretation, short for CATTI, which has certificates both for translation and interpretation.
- ^"The Origins of Simultaneous Interpretation Equipment". Infinity Translation Services. Archived from the original on 2017-02-27. Retrieved 2017-09-29.
- ^"Consecutive and Simultaneous Interpretering". www.conference-interpreters.ca. Archived from the original on 2016-10-22. Retrieved 2017-09-29.
- ^Einesman, Floralynn (1999). "Confessions and Culture: The Interaction of Miranda and Diversity". Journal of Criminal Law and Criminology. p. 26. Archived from the original on 2017-09-22. Retrieved 2017-09-29.
- ^Kilgannon, Corey (2005-04-15). "Queens Hospitals Learn Many Ways to Say 'Ah'". The New York Times. Archived from the original on 2015-05-29. Retrieved 2017-09-29.
- ^"Interpreting American Sign Language". National Association of the Deaf. Archived from the original on 2017-07-08. Retrieved 2017-09-29.
- ^Ingram, Robert M. (1978). "Sign Language Interpretation and General Theories of Language, Interpretation and Communication," in Gerver, D. & H. W. Sinaiko (Eds.), Language Interpretation and Communication. London: Plenum Press, 109-117.
- ^"deaf studies". sign.let.ru.nl. Archived from the original on 2013-01-29.
- ^Ingram, Robert M. (1974). "A Communication Model of the Interpreting Process." Journal of Rehabilitation of the Deaf 7:3 (Jan.), 3-9.
- ^"About Interpreting Education Programs". Registry of Interpreters for the Deaf, Inc. Archived from the original on 2014-12-24.
- ^"Accredited Programs". Commission On Collegiate Interpreter Education. Archived from the original on 2017-06-29. Retrieved 2017-09-29.
- ^"Types of Sign Language and Their Development". www.accreditedlanguage.com. Archived from the original on 2017-05-25. Retrieved 2017-09-29.
- ^"About efsli..."efsli.org. Archived from the original on 2012-09-02. Retrieved 2012-08-31.
- ^"Welcome to AVLIC". www.avlic.ca. Archived from the original on 2017-09-24. Retrieved 2017-09-29.
- ^Dean, Robyn, Robert Q Pollard (January 2001). "Application of Demand-Control Theory to Sign Language Interpreting: Implications for Stress and Interpreter Training"(PDF). The Journal of Deaf Studies and Deaf Education. Volume 6, Issue 1: 1–14 – via Oxford University Press.
- ^"What we do". ec.europa.eu. Archived from the original on 2017-02-05. Retrieved 2017-09-29.
- Gaiba, Francesca (1998). The Origins of Simultaneous Interpretation: The Nuremberg Trial. University of Ottawa Press. ISBN 978-0776604572.
- Pöchhacker, Franz (2016). Introducing Interpreting Studies (2nd ed.). Routledge. ISBN 978-0415742726.
- Woodsworth, Judith; Delisle, Jean (2012). Translators through History (Revised ed.). John Benjamins Publishing Company. ISBN 978-9027224514.
- Takeda, Kayoko; Baigorri-Jalón, Jesús (2016). New Insights in the History of Interpreting. John Benjamins Publishing Company. ISBN 978-9027258670.
- ^The majority of state court systems utilize a certification exam developed and administered by the National Center for State Courts. Most non-native speakers of English use the term "sworn interpreter," which is calqued from a civil-law position title common throughout the world. However, there is no common law country[clarification needed] that uses this term.
"Addictive" redirects here. For other uses, see Addiction (disambiguation) and Addictive (disambiguation).
|Addiction and dependence glossary|
Addiction is a brain disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences. Despite the involvement of a number of psychosocial factors, a biological process – one which is induced by repeated exposure to an addictive stimulus – is the core pathology that drives the development and maintenance of an addiction. The two properties that characterize all addictive stimuli are that they are reinforcing (i.e., they increase the likelihood that a person will seek repeated exposure to them) and intrinsically rewarding (i.e., they are perceived as being inherently positive, desirable, and pleasurable).
Addiction is a disorder of the brain's reward system which arises through transcriptional and epigenetic mechanisms and occurs over time from chronically high levels of exposure to an addictive stimulus (e.g., eating food, the use of cocaine, engagement in sexual intercourse, participation in high-thrill cultural activities such as gambling, etc.).ΔFosB, a gene transcription factor, is a critical component and common factor in the development of virtually all forms of behavioral and drug addictions. Two decades of research into ΔFosB's role in addiction have demonstrated that addiction arises, and the associated compulsive behavior intensifies or attenuates, along with the overexpression of ΔFosB in the D1-typemedium spiny neurons of the nucleus accumbens. Due to the causal relationship between ΔFosB expression and addictions, it is used preclinically as an addiction biomarker. ΔFosB expression in these neurons directly and positively regulates drug self-administration and reward sensitization through positive reinforcement, while decreasing sensitivity to aversion.[note 1]
As described by two groups of researchers, addiction exacts an "astoundingly high financial and human toll" on individuals and society as a whole through the direct adverse effects of drugs, associated healthcare costs, long-term complications (e.g., lung cancer with smoking tobacco, liver cirrhosis with drinking alcohol, or meth mouth from intravenous methamphetamine), the functional consequences of altered neural plasticity in the brain, and the consequent loss of productivity. Classic hallmarks of addiction include impaired control over substances or behavior, preoccupation with substance or behavior, and continued use despite consequences. Habits and patterns associated with addiction are typically characterized by immediate gratification (short-term reward), coupled with delayed deleterious effects (long-term costs).
Examples of drug and behavioral addictions include: alcoholism, amphetamine addiction, cocaine addiction, nicotine addiction, opiate addiction, food addiction, gambling addiction, and sexual addiction. The only behavioral addiction recognized by the DSM-5 and the ICD-10 is gambling addiction. The term addiction is misused frequently to refer to other compulsive behaviors or disorders, particularly dependence, in news media. An important distinction between drug addiction and dependence is that drug dependence is a disorder in which cessation of drug use results in an unpleasant state of withdrawal, which can lead to further drug use. Addiction is the compulsive use of a substance or performance of a behavior that is independent of withdrawal.
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Cognitive control and stimulus control, which is associated with operant and classical conditioning, represent opposite processes (i.e., internal vs external or environmental, respectively) that compete over the control of an individual's elicited behaviors. Cognitive control, and particularly inhibitory control over behavior, is impaired in both addiction and attention deficit hyperactivity disorder. Stimulus-driven behavioral responses (i.e., stimulus control) that are associated with a particular rewarding stimulus tend to dominate one's behavior in an addiction.
Stimulus control of behavior
See also: Stimulus control
Cognitive control of behavior
See also: Cognitive control
Main article: Behavioral addiction
The term behavioral addiction correctly refers to a compulsion to engage in a natural reward – which is a behavior that is inherently rewarding (i.e., desirable or appealing) – despite adverse consequences. Preclinical evidence has demonstrated that marked increases in the expression of ΔFosB through repetitive and excessive exposure to a natural reward induces the same behavioral effects and neuroplasticity as occurs in a drug addiction.
Reviews of both clinical research in humans and preclinical studies involving ΔFosB have identified compulsive sexual activity – specifically, any form of sexual intercourse – as an addiction (i.e., sexual addiction). Moreover, reward cross-sensitization between amphetamine and sexual activity, meaning that exposure to one increases the desire for both, has been shown to occur preclinically and clinically as a dopamine dysregulation syndrome; ΔFosB expression is required for this cross-sensitization effect, which intensifies with the level of ΔFosB expression.
Reviews of preclinical studies indicate that long-term frequent and excessive consumption of high fat or sugar foods can produce an addiction (food addiction).
Gambling is a natural reward which is associated with compulsive behavior and for which clinical diagnostic manuals, namely the DSM-5, have identified diagnostic criteria for an "addiction". There is evidence from functional neuroimaging that gambling activates the reward system and the mesolimbic pathway in particular. Similarly, shopping and playing videogames are associated with compulsive behaviors in humans and have also been shown to activate the mesolimbic pathway and other parts of the reward system. Based upon this evidence, gambling addiction, video game addiction and shopping addiction are classified accordingly.
There are a range of genetic and environmental risk factors for developing an addiction that vary across the population. Roughly half of an individual's risk for developing an addiction is derived from genetics, while the other half is derived from the environment. However, even in individuals with a relatively low genetic loading, exposure to sufficiently high doses of an addictive drug for a long period of time (e.g., weeks–months) can result in an addiction. In other words, anyone can become an addict under the right circumstances.
It has long been established that genetic factors along with environmental (e.g., psychosocial) factors are significant contributors to addiction vulnerability. 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 neurons during development. These altered brain neurons 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.
Overall, the data implicating specific genes in the development of drug addiction is mixed for most genes. One reason for this may be that the case is due to a focus of current research on common variants. Many addiction studies focus on common variants with an allele frequency of greater than 5% in the general population, however when associated with disease, these only confer a small amount of additional risk with an odds ratio of 1.1–1.3 percent. On the other hand, the rare variant hypothesis states that genes with low frequencies in the population (<1%) confer much greater additional risk in the development of disease.
Genome-wide association studies (GWAS) are a recently developed research method which are used to examine genetic associations with dependence, addiction, and drug use. These studies employ an unbiased approach to finding genetic associations with specific phenotypes and give equal weight to all regions of DNA, including those with no ostensible relationship to drug metabolism or response. These studies rarely identify genes from proteins previously described via animal knockout models and candidate gene analysis. Instead, large percentages of genes involved in processes such as cell adhesion are commonly identified. This is not to say that previous findings, or the GWAS findings, are erroneous. The important effects of endophenotypes are typically not capable of being captured by these methods. Furthermore, genes identified in GWAS for drug addiction may be involved either in adjusting brain behavior prior to drug experiences, subsequent to them, or both. 
A study that highlights the significant role genetics play in addiction is the twin studies. Twins have similar and sometimes identical genetics. Analyzing these genes in relation to genetics has helped geneticists understand how much of a role genes play in addiction. Studies performed on twins found that rarely did only one twin have an addiction. In most cases where at least one twin suffered from an addiction, both did, and often to the same substance.
Environmental risk factors for addiction are the experiences of an individual during their lifetime that interact with the individual's genetic composition to increase or decrease the his or her vulnerability to addiction. A number of different environmental factors have been implicated as risk factors for addiction, including various psychosocial stressors; however, an individual's exposure to an addictive drug is by far the most significant environmental risk factor for addiction. The National Institute on Drug Abuse cites lack of parental supervision, the prevalence of peer substance use, drug availability, and poverty as risk factors for substance use among children and adolescents.
Adverse childhood experiences (ACEs) are various forms of maltreatment and household dysfunction experienced in childhood. The Adverse Childhood Experiences Study by the Centers for Disease Control and Prevention has shown a strong dose–response relationship between ACEs and numerous health, social, and behavioral problems throughout a person's lifespan, including those associated with substance abuse. Children's neurological development can be permanently disrupted when they are chronically exposed to stressful events such as physical, emotional, or sexual abuse, physical or emotional neglect, witnessing violence in the household, or a parent being incarcerated or suffering from a mental illness. As a result, the child's cognitive functioning or ability to cope with negative or disruptive emotions may be impaired. Over time, the child may adopt substance use as a coping mechanism, particularly during adolescence. A study of 900 court cases involving children who experienced abuse found that a vast amount of them went on to suffer from some form of addiction in their adolescence or adult life. This pathway towards addiction that is opened through stressful experiences during childhood can be avoided by a change in environmental factors throughout an individuals life and opportunities of professional help.
Adolescence represents a period of unique vulnerability for developing addiction. In adolescence, the incentive–rewards systems in the brain mature well before the cognitive control center. This consequentially grants the incentive–rewards systems a disproportionate amount of power in the behavioral decision making process. Therefore, adolescents are increasingly likely to act on their impulses and engage in risky, potentially addicting behavior before considering the consequences. Not only are adolescents more likely to initiate and maintain drug use, but once addicted they are more resistant to treatment and more liable to relapse. Statistics have shown that those who start to drink alcohol at a younger age are more likely to become dependent later on. About 33% of the population tasted their first alcohol between the ages of 15 and 17, while 18% experienced it prior to this. As for alcohol abuse or dependence, the numbers start off high with those who first drank before they were 12 and then drop off after that. For example, 16% of alcoholics began drinking prior to turning 12 years old, while only 9% first touched alcohol between 15 and 17. This percentage is even lower, at 2.6%, for those who first started the habit after they were 21.
Most individuals are exposed to and use addictive drugs for the first time during their teenage years. In the United States, there were just over 2.8 million new users of illicit drugs in 2013, or about 7,800 new users per day. Over half (54.1 percent) were under 18 years of age.
Individuals with comorbid (i.e., co-occurring) mental health disorders such as depression, anxiety, attention-deficit/hyperactivity disorder (ADHD) or post-traumatic stress disorder are more likely to develop substance use disorders. The National Institute on Drug Abuse cites early aggressive behavior as a risk factor for substance use.
Transgenerational epigenetic factors
See also: Transgenerational epigenetic inheritance
Epigenetic genes and their products (e.g., proteins) are the key components through which environmental influences can affect the genes of an individual; they also serve as the mechanism responsible for the transgenerational epigenetic inheritance of behavioral phenotypes, a phenomenon in which environmental influences on the genes of a parent can affect the associated traits and behavioral phenotypes of their offspring (e.g., behavioral responses to certain environmental stimuli). In addiction, epigenetic mechanisms play a central role in the pathophysiology of the disease; it has been noted that some of the alterations to the epigenome which arise through chronic exposure to addictive stimuli during an addiction can be transmitted across generations, in turn affecting the behavior of one's children (e.g., the child's behavioral responses to addictive drugs and natural rewards). More research is needed to determine the specific epigenetic mechanisms and the nature of heritable behavioral phenotypes that arise from addictions in humans. Based upon preclinical evidence with lab animals, the addiction-related behavioral phenotypes that are transmitted across generations may serve to increase or decrease the child's risk of developing an addiction.
|Transcription factor glossary|
Signaling cascade in the nucleus accumbens that results in psychostimulant addiction
This diagram depicts the signaling events in the brain's reward center that are induced by chronic high-dose exposure to psychostimulants that increase the concentration of synaptic dopamine, like amphetamine, methamphetamine, and phenethylamine. Following presynaptic dopamine and glutamateco-release by such psychostimulants,postsynaptic receptors for these neurotransmitters trigger internal signaling events through a cAMP-dependent pathway and a calcium-dependent pathway that ultimately result in increased CREB phosphorylation. Phosphorylated CREB increases levels of ΔFosB, which in turn represses the c-Fos gene with the help of corepressors;c-Fosrepression acts as a molecular switch that enables the accumulation of ΔFosB in the neuron. A highly stable (phosphorylated) form of ΔFosB, one that persists in neurons for 1–2 months, slowly accumulates following repeated high-dose exposure to stimulants through this process. ΔFosB functions as "one of the master control proteins" that produces addiction-related structural changes in the brain, and upon sufficient accumulation, with the help of its downstream targets (e.g., nuclear factor kappa B), it induces an addictive state.
Chronic addictive drug use causes alterations in gene expression in the mesocorticolimbic projection. The most important transcription factors that produce these alterations are ΔFosB, cAMP response element binding protein (CREB), and nuclear factor kappa B (NF-κB). ΔFosB is the most significant biomolecular mechanism in addiction because the overexpression of ΔFosB in the D1-typemedium spiny neurons in the nucleus accumbens is necessary and sufficient for many of the neural adaptations and behavioral effects (e.g., expression-dependent increases in drug self-administration and reward sensitization) seen in drug addiction. ΔFosB expression in nucleus accumbensD1-typemedium spiny neurons directly and positively regulates drug self-administration and reward sensitization through positive reinforcement while decreasing sensitivity to aversion.[note 1] Specific drug addictions in which ΔFosB has been implicated in addictions to alcohol, amphetamine, cannabinoids, cocaine, methylphenidate, nicotine, phenylcyclidine, propofol, opiates, and substituted amphetamines, among others.ΔJunD, a transcription factor, and G9a, a histone methyltransferase, both oppose the function of ΔFosB and inhibit increases in its expression. Increases in nucleus accumbens ΔJunD expression (via viral vector-mediated gene transfer) or G9a expression (via pharmacological means) reduces, or with a large increase can even block, many of the neural and behavioral alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB).
ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise. Natural rewards, like drugs of abuse, induce gene expression of ΔFosB in the nucleus accumbens, and chronic acquisition of these rewards can result in a similar pathological addictive state through ΔFosB overexpression. Consequently, ΔFosB is the key transcription factor involved in addictions to natural rewards (i.e., behavioral addictions) as well; in particular, ΔFosB in the nucleus accumbens is critical for the reinforcing effects of sexual reward. Research on the interaction between natural and drug rewards suggests that dopaminergic psychostimulants (e.g., amphetamine) and sexual behavior act on similar biomolecular mechanisms to induce ΔFosB in the nucleus accumbens and possess bidirectional cross-sensitization effects that are mediated through ΔFosB. This phenomenon is notable since, in humans, a dopamine dysregulation syndrome, characterized by drug-induced compulsive engagement in natural rewards (specifically, sexual activity, shopping, and gambling), has also been observed in some individuals taking dopaminergic medications.
ΔFosB inhibitors (drugs or treatments that oppose its action) may be an effective treatment for addiction and addictive disorders.
The release of dopamine in the nucleus accumbens plays a role in the reinforcing qualities of many forms of stimuli, including naturally reinforcing stimuli like palatable food and sex. Altered dopamine neurotransmission is frequently observed following the development of an addictive state. In humans and lab animals that have developed an addiction, alterations in dopamine or opioid neurotransmission in the nucleus accumbens and other parts of the striatum are evident. Studies have found that use of certain drugs (e.g., cocaine) affect cholinergic neurons that innervate the reward system, in turn affecting dopamine signaling in this region.
Summary of addiction-related plasticity
Main article: Reward system
This section needs expansion. You can help by adding to it.(August 2015)
Understanding the pathways in which drugs act and how drugs can alter those pathways is key when examining the biological basis of drug addiction. The reward pathway, known as the mesolimbic pathway, or its extension, the mesocorticolimbic pathway, is characterized by the interaction of several areas of the brain.
- The projections from the ventral tegmental area (VTA) are a network of dopaminergicneurons with co-localized postsynaptic glutamate receptors (AMPAR and NMDAR). These cells respond when stimuli indicative of a reward are present. The VTA supports learning and sensitization development and releases DA into the forebrain. These neurons also project and release DA into the nucleus accumbens, through the mesolimbic pathway. Virtually all drugs causing drug addiction increase the dopamine release in the mesolimbic pathway, in addition to their specific effects.
- The nucleus accumbens (NAcc) is one output of the VTA projections. The nucleus accumbens itself consists mainly of GABAergicmedium spiny neurons (MSNs). The NAcc is associated with acquiring and eliciting conditioned behaviors, and is involved in the increased sensitivity to drugs as addiction progresses. Overexpression of ΔFosB in the nucleus accumbens is a necessary common factor in essentially all known forms of addiction; ΔFosB is a strong positive modulator of positively reinforced behaviors.
- The prefrontal cortex, including the anterior cingulate and orbitofrontal cortices, is another VTA output in the mesocorticolimbic pathway; it is important for the integration of information which helps determine whether a behavior will be elicited. It is also critical for forming associations between the rewarding experience of drug use and cues in the environment. Importantly, these cues are strong mediators of drug-seeking behavior and can trigger relapse even after months or years of abstinence.
Other brain structures that are involved in addiction include:
- The basolateral amygdala projects into the NAcc and is thought to also be important for motivation.
- The hippocampus is involved in drug addiction, because of its role in learning and memory. Much of this evidence stems from investigations showing that manipulating cells in the hippocampus alters dopamine levels in NAcc and firing rates of VTA dopaminergic cells.
Role of dopamine and glutamate
Dopamine is the primary neurotransmitter of the reward system in the brain. It plays a role in regulating movement, emotion, cognition, motivation, and feelings of pleasure. Natural rewards, like eating, as well as recreational drug use cause a release of dopamine, and are associated with the reinforcing nature of these stimuli. Nearly all addictive drugs, directly or indirectly, act upon the brain's reward system by heightening dopaminergic activity.
Excessive intake of many types of addictive drugs results in repeated release of high amounts of dopamine, which in turn affects the reward pathway directly through heightened dopamine receptor activation. Prolonged and abnormally high levels of dopamine in the synaptic cleft can induce receptor downregulation in the neural pathway. Downregulation of mesolimbic dopamine receptors can result in a decrease in the sensitivity to natural reinforcers.
Drug seeking behavior is induced by glutamatergic projections from the prefrontal cortex to the nucleus accumbens. This idea is supported with data from experiments showing that drug seeking behavior can be prevented following the inhibition of AMPA glutamate receptors and glutamate release in the nucleus accumbens.
|Neural effects||Behavioral effects|
|c-Fos||↓||Molecular switch enabling the chronic|
induction of ΔFosB[note 2]