Classification of problem drinking as a disease
Medical condition
The modern disease theory of alcoholism states that problem drinking is sometimes caused by a disease of the brain, characterized by altered brain structure and function. Today, alcohol use disorder (AUD) is used as a more scientific and suitable approach to alcohol dependence and alcohol-related problems. 
The largest association of physicians – the American Medical Association (AMA) – declared that alcoholism was an illness in 1956. In 1991, the AMA further endorsed the dual classification of alcoholism by the International Classification of Diseases under both psychiatric and medical sections.
Theory.
Under the model of alcoholism, alcohol use disorder is viewed as chronic problem for which abstinence is required. A brain disease model of addiction, based on the extent of neuroadaptation and impaired control, is main position advanced for proposing a disease model of alcohol use disorder. However, if managed properly, damage to the brain can be stopped and to some extent reversed.  In addition to problem drinking, the disease is characterized by symptoms including an impaired control over alcohol, compulsive thoughts about alcohol, and distorted thinking. Alcoholism can also lead indirectly, through excess consumption, to physical dependence on alcohol, and diseases such as cirrhosis of the liver.
The risk of developing alcoholism depends on many factors, such as environment. Those with a family history of alcoholism are more likely to develop it themselves (Enoch &amp; Goldman, 2001); however, many individuals have developed alcoholism without a family history of the disease. Since the consumption of alcohol is necessary to develop alcoholism, the availability of and attitudes towards alcohol in an individual's environment affect their likelihood of developing the disease. Current evidence indicates that in both men and women, alcoholism is 50–60% genetically determined, leaving 40-50% for environmental influences.
In a review in 2001, McLellan et al. compared the diagnoses, heritability, etiology (genetic and environmental factors), pathophysiology, and response to treatments (adherence and relapse) of drug dependence vs type 2 diabetes mellitus, hypertension, and asthma. They found that genetic heritability, personal choice, and environmental factors are comparably involved in the etiology and course of all of these disorders, providing evidence that drug (including alcohol) dependence is a chronic medical illness.
Genetics and environment.
According to the theory, genes play a strong role in the development of alcoholism.
Twin studies, adoption studies, and artificial selection studies have shown that a person's genes can predispose them to developing alcoholism. Evidence from twin studies show that concordance rates for alcoholism are higher for monozygotic twins than dizygotic twins—76% for monozygotic twins and 61% for dizygotic twins. However, female twin studies demonstrate that females have much lower concordance rates than males. Reasons for gender differences may include environmental factors, such as negative public attitudes towards female drinkers.
Adoption studies also suggest a strong genetic tendency towards alcoholism. Studies on children separated from their biological parents demonstrates that sons of alcoholic biological fathers were more likely to become alcoholic, even though they have been separated and raised by non alcoholic parents.
In artificial selection studies, specific strains of rats were bred to prefer alcohol. These rats preferred drinking alcohol over other liquids, resulting in a tolerance for alcohol and exhibited a physical dependency on alcohol. Rats that were not bred for this preference did not have these traits. Upon analyzing the brains of these two strains of rats, it was discovered that there were differences in chemical composition of certain areas of the brain. This study suggests that certain brain mechanisms are more genetically prone to alcoholism.
The convergent evidence from these studies present a strong case for the genetic basis of alcoholism.
History.
Historians debate who has primacy in arguing that habitual drinking carried the characteristics of a disease. Some note that Scottish physician Thomas Trotter was the first to characterize excessive drinking as a mental disease or medical defect.
Others point to American physician Benjamin Rush (1745–1813), a signatory to the United States Declaration of Independence, who understood drunkenness to be what we would now call a "loss of control", as possibly the first to use the term "addiction" in this sort of meaning.
 ;templatestyles src="Template:Blockquote/styles.css" / ;My observations authorize me to say, that persons who have been addicted to them, should abstain from them suddenly and entirely. 'Taste not, handle not, touch not' should be inscribed upon every vessel that contains spirits in the house of a man, who wishes to be cured of habits of intemperance.
Rush argued that "habitual drunkenness should be regarded not as a bad habit but as a disease", describing it as "a palsy of the will". Rush expounded his views in a book published in 1808. His views are described by Valverde, Levine Spode, and Perkins-McVey. Already in 1802 the prominent German physician Christoph Wilhelm Hufeland had published a book on the “brandy plague” stating that the “infection” with spirits makes it “inevitably necessary to drink ever more.” Later he wrote an enthusiastic preface to the book "On the addiction to drink and a rational cure of it" by German-Russian physician C. von Brühl-Cramer. As Spode points out, this study marked the birth of a consistent "paradigm" of addiction as a mental illness, although it took many decades until this view was accepted. Perkins-McVey argues that Rush, Trotter, and Brühl-Cramer each independently developed their own disease theories of alcoholism as a result of their shared interest in the Brunonian system of medicine, which classified alcohol as a stimulant of the vital force. As Perkins-McVey argues, this "understanding of the disease of habitual drunkenness as a phenomena ["sic"] of stimulus dependence is arguably the primary vehicle driving the disease model in the works of Rush, Trotter, and Brühl-Cramer." This shifts the discussion away from the question of historical priority, instead identifying a common conceptual influence on early disease theorists.
In 1849, Swedish physician Magnus Huss coined the term "alcoholism" in his book "Alcoholismus chronicus". Some argue he was the first to systematically describe the physical characteristics of habitual drinking and claim that it was a mental disease. However, Huss regarded heavy drinking still as a vice (that causes a destruction of the nervous system). Moreover, this came decades after Trotter, Rush, Hufeland and Brühl-Cramer wrote their works, and some historians argue that the idea that habitual drinking was a mental disease emerged even earlier.
Given this controversy, the best one can say is that the idea that habitual alcohol drinking was a disease had become more acceptable by the second half of the nineteenth century, although many writers still argued it was a vice, a sin, and not the purview of medicine but of religion.
Between 1980 and 1991, medical organizations, including the AMA, worked together to establish policies regarding their positions on the disease theory. These policies were developed in 1987 in part because third-party reimbursement for treatment was difficult or impossible unless alcoholism were categorized as a disease. The policies of the AMA, formed through consensus of the federation of state and specialty medical societies within their House of Delegates, state, in part: "The AMA endorses the proposition that drug dependencies, including alcoholism, are diseases and that their treatment is a legitimate part of medical practice."
In 1991, the AMA further endorsed the dual classification of alcoholism by the International Classification of Diseases under both psychiatric and medical sections.
Controlled drinking.
The disease theory is often interpreted as implying that problem drinkers are incapable of returning to 'normal' problem free drinking, and therefore that treatment should focus on total abstinence. Some critics have used evidence of controlled drinking in formerly dependent drinkers to dispute the disease theory of alcoholism.
The first major empirical challenge to this interpretation of the disease theory followed a 1962 study by Dr. D. L. Davies. Davies' follow-up of ninety-three problem drinkers found that seven of them were able to return to "controlled drinking" (less than seven drinks per day for at least seven years). Davies concluded that "the accepted view that no alcohol addict can ever again drink normally should be modified, although all patients should be advised to aim at total abstinence"; After the Davies study, several other researchers reported cases of problem drinkers returning to controlled drinking.
In 1976, a major study commonly referred to as the RAND report, published evidence of problem drinkers learning to consume alcohol in moderation. The publication of the study renewed controversy over how people with a disease which reputedly leads to uncontrollable drinking could manage to drink controllably. Subsequent studies also reported evidence of return to controlled drinking. Similarly, according to a 2002 National Institute on Alcohol Abuse and Alcoholism (NIAAA) study, about one of every six (18%) of alcohol dependent adults in the U.S. whose dependence began over one year previously had become "low-risk drinkers" (less than fourteen drinks per week and five drinks per day for men, or less than seven per week and four per day for women). This modern longitudinal study surveyed more than 43,000 individuals representative of the U.S. adult population, rather than focusing solely on those seeking or receiving treatment for alcohol dependence. "Twenty years after onset of alcohol dependence, about three-fourths of individuals are in full recovery; more than half of those who have fully recovered drink at low-risk levels without symptoms of alcohol dependence."
However, many researchers have debated the results of the smaller studies. A 1994 followup of the original seven cases studied by Davies suggested that he "had been substantially misled, and the paradox exists that a widely influential paper which did much to stimulate new thinking was based on faulty data." The most recent study, a long-term (60 year) follow-up of two groups of alcoholic men by George Vaillant at Harvard Medical School concluded that "return to controlled drinking rarely persisted for much more than a decade without relapse or evolution into abstinence." Vaillant also noted that "return-to-controlled drinking, as reported in short-term studies, is often a mirage."
The second RAND study, in 1980, found that alcohol dependence represents a factor of central importance in the process of relapse. Among people with low dependence levels at admission, the risk of relapse appears relatively low for those who later drank without problems. But the greater the initial level of dependence, the higher the likelihood of relapse for nonproblem drinkers. The second RAND study findings have been strengthened by subsequent research by Dawson "et al." in 2005 which found that severity was associated positively with the likelihood of abstinent recovery and associated negatively with the likelihood of non-abstinent recovery or controlled drinking. Other factors such as a significant period of abstinence or changes in life circumstances were also identified as strong influences for success in a book on Controlled Drinking published in 1981.
Managed drinking.
As part of a harm reduction strategy, provision of small amounts of alcoholic beverages to homeless alcoholics at homeless shelters in Toronto and Ottawa reduced government costs and improved health outcomes.
Legal considerations.
In 1988, the US Supreme Court upheld a regulation whereby the Veterans' Administration was able to avoid paying benefits by presuming that primary alcoholism is always the result of the veteran's "own willful misconduct." The majority opinion written by Justice Byron R. White echoed the District of Columbia Circuit's finding that there exists "a substantial body of medical literature that even contests the proposition that alcoholism is a disease, much less that it is a disease for which the victim bears no responsibility". He also wrote: "Indeed, even among many who consider alcoholism a 'disease' to which its victims are genetically predisposed, the consumption of alcohol is not regarded as wholly involuntary." However, the majority opinion stated in conclusion that "this litigation does not require the Court to decide whether alcoholism is a disease whose course its victims cannot control. It is not our role to resolve this medical issue on which the authorities remain sharply divided." The dissenting opinion noted that "despite much comment in the popular press, these cases are not concerned with whether alcoholism, simplistically, is or is not a 'disease.'"
The American Bar Association "affirms the principle that dependence on alcohol or other drugs is a disease."
Current acceptance.
Alcoholism is a disease with a known pathology and an established biomolecular signal transduction pathway which culminates in ΔFosB overexpression within the D1-type medium spiny neurons of the nucleus accumbens; when this overexpression occurs, ΔFosB induces the addictive state.
In 2004, the World Health Organization published a detailed report on alcohol and other psychoactive substances entitled "Neuroscience