from Wickipaedia:
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. The American Medical Association (AMA) had 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.
Alcoholism is a chronic problem. However, if managed properly, damage to the brain can be stopped and to some extent reversed. [[1]](http://en.wikipedia.org/wiki/Alcoholism_%28disease%29#cite_note-1) In addition to problem drinking, the disease is characterized by symptoms including an impaired control over alcohol, compulsive thoughts about alcohol, and distorted thinking . [[2]](http://en.wikipedia.org/wiki/Alcoholism_%28disease%29#cite_note-MORSE1992-2) 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; [citation needed ] however, many individuals have developed alcoholism without a family history of the disease. [citation needed ] 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. [[3]](http://en.wikipedia.org/wiki/Alcoholism_%28disease%29#cite_note-The_Genetics_of_Alcohol_Dependency-3)
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.