Multiple biological and psychosocial factors mutually influence each other in causing alcoholism. It usually develops slowly over a course of 5 to 15 years of heavy drinking. There are several factors that play a role in the disease such as chemical imbalances in the brain, heredity, cultural acceptance, and stress.
Any adult and most minors have access to alcohol. People celebrate with alcohol, drink at sporting events, parties, and at home with dinner. Social pressure, especially during college years, encourage people to drink in excess. Most people learn to control their alcohol intake, while others continue to abuse alcohol to the point of alcoholism.
While almost everyone is exposed to alcohol in some way or another, the immediate families and friends of alcoholics are exposed to alcohol much more in more detrimental ways.
Children of alcoholics have less sensitivity to the negative effects of alcohol, like body sway and intoxication. Fifty percent of those with alcoholism have at least one parent with alcoholism, and those with a family history have a more severe disease course than those without such a history.
It is estimated that 40-60% of the risk for developing any addiction, including alcoholism, is genetic. Studies with adoptees have shown that having a familial history of alcoholism increases both the risk of developing an alcohol dependancy and its severity. According to one study, having a familial history of alcoholism but being raised in a household without alcohol abusers still leads to a fivefold increase in the odds of becoming an alcoholic. However, environmental factors are still important - the same study found a ninefold increase in the odds of becoming an alcoholic given both a family history of alcoholism and an alcoholic foster-parent.
While there has been much attention given to identifying genes that cause a predisposition for alcoholism, a single "alcoholism gene" has yet to be discovered. While distributions of certain alleles of genes seem to be different in alcoholics and non-alcoholics, it is generally accepted that the heritable component of alcoholism is polygenetic, so no single gene is likely to account for more than a fraction of the risk of alcoholism.
Some genes, also, may only increase the risk of alcoholism when certain environmental factors are also present.
For example, the Taq1 polymorphism of the D2 Dopamine receptor is a risk factor for Alcoholism only when someone carrying this gene is also stressed. Genetics may also affect the extent of damage resulting from chronic alcohol use; studies have documented genetic predispositions for cancer of the esophagous, oropharyngolaryngeal cancer, and liver damage in alcoholics.