Alcohol dependence is the most severe type of drinking problem. There is no absolute number of drinks per day or quantity of alcohol that defines alcoholism, but experts have defined a limit above which the risks of drinking increase significantly. Here are some defining characteristics of alcohol dependence:
--Tolerance – The need to drink more and more alcohol to feel the same effects, or the ability to drink more than other people without getting drunk.
--Withdrawal symptoms – After stopping or cutting back on drinking, symptoms are anxiety, sweating, trembling, trouble sleeping, nausea or vomiting, and, in severe cases, physical seizures and hallucinations.
--Desire to stop drinking, but inability to do so.
--Loss of control over the amount of alcohol consumed.
--Preoccupation with drinking.
--Paying less attention to other life activities.
--Ignoring problems, sometimes very obvious ones.

A person with alcohol dependence has come to rely on alcohol physically, psychologically and emotionally. The brain adapts to the presence of alcohol and undergoes persistent changes. When alcohol use suddenly stops, the body's accustomed internal environment changes drastically, causing symptoms of withdrawal.