Addiction to alcohol is a process that evolves over time, often years. Drinking to excess for an extended period of time increases the likelihood of developing a dependence on the drug. Mayo Clinic doctors report that for men, 15 drinks or more a week can lead to a physical dependence, while women drinking 12 or more drinks per week are at risk for becoming alcoholics. Time frames vary between individuals and can be affected by heredity, the age when the drinking first began, environmental factors, such as drinking in the home, and other emotional and mental disorders.