Research on the physical aspects of addiction has helped scientists make progress on developing drugs to block cravings, Time magazine reported.
The research has led to greater knowledge of how "deeply and completely" addiction can affect the brain, and as a result new drugs are being designed to help block cravings that can lead to a relapse, the magazine said.
An estimated 18.7 million Americans -- 7.7 percent of the population -- depend on or abuse alcohol, Time said. An estimated 3.6 million people are dependent on drugs, while 700,000 are undergoing treatment for drug addiction.
About 71.5 million people use tobacco products. Almost 25 percent of men and 20 percent of women are cigarette smokers.
Time also pointed out that between 80 percent and 90 percent of Americans ingest caffeine, mainly in coffee and soda, and up to 4 million adults are addicted to food. Food addiction has been linked to depression.
In addition, 2 million Americans are thought to be pathological gamblers and another 4 million to 8 million are considered problem gamblers.
Copyright 2007 by United Press International
Explore further: World's poorest children twice as likely to contract malaria as least poor