If the best part of waking up is coffee in your cup, chances are you're dependent on your morning brew -- and so is your family.
The jolt you get from drinking java or soda may seem small, but caffeinated drinks "can be addictive," says Kenneth Kendler, M.D. The news may be surprising to some, but likely makes sense to the many Americans who can't face the day without hitting Starbucks first.
"Caffeine likely performs like other psychoactive substances of abuse," he warns. And like its more hard-hitting counterparts, alcohol, cigarettes and drugs, its ill effects seem to depend partly on your genes.
Kendler, a professor of psychiatry at Virginia Commonwealth University Medical College, examined 1,000 sets of female twins to see if caffeine use ran in the family. He looked at several markers of caffeine addiction: whether the women used tea, soda or coffee heavily (did they drink 625 mg of caffeine, equivalent to five cups of coffee, a day?), how tolerant they were to it (did they find themselves needing to drink more than their usual amount to get a buzz?), and whether they experienced withdrawal (headaches, depression or nausea) when they stopped drinking the beverages.
