Everyone knows smoking can be addictive, but a new study suggests the threshold for addiction appears to be far lower in teens than it is in adults. According to researchers from the University of California at San Francisco, adults who smoke less than five cigarettes a day often are not technically considered addicts. “Most smoking cessation programs require that you smoke at least 10 cigarettes per day,” says Dr. Mark Rubinstein of UCSF; but when researchers examined the brain activity of teens who smoked fewer than five cigarettes daily, they found these teens registered the same levels of addiction as heavily smoking adults. (CounselHeal)