For smokers, the smell and feel of a cigarette can be even more tempting than the nicotine itself. In studies at Duke University, smokers preferred to inhale a nearly nicotine-free cigarette than to take a hit of nicotine through an IV. That helps explain why nicotine-replacement therapy yields long-term quit rates below 20 percent, says Jed E. Rose, a psychiatry professor at Duke. He found that dissociating sensory cues from nicotine—by giving smokers a nicotine patch and denicotinized cigarettes for two weeks—doubles the rate of quitting relative to the patch alone. In general, Rose advises treating both the physical and psychological aspects of addiction, for example, with nicotine replacement and counseling.