"A prune-size bit of tissue tucked under the frontal lobes, it controls gut feelings and habits; it's what drives a recovering smoker to yearn for the feel and taste of cigarettes. The "reward circuitry," a network of neurons at the core of the brain, also plays a role. Nicotine boosts the brain's levels of dopamine, the "feel good" neurotransmitter. Another, as yet unknown, chemical in tobacco smoke acts like an antidepressant, blocking an enzyme that breaks down dopamine. So smokers get a double dose of the stuff—and about half end up addicted, essentially, to their own brain chemicals.

Remove the nicotine, though, and the body can't maintain the high dopamine levels on its own. In the brain of a smoker who's trying to quit, receptors start "screaming," says Dr. Norman Edelman of the American Lung Association, "crying out to be satisfied." Smokers often say a cigarette calms them, but by the time they're addicted, the nicotine rush simply halts the first symptoms of withdrawal. "The addiction is why you're nervous in the first place," says Edelman. Longtime smokers also have to end a behavior that's "entrenched in their daily lives," says Corinne Husten, head of the CDC's Office of Smoking and Health. Add in the stresses of, say, running for president, and it's all too easy to slip.

It may seem drastic to call a smoker an "addict" but, says Chris Cartter, who runs QuitNet, the world's largest quit-smoking program, "a lot of doctors view this as on par with overcoming a heroin addiction." The withdrawal isn't as ugly, but it's not pretty, either: shortly after quitting, the typical longtime smoker becomes cranky, has trouble sleeping and making decisions, and gains weight. Usually, the first weeks are the worst, but for some people the symptoms can drag on for a year or more.

That's assuming, however, that the smoker is taking the cold-turkey approach, which there's little reason to do these days. Nicotine gum, approved in 1984, is the oldest anti-smoking aid. (Obama chews it throughout the day.) It's about as effective as the newer patches, inhalers and nasal sprays, all of which placate those screaming receptors without being addictive themselves. Other options include Zyban, which is also marketed as an antidepressant, and Chantix, introduced last year, which eases withdrawal and blocks nicotine's effects."

http://www.msnbc.msn.com/id/17193908/site/newsweek/

Expired in Queue - 4 day limit.