Scientists at the Brudnick Neurophsyciatric Research Institute at the University of Massachusetts Medical School have pinpointed specific areas in the brain that could be responsible for nicotine withdrawal symptoms like nausea, headaches, irritability and weight gain that make it so difficult to go cold turkey.
About 69 percent of smokers say they want to quit smoking, but nicotine, the drug in tobacco products, may be as addictive as heroin and cocaine, according to the U.S. Centers for Disease Control.
“We’re trying to understand what chronic nicotine [use] does for the brain that makes it hard to quit,” said Andrew Tapper, PhD, a neuroscientist at UMass and co-author of the new study.
Kennerley is a case in point. “I’d smoke one or two [cigarettes] and then throw them away and be mad at myself,” he said. “[Smoking], that’s all I could think about. It’s such a strong craving.”
Why Is It so Tough to Quit?
In an effort to understand nicotine addiction, Dr. Tapper’s team gave mice nicotine-laden water for six weeks until their brains, much like human brains, were hooked on the chemical. Then they took the nicotine water away and watched as the mice went through their own version of withdrawals: excessive grooming, scratching, digging and shaking. The researchers looked at the mice brains and found activity within the interpeduncular nucleus, an area deep under the cortex in the middle of the brain.
“We found that when you get an animal dependent on nicotine and you take it away, this little brain region became overactive,” said Tapper.
The nicotine in cigarettes is a highly addictive chemical because when you smoke a cigarette, the nicotine travels to your brain and attaches itself to a nicotinic receptor. Those receptors then release a chemical called dopamine, which is also released after other fun things, like having sex or eating cupcakes. Dopamine makes you feel good, and your brain associates those good feelings with smoking.
Quitting is challenging because the brain becomes accustomed to constant doses of nicotine. If you stop smoking, the drug leaves your system, and neurons in the interpeduncular nucleus trigger withdrawal symptoms — irritability, anxiety, difficulty concentrating and weight gain — that might prompt you to smoke again.
“Even though you tell yourself, ‘No, no, no,’ your brain will find a way to convince you [smoking] is a good idea,” said Kennerley, who finally gave up cigarettes in 2009 after many attempts. “It feels like your brain is tricking you. It will convince you against better judgment that [smoking] is what you want.”
Smoking Addiction Kills
When Tapper activated neurons in the interpeduncular nucleus region in mice who weren’t addicted to nicotine, they, too, started exhibiting withdrawal symptoms. This suggests that there’s a strong connection between the this area of the brain and the negative side effects of nicotine detox.
If scientists could figure out how to placate these neurons and get rid of those withdrawal symptoms, more people might give up the habit, they theorize.
“[This research] is important for people who have a very hard time quitting,” said John Dani, PhD, a neuroscientist and nicotine addiction expert at the University of Pennsylvania School of Medicine. “I’ve seen people standing outside in their hospital gowns smoking a cigarette — they just can’t quit.”
Tobacco use costs the U.S. $97 billion in lost productivity, and contributes to 5 million deaths worldwide every year. Statistics show that smokers die more than 10 years earlier than non-smokers.
“Adverse health consequences of smoking make it the most preventable cause of mortality in the world, and that’s why we’re working on it,” Tapper explained.
Tapper’s research is still preliminary and was conducted only in mice, but it seems to be a meaningful step forward that could provide targets for stop-smoking drug development, said Dr. Dani.
“This circuitry is working in a way that’s helping to perpetuate [smoking]. The brain has been tricked into thinking [smoking] is valuable, and that’s how addiction starts,” Dani said. “The better we understand how these circuits shape behavior, the more likely we are to be able to control them.”