Dear A Moment of Science,

After more than 20 years of smoking, I'm trying to quit. But instead of feeling good, I'm feeling sad, even depressed. What's going on?

Smokin' Blues

It's normal for smokers to feel blue when they give up cigarettes. In fact, it's long been common to use antidepressants for smoking cessation.

When smokers quit, they go through withdrawal. And scientists have found that cigarette withdrawal often results in increased levels of a brain protein called monoamine oxidase-A, or MAO A a chemical related to mood that's elevated in people with clinical depression. Using brain imaging technology, the scientists discovered that the protein rose by twenty-five percent in the brains of heavy smokers within eight hours after they quit. Those same smokers also reported greater feelings of sadness, compared to a control group of non smokers.

Sadness And Depression

MAO A can lead to sadness and depression because it gobbles up other brain chemicals that help maintain a normal mood, such as serotonin. When there's too much MAO A in the brain, serotonin levels can drop to the point that a darker mood takes over.

For smokers trying to kick the habit, depression is a problem because it can make quitting that much harder. The study is helpful because it may lead to ways to help lower levels of MAO A, and to ward off the sadness it causes...

Which could make quitting smoking a little bit easier.