FRIDAY, June 26 (HealthDay News) — A direct link exists between smoking and brain damage, researchers say.

The scientists found that a compound in tobacco triggers white blood cells in the central nervous system to attack healthy cells, resulting in severe neurological damage.

The compound, NNK, is a procarcinogen, which means it becomes cancer-causing when it’s altered by the metabolic processes of the body, the researchers wrote. NNK doesn’t cause direct harm to brain cells, but appears to cause neuroinflammation that leads to disorders such as multiple sclerosis.

Scientists at the National Brain Research Center in India found that NNK increases stress-related proteins such as pro-inflammatory signaling proteins and pro-inflammatory effector proteins, as well as pro-inflammatory cytokines, which act as molecular messengers between cells.

This demonstrates that NNK triggers an exaggerated response from the brain’s immune cells, called microglia. Normally, microglia cells attack damaged or unhealthy cells, but when provoked by NNK, they attack healthy brain cells, the researchers added.

“Our findings prove that tobacco compound NNK can activate microglia significantly, which subsequently harms the nerve cells,” lead researcher Dr. Anirban Basu said in a news release.

The study appears in the July issue of the Journal of Neurochemistry.

Since NNK is present in all tobacco products, it can also enter the body by chewing, the researchers noted. Secondhand smoke also contains high levels of NNK and can have a harmful effect on the brain, they said.

More information

The U.S. Centers for Disease Control and Prevention has more about the health effects of smoking.

— Robert Preidt

SOURCE: Journal of Neurochemistry, news release, June 23, 2009

Last Updated: June 26, 2009

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