Smoking Lowers Key Brain Enzyme, Researchers Find

Smoking lowers the brain’s supply of an enzyme called monoamine oxidase B, a process that might heighten the addictive power of nicotine, according to a report in the Feb. 22 issue of Nature. If so, drugs now used to treat Parkinson’s disease might help people quit smoking, said researcher Joanna Fowler of the Brookhaven National Laboratory in Upton, N.Y.

The enzyme, MAO-B, is produced by brain cells and is involved in the natural destruction of the neurotransmitter dopamine. Heightened dopamine release may enhance nicotine addiction. The team used positron emission tomography to scan the brains of eight smokers, eight nonsmokers and four ex-smokers. They found that smokers had about 40% less of the enzyme than nonsmokers, which would increase levels of dopamine in the brain.