People can increase blood flow to the brain by quitting cigarette smoking, even if they have smoked for 30 years or more, a new study concludes.

"Evidence suggests that nicotine and possible other constituents of cigarette smoke promote arterial vasoconstriction," or narrowing of arteries, reports Robert L. Rogers in the current Journal of the American Medical Association.

Rogers and other researchers at the Baylor College of Medicine in Houston studied 268 volunteers with an average age of 60 -- some nonsmokers, some smokers, and some who had quit.

Those who had never smoked had the best blood flow to the brain, measured by tracing tiny particles of xenon the subjects inhaled.

Those who quit smoking had uniformly better blood flow than those who continued to smoke, the study found.

This is one of several smoking studies reported in the current journal, which is largely devoted to the dangers of smoking.

"Elderly individuals who have smoked for three or four decades can benefit substantially by abstaining from cigarettes," the researchers conclude.

Meanwhile, the makers of a nicotine chewing gum estimate that the average man will -- in his lifetime -- save $17,590 in health care costs and lost work time by quitting smoking. Because women, as yet, don't smoke as heavily as men, the average woman will save $5,828, Merrell Dow Pharmaceuticals Inc. says.