SUNDAY, Nov. 14 (HealthDay News) -- The Twin Cities of Minneapolis and St. Paul saw a sharp decline in the number of adult smokers over the last three decades, perhaps mirroring trends elsewhere in the United States, experts say.

The decline was due not only to more quitters, but fewer people choosing to smoke in the first place, according to research presented Sunday at the annual meeting of the American Heart Association (AHA), in Chicago.

"The magnitude of the decrease was a little larger than expected but the bigger surprise was that, among those people who continued to smoke, they decreased their cigarette consumption," said study lead author Kristian Filion, a postdoctoral associate in the division of epidemiology and community health at the University of Minnesota School of Public Health in Minneapolis.

The likely reasons for the downturn? Filion believes it's attributable to legislation and to specific programs funded by tobacco-settlement funds, plus the sheer cost of cigarettes today.

One expert said the findings reflected trends he's noticed in New York City.

"I don't see that many people who smoke these days. Over the last couple of decades the tremendous emphasis on the dangers of smoking has gradually permeated our society and while there are certainly people who continue to smoke and have been smoking for years and begin now, for a variety of reasons I think that smoking is decreasing," said Dr. Jeffrey S. Borer, chairman of the department of medicine and of cardiovascular medicine at the State University of New York (SUNY) Downstate Medical Center. "If the Minnesota data is showing a decline, that's probably a microcosm of what's happening elsewhere."

The findings come after U.S. regulators on Thursday unveiled proposals to add graphic images and more strident anti-smoking messages on cigarette packages to try to shock people into staying away from cigarettes.

The authors of the new study, from the University of Minnesota, Minneapolis, canvassed residents of the Twin Cities on their smoking habits six different times, from 1980 to 2009. Each time, 3,000 to 6,000 people participated.

About 72 percent of adults aged 25 to 74 reported ever having smoked a cigarette in 1980, but by 2009 that number had fallen to just over 44 percent among men. For women, the number who had ever smoked fell from just under 55 percent in 1980 to 39.6 percent 30 years later.

The proportion of current male smokers was cut roughly in half, declining from just under 33 percent in 1980 to 15.5 percent in 2009. For women, the drop was even more striking, from about 33 percent in 1980 to just over 12 percent currently.

Smokers are consuming fewer cigarettes per day now, as well, the study found. Overall, men cut down to 13.5 cigarettes a day in 2009 from 23.5 (a little more than a pack) in 1980 and there was a similar trend in women, the authors reported.

But one expert warned that for smokers who don't quit but just cut down, risk remains.

"It is good news that there has been a drop in smoking rates over the last decades, but the public needs to be aware that 'cutting down' to even a few cigarettes per day can [still] triple that person's risk of heart disease," said Dr. Len Horovitz, a pulmonary specialist with Lenox Hill Hospital in New York City. "Any smoking on the part of asthmatics will increase asthma attack rates and, of course, second-hand smoke is a known cause of asthma in children."

According to the new study, men started smoking, on average, just before their 18th birthday throughout the three decades. However, there was a disturbing trend towards a younger start for smoking among females: women began puffing at about 19 years of age in 1980 and around 18 in 2009, the study found.

Rates of smoking started lower and decreased more in men who had gone on to college after high school, from 29 percent in 1980 to 11 percent in 2009. Among those who didn't finish high school or only completed high school, the decline was 42 percent to 31 percent.

Other research presented at the AHA meeting found that quitting smoking does not completely erase the risk of heart failure, even among people who smoked their last cigarette 15 years ago.

This contradicts a 2004 report from the U.S. Surgeon General that indicated that the risk of heart failure drops among former smokers to that of never-smokers after 15 years.

Twenty percent of people who had never smoked developed heart failure over the 12 years that researchers followed them, compared with 29 percent among heavy smokers who had managed to quit. Former smokers also had a higher risk of having a heart attack or dying during the follow-up period.

The good news is that the risk of heart failure did drop the longer a person abstained from cigarettes, said the researchers at the University of Alabama, Birmingham.

Although quitting smoking may not eliminate the risk of heart failure, it does improve one risk factor for heart disease, a third study presented at the meeting found.

People who had given up the habit gained higher blood levels of high-density lipoprotein (HDL or "good") cholesterol -- even though they gained an average of 10 pounds (versus 1.5 pounds in those who didn't quit).

Ceasing smoking did not affect levels of "bad" low density lipoprotein (LDL) cholesterol levels, however, researchers at the University of Wisconsin, Madison found.

More information

There's more on smoking and its effects on the heart at the American Heart Association.