TUESDAY, May 6 (HealthDay News) -- New research shows that women who quit smoking have a 47 percent lower risk of dying from coronary heart disease within five years of extinguishing their last cigarette.

The risks of dying from other conditions also decline after quitting, although the time frame varies depending on the disease.

"The harms of smoking are reversible and can decline to the level of nonsmokers," said study author Stacey Kenfield, whose report is in the May 7 issue of the Journal of the American Medical Association. "For some conditions like chronic obstructive pulmonary disease, it can take more than 20 years, but there is a rapid reduction for others."

"It's never too early to stop, and it's never too late to stop," added Kenfield, who is a postdoctoral research fellow in the department of epidemiology at the Harvard School of Public Health in Boston.

Smoking is still the leading preventable cause of death in the United States. Not only does tobacco smoke cause lung cancer, it is also implicated in heart disease, other cancers and respiratory diseases.

According to the World Health Organization, an estimated 3 million people in industrialized countries will have died as a result of tobacco use by 2030, and an additional 7 million people in developing countries face the same fate.

This research is a continued follow-up on the Nurses' Health Study, a large trial involving more than 100,000 women. Scientists now have 22 years of data on the participants.

Current smokers had almost triple the risk of overall death compared with women who had never smoked.

Current smokers also had a 63 percent increased risk for colon cancer compared with never-smokers, while former smokers had a 23 percent increased risk. There was no significant association between smoking and ovarian cancer.

And women who started smoking earlier in life were at a higher risk for overall mortality, of dying from respiratory disease and from any smoking-related disease.

However, a smoker's overall risk of dying returned to the level of a never-smoker 20 years after quitting. The overall risk declined 13 percent within the first five years of abstaining.

Most of the excess risk of dying from coronary heart disease vanished within five years of quitting.

For chronic obstructive pulmonary disease, the return to normal took more than 20 years, although there was a 13 percent reduction in the risk of death seen within five to 10 years after quitting.

And the risk for lung cancer didn't return to normal for 30 years after quitting, although there was a 21 percent reduction in risk within the first five years compared with women who continued to smoke.

Many previous studies on tobacco use had focused on men and on lung cancer, the authors stated. They also only looked at smoking status at the beginning of the study. "We got smoking information every two years, so we feel we have a more accurate estimate of current and past smoking," Kenfield said. "We saw increased risks for current smokers [than previous studies], and we think that's because we know who the current smokers are."

"This shows the power of quitting smoking," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "We've known this for a number of years, but the beauty of this study is it is a very large and well-studied group of people. When I tell people to quit smoking, I say the effect of the heart precedes that of the lungs. If you've smoked, you need to be cognizant that you're still at an increased risk of lung cancer."

More information

Visit the American Lung Association for more on women and smoking.

The finding helps explain the increased risk of such cardiovascular problems found in previous studies of marijuana, said Dr. Jean Lud Cadet, chief of the Molecular Neuropsychiatry Research Branch of the National Institute of Drug Abuse. He is lead author of the report, published in the May 13 issue of Molecular Psychiatry.

"We've done a number of clinical papers reporting on marijuana users," Cadet said. "In the past, we have reported cognitive abnormalities, and a paper in 2005 reported vascular [blood vessel] abnormalities."

The latest paper looked at blood levels of a variety of proteins in 18 long-term heavy users of marijuana and 24 volunteers who had never used the drug. It used a new electronic technology that made such protein measurements possible, Cadet said.

"The idea was that there might be marijuana-induced changes in proteins related not only to the vascular problems we were reporting but also to other medical problems marijuana users suffer from," he said.

The analysis showed significantly higher blood levels of apolipoprotein C-III in the marijuana users than in the nonusers. APOC-III is one of a large family of proteins that interact with fats. It delays the breakdown of triglycerides, fats that can accumulate in blood vessels and promote formation of plaques, leading to blockages that can cause heart attacks, strokes and other problems.

"It is a risk factor for cardiovascular disease," Cadet said. "The study suggests that APOC-III might be one of the risk factors contributing to the medical problems that marijuana users suffer from."

In terms of heart disease and stroke, is smoking marijuana more dangerous than smoking tobacco? "It is very difficult on the basis of our study to say," Cadet said, since there was no comparison between marijuana and tobacco smokers.

"It is an interesting study, but I don't think it is particularly profound," said Dr. Christopher Granger, a professor of medicine at Duke University who has done studies of risk factors in cardiovascular disease. "It looks at a relatively small number of people and the relationship between marijuana and this particular protein in the blood stream. There is a relationship, but there is far from proof that it is cause-and-effect, and if it is cause-and-effect that it would have an effect on the people using marijuana."

The study "does lift us to a new level of understanding about marijuana use, that it may have a real impact on the way people who use marijuana metabolize food, showing that it could have an adverse effect on cholesterol," Granger said.

"I consider this study exploratory, by definition, because of the technique they used, sort of a shotgun approach," said Dr. Kenneth Mukamal, an associate professor of medicine at Harvard Medical School who has studied the effects of marijuana use on cardiovascular disease. "They chose this protein out of a range of thousands of possibilities, so there is a chance you find something just by luck."

The effects of marijuana on the cardiovascular system are still uncertain, Mukamal said. "It has negative effects on heart rate and may even trigger heart attacks," he said. "But in mice, it apparently prevents atherosclerosis. Whether it is good or bad remains a question."

More information

The medical pros and cons of marijuana are described by the National Institute on Drug Abuse.

TUESDAY, May 13 (HealthDay News) -- Patients who received the blood pressure-lowering drugs known as beta blockers after having non-cardiac surgery were at higher risk of dying or having a stroke, a new Canadian study found.

However, the patients receiving the medications were less likely to have a heart attack, according to the report in the May 13 online issue of The Lancet.

"For a decade now there are guidelines saying you should give beta blockers to people having non-cardiac surgery," said lead researcher Dr. P.J. Devereaux, an assistant professor in the Department of Clinical Epidemiology and Biostatistics at McMaster University in Hamilton, Ontario.

The reason for giving beta blockers is that surgery increases the heart's need for oxygen and beta blockers help reduce blood pressure and heart rate, reducing strain on the heart, Devereaux explained.

Around the world, an estimated 100 million people have major non-cardiac surgery each year, so the finding could have serious consequences for many patients, Devereaux noted.

"In the last decade, even if only 10 percent of patients undergoing non-cardiac surgery were given beta blockers, that means 100 million people were given beta blockers, and that means 800,000 people died unnecessarily and a lot of people suffered a major stroke because they were given a beta blocker," Devereaux said.

In the study, 8,351 patients at 190 hospitals across 23 countries who were at risk for atherosclerotic disease [hardening of the arteries] and undergoing non-cardiac surgery were randomly selected to receive a beta blocker or a placebo. The beta blocker was given two to four hours before surgery, and continued for 30 days after the procedure.

The researchers found that patients receiving beta blockers were 16 percent less likely to have died from heart disease, compared with those receiving a placebo. In addition, those taking a beta blocker were 27 percent less likely to have a heart attack than patients receiving a placebo.

But, more people taking a beta blocker died than those taking a placebo. In fact, patients taking a beta blocker had a 33 percent increased risk of dying compared with patients taking a placebo.

Also, there were more strokes among people taking a beta blocker than among patients receiving a placebo. Those receiving the beta blocker had double the risk of suffering a stroke compared with patients receiving a placebo, the researchers reported.

The most likely explanation for the increase in deaths and stroke among those taking beta blockers was that these patients could go into shock if their blood pressure were too low, a not uncommon complication of surgery, Devereaux said. "If they were on the beta blockers they were in big trouble, and [it] increased their likelihood of dying or suffering a stroke," he said.

Devereaux doesn't think reducing the risk of heart attack is worth increasing the risk of stroke or death. "I don't think most patients would be willing to accept the excess death and excess stroke for preventing a heart attack," he said.

Using a beta blocker to prevent heart attacks in these patients is not the right strategy, Devereaux said. "If we are causing so much harm to prevent heart attacks, we need to find another solution which will prevent these events, but not have the same risk."

One expert thinks that the doses of beta blockers given in the trial were too high.

"The increase in hypotension [low blood pressure] and resulting strokes and cardiovascular deaths may be a result of this overly aggressive dosing rather than perioperative beta blocker therapy in general," said Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles.

"While further studies of other beta blockers and dosing regimens for perioperative use are still needed, the rapid up-titration to high dose of a beta blocker regimen employed in this study should be avoided," Fonarow said.

Another expert thinks that if beta blockers are given cautiously, the dangers found in the study can be greatly reduced.

"We don't want people to misinterpret this study," said Dr. Lee A. Fleisher, chair of the Department of Anesthesiology and Critical Care at the University of Pennsylvania School of Medicine, and author of an accompanying editorial in the journal. "The study did not say anybody who is on beta blockers should stop them."

Fleisher agrees that starting beta blockers the morning of surgery with high doses is not a good way to go. "That type of protocol is not good," he said.

More information

For more on beta blockers, visit the American Academy of Family Physicians.

MONDAY, May 12 (HealthDay News) -- Long-term exposure to the tiny, dirty particles in polluted air seems to increase the risk of deep vein thrombosis, which are blood clots in the thighs or legs, an Italian study finds.

"It is well-established that air pollution causes myocardial infarction [heart attack] and stroke," said Dr. Andrea Baccarelli, who led the study while at the Harvard School of Public Health. "This is the first time that anyone has connected air pollution with deep vein thrombosis."

Previous studies have suggested such a connection, said Baccarelli, who is now an assistant professor of environmental health at the University of Milan. "Several studies in animal models and in humans have shown that particulate matter, inhaled into the lungs, causes inflammation in the lungs," he said. "The inflammation can expand the cell body, so that the incidence of coagulation is increased."

Coagulation is the formation of clots that can block blood vessels.

Baccarelli and his colleagues assessed the effect of air polluted with particulate matter smaller than 10 micrometers in diameter -- about one-40th the width of a human hair. Such particles come from the exhaust of vehicles, especially those with diesel engines, and burning of fossil fuels, the researchers said.

The scientists compared the exposure to such pollution on 870 residents of the Lombardy region of Italy who had been diagnosed with deep vein thrombosis, and 1,210 residents who did not have deep vein thrombosis. The researchers used the average concentration of particulate matter measured by monitors at 53 sites.

Compensating for other environmental and health factors, the researchers found that the risk of deep vein thrombosis increased by 70 percent for every increase in particulate matter of 10 micrograms per square meter. Tests showed that the blood of people more exposed to such pollution took less time to form clots.

"This makes a very strong case that air pollution is connected to deep vein thrombosis," said Dr. Robert D. Brook, an assistant professor of internal medicine at the University of Michigan, who wrote an accompanying editorial in the journal.

"But it is a first study and a single study," he added, "and I would be cautious about making generalizations and drawing conclusions on the basis of one study."

Still, "the results are very positive," Brook said. "Even if they are overestimating the effect, the effect, which is relatively so robust, is there. But how strong it is requires further studies."

"If future studies corroborate their findings and address some of the limitations, it may be proven that the actual totality of the health burden posed by air pollution, already known to be tremendous, may be even greater than anticipated," Brook said.

Baccarelli agreed with Brook's assessment, saying, "clearly the finding needs to be confirmed in additional studies."

"We are working on that," he said. "We are seeking additional populations in which the same link between air pollution and deep vein thrombosis can be evaluated. We also hope that some of our colleagues elsewhere will be pushed to conduct other studies."

The findings are published in the May 12 issue of the Archives of Internal Medicine.

More information

Learn more about the health risks of air pollution from the U.S. National Library of Medicine.

The simple truth, experts say, is that pounds must also be shed to keep cardiovascular trouble away.

"There is a debate out there about whether this generation is going to live as long as their parents, and the truth is they probably won't," said study author Dr. Gregory L. Burke, director of the division of public health sciences at Wake Forest University School of medicine in Winston-Salem, NC.

"My ultimate worry is that we've seen a 50-year decline in cardiovascular disease mortality, but if you begin to look at recent trends, it's beginning to plateau," he added. "And my fear is that because of the increase in obesity we're going to begin to see a reversal of that trend where heart disease rates begin to go up."

The research involving 6,814 men and women aged 45 to 84 revealed an even greater prevalence of overweight and obesity than shown in similar studies done five years earlier. Depending on the demographic group, between 60 percent and 85 percent of the participants were overweight and between 30 percent and 50 percent were obese, the federally funded study found. The obesity epidemic is more likely environmentally than genetically driven, Burke said. The differences between the weights of white, black and Hispanic Americans are no longer as meaningful, he stressed. Only Chinese-Americans have significantly less obesity (5 percent) than other ethnic groups.

A decade ago, experts thought the heart-related risks of obesity could be counterbalanced by the treatment of risk factors such as high cholesterol and glucose intolerance, Burke explained. People thought that, "Gosh, all we need to do is treat those risk factors and we can ameliorate the effects of obesity. So, our study looked at whether that is indeed true," he added.

It isn't, said Burke, noting that this is where his study breaks new ground. There is a relationship between less obvious, subclinical cardiovascular disease markers, such as the thickening of the walls of the carotid artery, and obesity, he explained. Even though the overweight and obese people studied hadn't had heart attacks they did show various markers that are predictors of future cardiovascular events, Burke added. This is was true despite the high number of people who were taking medications for the well-known triad of risk factors of high cholesterol, diabetes and high blood pressure.

Lona Sandon, a spokeswoman for the American Dietetic Association, said that the findings show that "many of the people who were obese were being treated with various medications, but they still were not improving to the point where they were decreasing their risk."

The American mentality is that "if I just take those pills, I'll be OK," said Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical School. The study "kind of says you have to make some changes, some lifestyle changes and some food changes, to lead to a healthier weight."

Sandon added that even greater emphasis needs to be placed on prevention. "It's easier to prevent with an hour of exercise a day than correct with three hours of exercise a day," she noted. "Hopefully [the study] can be some kind of a wake-up call to tell us we need to do something more than hand out a prescription."

More information

For more on fighting obesity, go to the Obesity Action Coalition.