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American lives have been getting steadily longer. And since the 1960s, that trend has been driven mostly by a remarkable reduction in heart disease. But those improvements have slowed dramatically, and scientists are now wondering whether we're approaching the end of this trend of longer, healthier lives. NPR's Richard Harris looks at what is driving this change.
RICHARD HARRIS, BYLINE: Most people alive today don't remember the days when people in their 40s and 50s would simply drop dead of a heart attack. But 79-year-old Ken Carbaugh certainly does.
KEN CARBAUGH: When I was a kid a long time ago, I remember an awful lot of people died from indigestion. They - that's what they said it was, but that's not what it was. They were having heart attacks, and they didn't even know it.
HARRIS: Carbaugh has lived through a remarkable period of history. During his lifetime, cardiovascular disease dropped dramatically as a cause of death, from killing about half of all Americans back in the 1960s to only about one-quarter today. These days, it's not unusual to find someone like Carbaugh - nearly 80 years old, hale and hearty.
CARBAUGH: I think I'm better than average for my age. I'm really - at least when I was younger and I looked at older people, they didn't look as good as I am now, I don't think (laughter).
HARRIS: Carbaugh has helped tell that success story himself. For the past 30 years, he's volunteered in a study to track heart health in the United States. On this day, he's driven in from his home on a country road to Hagerstown, Md., where he's getting a periodic exam.
MELISSA MENOTTI: If you want to start to this side - OK. I need your toes right up against the red line, but not touching.
HARRIS: Melissa Menotti manages this project at an outpost of Johns Hopkins University. The low-slung building is right next to Antietam Creek, about 10 miles upstream from the Civil War battlefield. She's going to measure how far Carbaugh can walk in two minutes up and down a carpeted hallway.
MENOTTI: All right. You ready?
MENOTTI: Three, two, one - go.
HARRIS: This is just one of a battery of tests which will take five hours for Carbaugh to complete. He's one of about 4,000 people here in Washington County, Md., recruited in the 1980s for this long-term study. The youngest is now 75, and more than half are still alive. Dr. Joe Coresh from Hopkins says this is one of four counties that has been providing a very detailed look at heart health for a federally funded study called ARIC.
JOSEF CORESH: So over the last 30 years, we've been following the 16,000 people from the late '80s until now. And they've been kind enough to volunteer for examinations and phone calls twice a year. And that means that they've contributed, really, sort of invaluable data that will stick around forever. So ARIC, like the Framingham Heart Study, have become sort of national resources and treasures for research.
HARRIS: The point of this study isn't really to track the national trends in heart disease and stroke but to understand, on a very personal level, what's behind them.
CORESH: Of the decline in heart attacks, about half is due to a management of risk factors, and about half is due to improved medical care.
HARRIS: People stopped smoking. They started taking drugs to control blood pressure and cholesterol. Surgeons reopened arteries, and hospitals built cardiac care units. So why is the trend in improving heart health leveling out? Partly because the easier stuff has been done. Donald Lloyd-Jones at Northwestern University says that's not all.
DONALD LLOYD-JONES: The greater cause of the stagnation in cardiovascular disease death rates is that the obesity epidemic, which started in this country in about 1985, is finally coming home to roost.
HARRIS: Obesity raises blood pressure, cholesterol levels and the risk of diabetes.
LLOYD-JONES: All the things that put us at risk for heart disease and stroke get much, much worse.
HARRIS: And considering the burden of obesity in this country now, by 2030, heart disease could not just increase but it could cost a whopping $800 billion a year. Dr. Lloyd-Jones says. That's equivalent to the stimulus package that Congress passed in 2008 to prevent a global financial disaster.
LLOYD-JONES: That was a hard lift for our political system. By 2030, you know, the American Heart Association is projecting that we'll have to pass that bill every single year just to pay for cardiovascular diseases.
HARRIS: This is not just a potential financial disaster. It could also be a blow to the expectation that our collective health will just keep on getting better. David Jones, a medical historian at Harvard, says that idea was first challenge when the former Soviet Union collapsed. When that happened, life expectancy fell by five years. AIDS in sub-Saharan Africa led to an even worse decline.
DAVID JONES: And those two warning signs really burst the bubble that people had had about this expectation of inevitable progress. And people realized that the great gains we had made over the 20th century were potentially vulnerable as certain things went wrong.
HARRIS: Obesity is a slow-moving epidemic, so it may not result in a rapid rise in deaths. And even with the burden of obesity, Dr. Jones says it still might be possible to reduce heart disease rates further by eliminating smoking and controlling blood pressure and cholesterol.
JONES: The question of what we would die of in the absence of heart disease is one of these million-dollar questions. I think - and this is one of these things that people been puzzling about for a long time.
HARRIS: That question is starting to come into focus at the medical building in Washington County, Md. As the study group has grown older, the research has evolved to address their ongoing health challenges and to look at the risks that now loom for this generation.
LILY PINKHAM: All right. This next task will involve repeating sentences that you will hear with varying levels of background noise. Imagine...
HARRIS: Technician Lily Pinkham sits at a computer terminal outside a soundproof booth. Inside, 79-year-old Pat Reeker gamely tries to pick out the sentence from the noise.
PAT REEKER: A gold vase is both - something and costly.
HARRIS: After the soundproof booth opens, she says she's learned her lesson.
REEKER: Stay away from chainsaws and loud lawnmowers, right?
HARRIS: Hearing tests here are part of an effort to understand the next potential epidemic in this country, dementia. Memory loss can be hastened by failing hearing. It can be caused by degenerating nerves, as is the case in Alzheimer's. And it can also be triggered by what causes heart disease, clogged and hardened arteries. Dr. Coresh says some dementia is probably amenable to prevention if research projects like his can pin down the risk factors.
CORESH: But it's going to need decades of prevention, so we need to probably have risk factors treated in middle age to prevent disease in older age.
HARRIS: If medical science can indeed hold the line on heart disease, it would be disheartening if that simply meant people died of dementia instead.
Richard Harris, NPR News.
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