GWEN IFILL:And we close about with new findings about declining life spans for some women. Those come from a pair of new studies.

The first reported that, in 43 percent of the nation's counties, many of them in the South and the West, women—more women 75 and younger are dying sooner. The second study found mortality for all Americans under 50, but particularly women, is more pronounced in the U.S. than other high-income countries. Both were published in the journal "Health Affairs."

Editor in chief and a NewsHour regular Susan Dentzer joins me now.

Susan, hello.

SUSAN DENTZER, “Health Affairs”: Nice to be with you, Gwen.

GWEN IFILL:So, the first question is why. Why are we seeing these increased mortality rates at younger ages?

SUSAN DENTZER:This is an unfortunate stew of unpleasant circumstances.

Chronic disease is driving a lot of this early death in women. A lot of this is death before the age of 50, believe it or not. So it's issues like obesity, correlated with heart disease, diabetes, smoking. We know that one in five U.S. adults are still smoking. A lot of that smoking is going on in this population.

Unintentional injuries, traffic accidents, and drug overdoses, particularly prescription drug abuse emerging now in the data as another big cause of mortality in this population.

GWEN IFILL:But, at least in one of these studies—one was from the University of Wisconsin, one was from the University of Washington—at least in one, they said that male mortality figures were holding steady. Why aren't men more affected?

SUSAN DENTZER:Well, it's been true over time that female life expectancy is generally longer than male life expectancy anyway.

So it's not as if the situation is completely rosy for men. It is true, in the David Kindig study from the University of Wisconsin, that in three percent of U.S. counties, male mortality also is rising. So the men aren't held harmless here.

But the big effect has been I'm women, and particularly since we have been—we have been expecting women's life expectancy to be longer. What we now see is that, for women in particular with less than 12 years of education, so women who didn't make it out of high school, their life expectancy has actually fallen by four years since 1990.

And that means, overall, it's part of the equation that now has U.S. life expectancy looking so poor relative to all our other rich countries, all peer countries.

GWEN IFILL:Is there a regional way of pinpointing this, or demographics?

SUSAN DENTZER:Yes.

If you look at a map, it's concentrated in, say, Kentucky, Tennessee, West Virginia, down to what's known as the "Stroke Belt," Louisiana, Texas, over to the West—not so much California, interestingly.

And one interesting aspect of the story is that this is not a situation that is driven—it's not cropping up in the Hispanic population, for example. It's really more white lower-income populations in the Southern part of the country in particular.

GWEN IFILL:And we say 43—that number, 43 percent of counties, what number? Is there a way to say how many women are actually affected?

SUSAN DENTZER:Well, not necessarily from this study.

But if you think about it, we have about 3,000—3,100 U.S. counties or parishes or the equivalent. And so it's a hefty portion. It's not the most populous counties. The more populous counties tend to be, say, in the Northeast or in California. These are less populous areas of the country that still are very, very hard-hit by these phenomena.

GWEN IFILL:And are there trend lines that we should be watching, whether it's comparing what is happening here to what's happening in other countries, to just what's happening domestically?

SUSAN DENTZER:Well, what we know is our situation continues to worsen relative to all the other rich countries.

The Institute of Medicine published a study in January, "U.S. Health and International Perspective," that shows that our life expectancy is worse, that our mortality before age 50 is particularly driving the problem. That was emphasized also by Jessica Ho's study.

Again, we're—if you look—if you compare the years of life that Americans lose before the age of 50 relative to the average of all the other rich countries, we're double. We lose double the amount of life before age 50 of these other countries.

GWEN IFILL:Is there a way to pinpoint when this slide began? Is this something that is brand-new, or is this something that we have been able to document over time?

SUSAN DENTZER:We have been seeing this crop up in the data starting in the late '80s and early 1990s.

And one of the interesting factors that David Kindig, one of the authors, suggested is we really need to go back now and look at these data and see if they're correlated with any of our economic cataclysms that we have had.

GWEN IFILL:Right.

SUSAN DENTZER:Has that been driving any of this? Or it this just independent of economic forces, independent of unemployment rates, for example? That could be a driver.

We also know, of course, these are areas of the country where there's barely been any wage growth to speak of for many years. And we need to start to tease it across all of these economic and social factors that are driving this.

GWEN IFILL:So, your—there's an assumption somewhere in this that if you dig deep enough, you may find that the reason why it happens in certain counties and not in others is that these people who maybe don't have the resources may be eating a worse diet, may be more likely to smoke, may engage in behaviors that you might not do if you were more prosperous.

SUSAN DENTZER:And we know that the social and economic determinants of health, as they are called, are extremely powerful, and usually are driving differences in health status. And it's most likely that that's the case here.

What that means is that to tackle this is much more complicated than, for example, giving people access to health care.

GWEN IFILL:Right.

SUSAN DENTZER:That really isn't going to be the fix. It will be efforts to raise educational levels, create more economic growth in communities, secure access to high-wage jobs, create a healthy food environment, more activity for individuals, all of those things, a much, much broader agenda.

GWEN IFILL:How to turn it all around.

Susan Dentzer of "Health Affairs," thank you so much.

SUSAN DENTZER:Great to be with you, Gwen.