There May be No Such Thing as "Good" Cholesterol

The control of cardiovascular disease has been an important reason for the continued rise in life expectancy, especially in the richer countries. One of the most important risk factors for a heart attack (myocardial infarction) is high cholesterol. When we use that term generically we mean high levels of LDL (low-density lipoprotein), which causes clotting of the arteries that can then lead to a potentially fatal heart attack. LDL can be lowered by changes in diet (and exercise), often combined with drugs called statins. LDL is the "bad" cholesterol, whereas HDL (high-density lipoprotein) cholesterol has long been considered to be a "good" cholesterol, because people with high HDL are known to have a lower probability of a heart attack. As a consequence, a lot of effort (albeit largely unsuccessful) has gone into figuring out ways to raise HDL. However, a new study just published in The Lancet and reported in the New York Times suggests that the relationship between HDL and heart attack may not be causal. If this is true, then trying to raise your HDL is unlikely to save your life.

The study’s authors emphasize that they are not questioning the well-documented finding that higher HDL levels are associated with lower heart disease risk. But the relationship may not be causative. Many assumed it was because the association was so strong and consistent. Researchers also had a hypothesis to explain how HDL might work. From studies with mice and with cells grown in the laboratory, they proposed that HDL ferried cholesterol out of arteries where it did not belong.
Now it seems that instead of directly reducing heart disease risk, high HDL levels may be a sign that something else is going on that makes heart disease less likely. To investigate the relationship between HDL and cardiovascular risk, the researchers, led by Dr. Sekar Kathiresan, director of preventive cardiology at Massachusetts General Hospital and a geneticist at the Broad Institute of M.I.T. and Harvard, used a method known as Mendelian randomization. It is a study design that has recently become feasible with the advent of quick and lower-cost genetic analyses.
The study found, as expected, that gene variations that raise LDL increase risk and those that lower LDL decrease risk. The gene effects often were tiny, altering LDL levels by only a few percent. But the data, involving tens of thousands of people, clearly showed effects on risk.
“That speaks to how powerful LDL is,” Dr. Kathiresan said.
But the HDL story was very different. First the investigators looked at variations in a well-known gene, endothelial lipase, that affects only HDL. About 2.6 percent of the population has a variation in that gene that raises their HDL levels by about 6 points. The investigators looked at 116,000 people, asking if they had the variant and if those who carried the HDL-raising variant had lower risk for heart disease.
“We found absolutely no association between the HDL-boosting variant and risk for heart disease,” Dr. Kathiresan said. “That was very surprising to us.”

So, if these results are to be believed, it is still very important to lower LDL--that can save your life, as expected. But, trying to do alter your HDL may just be a waste of time.

Whites Now Account For Less Than Half of Births in the US

The top news story in the US today was the release of a set of population estimates by the Census Bureau showing that last year, for the first time in history, minority groups accounted for a majority of children under the age of one. I saw the story first in the New York Times.

Non-Hispanic whites accounted for 49.6 percent of all births in the 12-month period that ended last July, according to Census Bureau data made public on Thursday, while minorities — including Hispanics, blacks, Asians and those of mixed race — reached 50.4 percent, representing a majority for the first time in the country’s history.The trend toward greater minority births has been building for years, the result of the large wave of immigration here over the past three decades. Hispanics make up the majority of immigrants, and they tend to be younger — and to have more children — than non-Hispanic whites. (Of the total births in the year that ended last July, about 26 percent were Hispanic, about 15 percent black, and about 4 percent Asian.)
Whites still represent the single largest share of all births, at 49.6 percent, and are an overwhelming majority in the population as a whole, at 63.4 percent. But they are aging, causing a tectonic shift in American demographics. The median age for non-Hispanic whites is 42 — meaning the bulk of women are moving out of their prime childbearing years.

The problem, of course, is that older whites may not feel the same generational bonding with minority children and it is from that changing face of the youth that some of the angst stems among older Americans. On the other hand, those kids will be the ones paying the bills for the elderly.

And the fact that the country is getting a burst of births from nonwhites is a huge advantage, argues Dowell Myers, professor of policy, planning and demography at the University of Southern California. European societies with low levels of immigration now have young populations that are too small to support larger aging ones, exacerbating problems with the economy.
“If the U.S. depended on white births alone, we’d be dead,” Mr. Myers said. “Without the contributions from all these other groups, we would become too top-heavy with old people.”

Still, there are enormous challenges, especially around education, as William Frey at Brookings noted:

A college degree has become the most important building block of success in today’s economy, but blacks and Latinos lag far behind whites in getting one. According to Mr. Frey, just 13 percent of Hispanics and 18 percent of blacks have a college degree, compared with 31 percent of whites.

You can see and hear Bill Frey say these things himself on the PBS News Hour. 

Are America's "Elite" Women Ramping Up Their Fertility?

Thanks to Justin Stoler for pointing out a news item from futurity.org generated by a paper just published in the Journal of Population Economics. The authors--Qingyan Shang of The University at Buffalo and Bruce Weinberg of The Ohio State University--have found evidence that highly educated women in the United States have been having more children than in the past. The negative relationship between fertility and education is about as close to an "iron law" as you will find in demography, so this is very interesting news.

While it is still too early to be certain, research clearly shows fertility rising for older, highly educated women since the 1990s. (Fertility is defined as the number of children a woman has had.) Childlessness also declined by roughly 5 percentage points between 1998 and 2008.
“Women born in the late 1950s are the turning point,” says Qingyan Shang, assistant professor of economics at the University at Buffalo. Members of this group initially showed low fertility. But fertility increased for them when they reached their late 30s and early 40s.

The analysis pulled together data from the Census Bureau's Current Population Survey along with Vital Statistics from the National Center for Health Statistics of the US Centers for Disease Control.

The research did not directly address what factors might be contributing to the fertility increase. “We did list some possible explanations based on previous research,” says Shang, including the idea of “the learning story,” in which decisions of previous generations inform later decisions by subsequent generations.
There has also been an increased supply of personal services that have reduced childcare expenses. Other research shows men may be taking more responsibility for child care.Whether women are choosing families instead of or in addition to their careers is unclear, Shang says.“We know these women are opting for families. We don’t know if they in turn are opting out of the labor market.”The study also indicated an increase in multiple birth rates around 1990, suggesting fertility treatments may have played a role.

There is a lot of food for thought here, which should inspire follow-on research efforts. In the past, women really had to make a choice between education--especially if that was used to launch a career--and the number of children. More help around the house and more help from reproductive biology may be changing this dynamic.

Baby Boomers Are Working, Not Retiring, in Response to the Economy

Thanks to my colleague, Shoshana Grossbard, for pointing out a recent analysis of labor force data showing that the economic downturn of the past several years has had the effect of keeping baby boomers in the labor force longer than they anticipated. The story is in the Investor's Business Daily.

As the jobs crisis wears on, with payrolls still 5 million below their pre-recession peak, the share of age 55-and-older Americans working has recovered to near a 42-year high.
Workers under 55 have borne the brunt of the jobs recession, which may mean that its economic effects — due to long-term unemployment, underemployment and stretched household balance sheets — may linger.
Among those 55-and-up, the employment-to-population ratio barely dipped even in the depth of recession and is now higher than at the end of 2007. The ratio among those 25-54 remains about 4 percentage points lower than before the recession started.
For the 65-69 and 70-74 groups, the employed shares are up 1.1 percentage points and 1.6 percentage points, respectively, over the past four years.

Older workers often have the kinds of skills that keeps them valuable in the labor force, if they choose to stay. That choice is clearly driven by a person's calculation of what their standard of living will be if they leave the labor force. Social Security pensions in the United States are designed to supplement income in retirement, but not replace it. The only way to retire successfully is to have saved enough money to do so. Of course, many baby boomers thought they had done this, only to have their savings devastated by the economic crisis brought on by the banking failures. And that is why they continue in the labor force--trying to match up assets with the expected number of years for which they will need a retirement income. Keep in mind that this number of years is steadily growing, which is why younger people today will not receive full Social Security benefits until age 67 (which still may be too young).

House Votes to Lower Census Bureau's Budget--What Are They Thinking?

A few days ago, the members of the Population Association of America were alerted by email to an impending vote in the US House of Representatives aimed at cutting the budget of the Census Bureau. HR 3256 included, among other things, a provision to make the American Community Survey voluntary--a move that, if ultimately enacted--would severely limit its value. I was remiss in not blogging about this, but I did contact my Member of Congress, who nonetheless voted for this bill. Of the five Members of Congress from San Diego County, two voted for it, two voted against, and one (who is busy running for mayor of San Diego) failed to vote. That closely follows the overall vote, which was very close. The vote was a subject of an editorial in today's New York Times:

The Web site of Representative Daniel Webster, Republican of Florida, instructs visitors to click on a link for “Census data for the 8th district” to learn about the area’s economy, businesses, income, employment, homeownership and other important features. And yet, on Wednesday, Mr. Webster declared that the Census Bureau’s American Community Survey — the source for much of that data — is an unconstitutional breach of privacy.He then proposed an amendment to the bureau’s 2013 appropriation to forbid any money from being spent on the survey; the amendment was passed by most House Republicans and four Democrats.

As I pointed out to my own congressman, the cry throughout the nation is to create more jobs, but to do that businesses need information. The census, of which the American Community Survey is an integral part, is our main source of information about the United States. Without that information, we are truly walking in the dark. 

When Republicans proposed similar cuts last year, even the deficit hawks at the United States Chamber of Commerce opposed them.
The White House is opposed to the cuts and the Senate will soon have a chance to reject them when it takes up the appropriation bill. It should.

But let's not just hope that will happen. Contact your senators and push the case.