aging

Healthy habits keep adults from shrinking

USC (US) — Even if you didn’t eat your veggies or drink your milk as a child, you do have some control over your height as you age, research shows.

Using data from a massive longitudinal survey of 17,708 adults beginning at age 45, researchers show that lifestyle choices we make in adulthood influence how tall we stand as we age.

“Had we only examined the correlations between measured height and health, we would have missed this important insight,” says John Strauss, professor of economics at the University of Southern California and an investigator on the study in the American Economic Journal: Applied Economics.

“The evidence shows that it is not only early-life events that are associated with how we age, but health decisions in later life as well.”

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To estimate full adult height for older study participants, the researchers examined relationships between current height and the length of limbs, which do not shrink with age, from younger survey participants who have not yet started shrinking.

While prior work has looked for the connection between height and health—both in childhood and adulthood—the researchers are the first to examine height loss as we age. They show that regardless of your maximum height, the loss of height over time is also an important indicator for other health issues as we age.

For example, the research reveals an especially strong relationship between height loss and cognitive health. Those who had lost more height were also much more likely to perform poorly on standard tests of cognitive health such as short-term memory, ability to perform basic arithmetic and awareness of the date.

Literacy and height

Among the socioeconomic factors that correlate to height loss, urban dwellers had much less height loss than those in rural areas, the researchers found, in a country where there has been significant migration to urban areas in the last few decades.

In addition, having completed primary school, rather than being illiterate, is associated with 0.9 cm less height shrinkage in men—a large difference when considering that overall average height loss for men is 3.3 cm. Completing high school meant an additional 1 cm less in shrinkage.

For women, having completed primary school was the difference in 0.6 cm of shrinkage, compared to average overall height decrease of 3.8 cm.

“Height has been recognized as an acceptable proxy for childhood health conditions, but there are complications there,” says economist Geert Ridder, a co-investigator on the study. “Some of adult health might be determined by childhood circumstances, but people shrink differentially, and that shrinkage is also a measure of adult health conditions.”

The researchers used new data from the China Health and Retirement Longitudinal Study, The baseline for the survey was collected from June 2011 to March 2012 and includes both subjective self-reported responses to survey questions as well as objective physical measurements such as blood tests.

Follow-up studies

These physical measurements and personal interviews will be followed-up with the same 17,708 people every two years—capturing, for the first time, critical data about human aging in the most populous and most rapidly aging country in the world.

For example, recent changes in social security policy and health insurance in China provide a valuable opportunity for researchers to study how health care actually affects health and aging in a large population, with insights for other developing health care systems worldwide, as well as an opportunity to identify possible under-diagnosis of various chronic conditions.

The researchers will also be able to examine the role specific historical events in China may have had on long-term health, including whether there are health and aging differences among those who were “sent-down” during the Cultural Revolution.

The National Institute of Aging, the China Natural Science Foundation, the Fogarty International Center of the National Institutes of Health, and the World Bank supported the study.

Source: University of Southern California

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