In the first study of its kind, University of Southern California researchers have identified a number of surprising factors linked to how much we shrink as we grow older.
On average, the overall height loss for men is 3.3 cm, and for women, 3.8 cm. Using data from a longitudinal survey of more than 17,000 adults beginning at age 45, the researchers showed for the first time that adult lifestyle choices – and not just the hand we’re dealt as children – influence how much height we lose as we age. “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,” said John Strauss, an investigator on the study.
The study, appearing in the American Economic Journal: Applied Economics, revealed an especially strong relationship between height loss and cognitive health. Participants 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.
Some of the socioeconomic factors linked to height loss included:
- Urban dwellers had much less height loss than those in rural areas.
- Having completed primary school was associated with 0.9 cm less height shrinkage in men and 0.6 cm in women.
- Completing high school meant an additional 1 cm less in shrinkage.
“Height has been recognized as an acceptable proxy for childhood health conditions, but there are complications there,” says 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.”
All humans go through physical changes with age, including an increase in body fat and decrease in bone mass. But Ridder notes that a decrease in height can be further exacerbated by certain kinds of arthritis, inflammation of spine joints or osteoporosis, which other studies have shown are associated with such lifestyle choices as diet, exercise and smoking.
The researchers plan to follow-up with the same 17,708 people on a continuing basis, capturing, for the first time, critical data about human aging.
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