A team of danish researchers studied photographs and data on 1,826 Danish twins aged 70 or older who'd undergone physical and cognitive tests. The data came from the Longitudinal Study of Aging Danish Twins, which was begun in 1995, with assessments every two years up to 2005.
The facial photographs of the twins were evaluated by 20 female geriatric nurses aged 25-46, 10 male student teachers aged 22-37, and 11 women aged 70-87.
The assessors rated the perceived age by looking at pictures of the subjects' faces. They didn't know the age range of the twins, and each twin had his or her age assessed on different days.
Death records were used to track the survival of the twins over a seven-year period.
The researchers found that perceived age was significantly associated with survival and life span, even after adjusting for chronological age, gender, and the environment.
Perceived age, the researchers say, adjusted for chronological age and gender, also correlated with physical and cognitive functioning, as well as length of leukocyte telomeres; chromosome tips on DNA of people's white blood cells.
Shorter telomere length was associated with a “host of diseases related to aging and lifestyle factors and has been shown to be associated with mortality,” the researchers write.
The bigger the difference in perceived age within a twin pair, the more likely it was that the twin who looked older died first, the authors say.
Basing perceived age on facial photographs is thought to be a robust biomarker of aging that predicts survival in people 70 and over and correlates with important functional and molecular age-related characteristics, the authors conclude.
SOURCE: News release, BMJ.