An exceptionally long lifespan does not necessarily mean living more years with disease and disability. It seems that centenarians tend to live their extra years in good health, with illness striking decades later in life compared with younger counterparts.
This was the conclusion researchers came to after examining the health status of 3,000 centenarians and near-centenarians taking part in two ongoing longevity studies.
Led by Nir Barzilai – a professor of medicine and of genetics at Albert Einstein College of Medicine in Bronx, NY – they report their findings in the Journal of the American Geriatrics Society.
Although centenarians make up only a small proportion of the world’s population, their share is growing.
In 1990, there were 2.9 people aged 100 and over for every 10,000 people aged 65 and older around the world. By 2015, that share had grown to 7.4 and is expected to reach 23.6 by 2050.
In the United States, there are estimated to be 2.2 centenarians per 10,000 people, or about 72,000 in total.
However, while at 61,000, Japan has fewer centenarians in total than the U.S. It has 4.8 per 10,000, the highest proportion in the world, closely followed by Italy at 4.1.
But does the fact more people are living exceptionally long lives mean they will live those extra years in poor health?
To examine this question, Prof. Barzilai and colleagues looked at the health status of centenarians and near-centenarians taking part in the Longevity Genes Project (LGP) and the New England Centenarian Study (NECS).
The team has been conducting the LGP since 1998. The study recruits healthy, Ashkenazi Jewish people aged 95 and older living independently in the northeastern U.S. For comparison, the cohort includes younger seniors and individuals with and without a family history of longevity.
The NECS began in 1994 as a study of centenarians living near Boston, MA, and has since expanded to cover individuals from further afield in North America, England, Ireland, Australia, and New Zealand. This study also includes seniors under the age of 95 for comparison.
For their investigation, Prof. Barzilai and colleagues compared the health of long-lived (age 95 and over) against younger seniors (age around 60-95) in both the LGP and the NECS.
From the LGP data, they compared 483 people with exceptional longevity against 696 younger seniors, and from the NECS data, they compared 1,498 long-lived people with 302 younger counterparts.
In both the LGP and the NECS populations, the team looked at the ages when participants developed five age-related major health problems or diseases: cancer, cardiovascular disease, high blood pressure, osteoporosis, and stroke.
The researchers found in both groups that onset of illness was consistently delayed in the centenarians, compared with younger seniors.
In the NECS group, cancer did not begin to affect 20 percent of the long-lived men until age 97, and long-lived women until 99. In comparison, among the younger seniors, 20 percent of the men got cancer by age 67 and women by age 74.
Similar patterns were found in the LGP participants. Among long-lived individuals, the age when 20 percent had developed cancer was 96 for both men and women. In contrast, 20 percent of younger LGP seniors had developed cancer some 20 years earlier: by age 78 for men and age 74 for women.
The two groups – LGP and NECS – are genetically, culturally and socially distinct, yet their results are markedly similar: in their centenarians, illness was compressed into a few years very late in life.
The team says this would suggest the findings are likely to be true of other populations, and contradict the idea that the older people get, the greater the burden they place on society in terms of their medical needs.
The researchers also conclude these groups should be studied further to discover which factors they have in common that influence the delay of a broad range of diseases that are usually associated with death and disability.
“Most people struggle with an ever-increasing burden of disease and disability as they age, but we found that those who live exceptionally long lives have the additional benefit of shorter periods of illness – sometimes just weeks or months – before death.”
Prof. Nir Barzilai