Men and women who reached their mid-90s in 2010 were mentally sharper than those who hit that mark a decade earlier, according to a Danish cohort study.
The finding is a challenge to the "failure-of-success" hypothesis, in which increased longevity, caused by lowering death from chronic diseases, actually leads to an overall decline in the health of elderly people, according to Kaare Christensen, MD, of the University of Southern Denmark in Odense, Denmark, and colleagues.
Instead, they argued online in The Lancet, it implies that "more people are living to older ages with better overall functioning."
Christensen and colleagues compared two cohorts of Danes -- all people born in 1905, who were 92 and 93 in 1998 and all those born in 1915 and still living in 2010, at 94 and 95.
They assessed volunteers -- 63% of those eligible in both cohorts took part -- for both mental and physical abilities, using the same tests and methods in each cohort.
They tested cognitive ability using the mini-mental state examination, as well as a composite of five tests that are sensitive to age-related cognitive changes. Physical functioning was tested using an activities-of-daily-living score and by tests of grip strength, chair stand, and gait speed.
All told, 2,262 people in first cohort took part, as did 1,584 in second group.
The chance of surviving from birth to 93 was 28% higher in the 1915 cohort than in the 1905 cohort, Christensen and colleagues -- 6.5% compared with 5.06% -- while the proportion of those achieving 95 was 32% higher -- 3.93% versus 2.98%.
Despite their older age during the testing, the nonagenarians in the younger cohort did significantly better on the cognitive tests and were no worse -- and on one assessment was better -- on the physical tests, they reported.
- In the 1915 cohort, the average score on the mini-mental state examination was 22.8, compared with 21.4 for the 1905 group (P<0.0001).
- 23% of the younger group got maximum scores of 28 to 30 on the exam, compared with 13% of those in the 1905 cohort (P<0.0001).
- The cognitive composite score was also significantly better (P=0.0003) in the 1915 cohort -- 0.49 versus 0.01.
- There was no consistent difference in scores on the physical performance tests, such as grip strength and gait speed.
- However, the 1915 cohort had significantly better (P<0.0001) activities of daily living scores than did the 1905 cohort -- 2.0 versus 1.8.
While the results seem to support the notion that older people are arriving in their 10th decade in better condition than previously, the researchers cautioned that the findings are limited to one country and two birth cohorts born 10 years apart.
The outcomes may be different in other countries and indeed, the trend might not continue in later cohorts, they added.
Nonetheless, the study is a "a highly relevant contribution" to the debate over the effect of an aging population, argued Marcel Olde Rikkert, MD, PhD, and Rene Melis, MD, both of Radboud University Medical Centre in Nijmegen, the Netherlands.
In an accompanying comment article, they noted that some experts anticipate a sharp rise in dementia and other forms of morbidity as the proportion of very elderly people increases.
The Danish finding "challenges these extrapolations," they argued, and implies that "age-related cognitive decline in very elderly people is malleable."
The study had support from the Danish National Research Foundation, the NIH, the Danish Agency for Science, Technology and Innovation, and the VELUX Foundation. The journal reported that the authors had declared no conflicts of interest.
The journal also reported that the editorial authors had declared no conflicts of interest.
- Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner
The LancetSource Reference: Christensen K, et al "Physical and cognitive functioning of people older than 90 years: a comparison of two Danish cohorts born 10 years apart" The Lancet 2013; DOI: 10.1016/S0140-6736(13)6077