If asked yesterday, I'd have guessed that there wasn't a great deal of difference in the majority of the life history of people born ten years apart in the early 1900s in Europe: a small incremental improvement in adult life expectancy for those born later and a larger improvement in life expectancy at birth due to lowered infant mortality. Advances in medicine are weighted towards the recent past: progress is speeding up and practical improvements in medical technology - and patient outcomes - are presently arriving far more rapidly than, say, fifty or a hundred years ago. So the study noted below may be largely measuring improvements in medical care for the elderly that have taken place across the past few decades rather than anything that happened prior to that.
We compared the cognitive and physical functioning of two cohorts of Danish nonagenarians, born 10 years apart. People in the first cohort were born in 1905 and assessed at age 93 years (n=2262); those in the second cohort were born in 1915 and assessed at age 95 years (n=1584). Both cohorts were assessed by surveys that used the same design and assessment instrument, and had almost identical response rates (63%). Cognitive functioning was assessed by mini-mental state examination and a composite of five cognitive tests that are sensitive to age-related changes. Physical functioning was assessed by an activities of daily living score and by physical performance tests (grip strength, chair stand, and gait speed).
The chance of surviving from birth to age 93 years was 28% higher in the 1915 cohort than in the 1905 cohort (6.50% vs 5.06%), and the chance of reaching 95 years was 32% higher in 1915 cohort (3.93% vs 2.98%). The 1915 cohort scored significantly better on the mini-mental state examination than did the 1905 cohort, with a substantially higher proportion of participants obtaining maximum scores. Similarly, the cognitive composite score was significantly better in the 1915 than in the 1905 cohort. The cohorts did not differ consistently in the physical performance tests, but the 1915 cohort had significantly better activities of daily living scores than did the 1905 cohort. [These results suggest] that more people are living to older ages with better overall functioning.