title: Physical and cognitive functioning of people older than 90 years: a comparison of two Danish cohorts born 10 years apart.
abstract: BACKGROUND
  A rapidly increasing proportion of people in high-income countries are surviving into their tenth decade. Concern is widespread that the basis for this development is the survival of frail and disabled elderly people into very old age. To investigate this issue, we compared the cognitive and physical functioning of two cohorts of Danish nonagenarians, born 10 years apart.
  
  
  METHODS
  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). All cohort members were eligible irrespective of type of residence. 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).
  
  
  RESULTS
  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 (22·8 [SD 5·6] vs 21·4 [6·0]; p<0·0001), with a substantially higher proportion of participants obtaining maximum scores (28-30 points; 277 [23%] vs 235 [13%]; p<0·0001). Similarly, the cognitive composite score was significantly better in the 1915 than in the 1905 cohort (0·49 [SD 3·6] vs 0·01 [SD 3·6]; p=0·0003). 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 (2·0 [SD 0·8] vs 1·8 [0·7]; p<0·0001).
  
  
  CONCLUSIONS
  Despite being 2 years older at assessment, the 1915 cohort scored significantly better than the 1905 cohort on both the cognitive tests and the activities of daily living score, which suggests that more people are living to older ages with better overall functioning.
  
  
  BACKGROUND
  Danish National Research Foundation; US National Institutes of Health-National Institute on Aging; Danish Agency for Science, Technology and Innovation; VELUX Foundation.
authors.affiliation: Danish Aging Research Center, Institute of Public Health, University of Southern Denmark, Odense, Denmark; Max Planck Odense Center, University of Southern Denmark, Odense, Denmark; Department of Clinical Genetics, Odense University Hospital, Odense, Denmark; Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense, Denmark. Electronic address: kchristensen@health.sdu.dk.
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
authors.forename: Mikael
authors.initials: M
authors.lastname: Thinggaard
authors.forename: Anna
authors.initials: A
authors.lastname: Oksuzyan
authors.forename: Troels
authors.initials: T
authors.lastname: Steenstrup
authors.forename: Karen
authors.initials: K
authors.lastname: Andersen-Ranberg
authors.forename: Bernard
authors.initials: B
authors.lastname: Jeune
authors.forename: Matt
authors.initials: M
authors.lastname: McGue
authors.forename: James W
authors.initials: JW
authors.lastname: Vaupel
mesh_terms: D000203:Activities of Daily Living; D000369:Aged, 80 and over / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D003718:Denmark; D005260:Female; D006801:Humans; D008136:Longevity; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009483:Neuropsychological Tests; D011795:Surveys and Questionnaires; D013997:Time Factors