Perceived age as clinically useful biomarker of ageing: cohort study

Abstract

Objective: To determine whether perceived age correlates with survival and important age related phenotypes.

Design: Follow-up study, with survival of twins determined up to January 2008, by which time 675 (37%) had died.

Setting: Population based twin cohort in Denmark.

Participants: 20 nurses, 10 young men, and 11 older women (assessors); 1826 twins aged >or=70.

Main outcome measures: Assessors: perceived age of twins from photographs. Twins: physical and cognitive tests and molecular biomarker of ageing (leucocyte telomere length).

Results: For all three groups of assessors, perceived age was significantly associated with survival, even after adjustment for chronological age, sex, and rearing environment. Perceived age was still significantly associated with survival after further adjustment for physical and cognitive functioning. The likelihood that the older looking twin of the pair died first increased with increasing discordance in perceived age within the twin pair-that is, the bigger the difference in perceived age within the pair, the more likely that the older looking twin died first. Twin analyses suggested that common genetic factors influence both perceived age and survival. Perceived age, controlled for chronological age and sex, also correlated significantly with physical and cognitive functioning as well as with leucocyte telomere length.

Conclusion: Perceived age-which is widely used by clinicians as a general indication of a patient's health-is a robust biomarker of ageing that predicts survival among those aged >or=70 and correlates with important functional and molecular ageing phenotypes.

Fig 1 Composite pictures each representing average appearance of groups of 10 twins aged 70 (range 69-71). Left hand image represents twins who looked younger for their age (average perceived age 64, range 57-69) than those represented by right hand image (average perceived age 74, range 70-78)

Fig 2 Comparison within pairs of dizygotic twins, showing proportions of pairs in which older looking twin died first. P values are two sided for standard binomial test. Numbers above x axis indicate absolute number of pairs in which older looking twin died first divided by total number of pairs

Fig 3 Comparison within pairs of monozygotic twins, showing proportions of pairs in which older looking twin died first. P values are two sided for standard binomial test. Numbers above x axis indicate absolute number of pairs in which older looking twin died first divided by total number of pairs