Christensen · BMJ (Clinical research ed.) 2009 · prospective cohort twin study · n=1826

Perceived age as clinically useful biomarker of ageing: cohort study.

Cited 208 times in the scientific literature.

Level 3 - non-randomized controlled study

Prospective cohort follow-up study

PubMed 20008378 · doi:10.1136/bmj.b5262 · record verified 2026-08-26

What was done

Perceived age was assessed from photographs of 1,826 Danish twins aged 70 or older by 41 independent assessors (20 nurses, 10 young men, and 11 older women). Researchers tracked survival through January 2008 and measured physical performance, cognitive function, and leucocyte telomere length to determine whether perceived age predicted mortality and biological ageing phenotypes.

What was found

During follow-up, 675 twins (37%) died. Across all three assessor groups, older perceived age was significantly associated with higher mortality after adjusting for chronological age, sex, rearing environment, and physical and cognitive functioning. Within twin pairs, the probability that the older-looking twin died first increased as the perceived age difference between them widened. Perceived age also correlated significantly with lower physical functioning, poorer cognitive test scores, and shorter leucocyte telomere length. Specific hazard ratios and correlation coefficients were not reported in the abstract.

Why it matters

Visual estimation of age serves as an independent, clinically accessible biomarker of biological ageing that reflects molecular and functional decline and predicts long-term survival.

Limits

The study was restricted to Danish twins aged 70 and older, limiting generalizability to younger populations and diverse ancestries. Specific numerical effect sizes, hazard ratios, and follow-up duration are not provided in the abstract. Photographic assessment may capture different visual cues than in-person clinical examination.

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