Journal
JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES
Volume 66, Issue 3, Pages 312-319Publisher
OXFORD UNIV PRESS INC
DOI: 10.1093/gerona/glq223
Keywords
Leukocyte telomere length; Aging; Longitudinal; Cross-sectional; African Americans; Whites; body mass index; sex
Categories
Funding
- National Institute of Child Health and Human Development [HD-061437, HD-062783]
- National Institute on Aging [AG-16592]
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Background. Leukocyte telomere length (LTL) is considered a biomarker of human aging and based on cross-sectional studies it shortens with age. However, longitudinal studies reported that many adults display LTL lengthening. Methods. Using Southern blots, we compared cross-sectional rates of age-related LTL change across a similar to 20 year age range with those based on longitudinal evaluations in three surveys (S1, S2, and S3) with three time intervals: S1-S2 (5.8 years). S2-S3 (6.6 years). and S1-S3 (12.4 years). Hierarchical linear modeling was used to explore LTL dynamics using LTL data from S1, S2, and S3. Results. Cross-sectionally, mean LTL shortenings were 24.6, 25.4, and 23.6 bp/y at S 1, S2, and S3, respectively. Longitudinally, more variation was observed in the rate of LTL change during the shorter than longer follow-up periods. Furthermore, using simple differences in LTL, 14.4% and 10.7% of individuals displayed LTL lengthening during S I S2 and S2-S3, respectively, but only 1.5% during S1-S3 (p < 0.001). The estimated mean rate of LTL shortening based on averaging empirical Bayes' estimates of LTL from a parsimonious hierarchical linear modeling model was 31 bp/y with a range from 23 to 47 bp/y with none of the participants showing LTL lengthening over the average 12.4 years of follow-up. Conclusions. As aging displays a unidirectional progression, it is unlikely that LTL elongates with age. LTL elongation in longitudinal studies primarily reflects measurement errors of LTL in relation to the duration of follow-up periods.
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