It is well established from previous cross-sectional studies that telomeres shorten with age. However, due to a considerable inter-individual variation in telomere length (TL), its relationship with biological aging is difficult to unpick. Longitudinal repeated assessments of TL changes within individuals should augment our understanding of TL dynamics in aging. This study disentangles within- and inter-individual effects of age on leukocyte telomere length (LTL) dynamics in a large population-based cohort of older adults. A total of 4053 subjects aged 50 and older from the WHO Study on global AGEing and adult health (SAGE) in Shanghai were studied. Relative LTL (T/S ratio) was measured at baseline (2009–2010) and follow-up (2017–2018) by quantitative real-time polymerase chain reaction. We used linear random slope models to analyze LTL dynamics in relation to age and sex and within-subject centering method to distinguish within- versus between-subject effects. We observed LTL shortening in 66.32%, maintenance in 11.23%, and elongation in 22.45% of the study participants. LTL declined significantly with age both cross-sectionally and longitudinally. More importantly, the longitudinal decline in LTL was much greater than the cross-sectional decline (− 0.017 (p < 0.001) versus − 0.002 (p < 0.001) per year). Furthermore, women had a lower within-subject LTL shortening rate than men (− 0.014 versus − 0.020 per year, p < 0.001). The within-individual longitudinal decline in LTL was much greater than the inter-individual cross-sectional decline, indicating that chronological age might impose a greater impact on LTL shortening than other influencing factors combined. Moreover, women showed a lower within-individual LTL shortening rate than men.

之前的横断面研究已经明确表明，端粒会随着年龄的增长而缩短。然而，由于端粒长度（TL）存在相当大的个体差异，其与生物衰老的关系很难阐明。对个体内部 TL 变化的纵向重复评估应该会增强我们对衰老过程中 TL 动态的理解。这项研究在大型老年人群中阐明了年龄对白细胞端粒长度 (LTL) 动态的个体内部和个体间影响。世界卫生组织在上海开展的全球老龄化与成人健康研究（SAGE）共有 4053 名 50 岁及以上的受试者接受研究。通过定量实时聚合酶链式反应在基线（2009-2010 年）和随访（2017-2018 年）测量相对 LTL（T/S 比）。我们使用线性随机斜率模型来分析与年龄和性别相关的 LTL 动态，并使用受试者内中心方法来区分受试者内和受试者间的影响。我们观察到，在研究参与者中，66.32% 的零担运输缩短，11.23% 的零担运输维持，22.45% 的零担运输延长。无论是横向还是纵向，LTL 都随着年龄的增长而显着下降。更重要的是，LTL 的纵向下降远大于横向下降（每年− 0.017 ( p < 0.001) 与 − 0.002 ( p < 0.001)）。此外，女性的受试者内 LTL 缩短率低于男性（每年 - 0.014 与 - 0.020，p < 0.001）。零担的个体内部纵向下降远大于个体间的横断面下降，这表明实际年龄对零担缩短的影响可能比其他影响因素的总和更大。此外，女性的个体零担缩短率低于男性。