Relation of long-term patterns in caregiving activity and depressive symptoms to telomere length in older women

Background: Research links psychological stress to accelerated cellular aging. Here we examined whether long-term patterns of depression and caregiving burden, forms of chronic psychological stress, were associated with shorter telomere length, a biomarker of cellular aging. Methods: The study included 1250 healthy older women (mean: 68.0; range: 60-81 years) in the Nurses' Health Study. Long-term patterns in depressive symptoms and caregiving activity (separated into care of children/grandchildren vs. ill or disabled family members/others) incorporated questionnaire data between 1992 and 2000; relative leukocyte telomere lengths (LTLs) were measured in 2000-2001. Least-squares means LTL z-scores were calculated across categories of depression patterns and caregiving intensity. Results: Six empirically-derived latent classes of depressive symptom trajectories were identified: minimal-stable (63.7%), mild-worsening (3.9%), subthreshold-improving (22.8%), subthreshold-worsening (2.7%), clinical range depressive-improving (6.2%), and clinical range depressive-persistent (0.6%). After collapsing trajectory patterns into 4 groups (combining those with minimal and mild symptoms into one group and those with clinical range depressive symptoms into one group) due to very small sample sizes in some groups, we observed marginal associations (p = 0.07): e.g., the least-squares means LTL z-scores were lowest (-0.08; 95% CI: -0.22 to 0.06) for the clinical range depressive symptoms group and highest (0.12; 0.04-0.20) for the subthreshold-improving group (Tukey's post-hoc pairwise p = 0.07). With six depressive symptom trajectories, no significant associations were observed with regard to telomere lengths. There were no significant associations between caregiving intensity and LTLs. Conclusions: There were no associations between long-term patterns of caregiving burden and telomere lengths among older women. Possible differences in telomere lengths by types of long-term depressive symptom trajectories may warrant further investigation.