Table 1. Correlations between stress and cell senescence markers across the sample (adjusted for age and potential health/behavioral mediators).

	Perceived stress, n	Years of caregiving, n
Telomere length	-0.31* (-0.27†), 54	-0.40* (-0.43*), 36
Telomerase activity	-0.24† (-0.24†), 59	-0.35† (-0.32†), 37
Oxidative stress index	0.27† (0.22), 44	0.33† (0.38†), 30

Values are correlations adjusted for age only, with correlations adjusted for age, BMI, smoking, and vitamin use in parentheses. When people are stressed, some tend to eat and smoke more, and they may not engage in self-care behaviors, such as taking antioxidant multivitamin supplements. Therefore, potential mediators (BMI, smoking, and vitamin use) were controlled for along with age. Even when these factors are controlled for, stress was still significantly associated with shorter telomeres and lower telomerase activity, although the relationship with oxidative stress index was no longer significant and thus partially mediated by health behaviors. Perceived stress was not directly related to isoprostanes (r = 0.18, P value not significant) or vitamin E (r = -0.09, P value not significant) but was related to the oxidative stress index (the ratio of isoprostanes divided by vitamin E levels). †, P < 0.01; ‡, P < 0.05 (one-tailed). n values vary because of missing data, because years of caregiving was measured in the caregivers only, or because oxidative stress was measured on a subset of the sample (n = 44).