There is growing evidence linking caregiver stress with an increased risk for morbidity and mortality. While the emotional and practical burden experienced by caregivers is well established, the physiological changes that may affect the caregiver's health are less understood. This study sought to compare self-reported stress, anxiety and depression along with neuroendocrine and immune markers of stress among adult caregivers of allogeneic hematopoietic stem cell transplantation patients during the acute transplant recovery period to matched non-caregivers controls. Biomarkers and self-reported data were collected at three points during the patient's HSCT: (1) before transplant, (2) after initial transplantation discharge (±7 days) and (3) 6 weeks after initial transplantation discharge. Mixed linear modeling was used to examine differences by group and time. Twenty-one caregivers and 20 controls completed all study procedures. The majority of caregivers were female (57% or 57.1%) and married (95.2%), with a mean age of 52 ± 11.4 years. Caregiver perceived stress, anxiety and depression scores were significantly higher than controls (p < 0.001) with effect sizes (ES) ranging from 1.37 to 1.80 and they did not change over time (p > 0.05) for either group. Caregivers had significantly lower serum cortisol levels than controls at both discharge (p = 0.013; ES = 0.81) and 6 weeks after discharge (p = 0.028; ES = 0.72) but exhibited no significant relationship between self-reported stress and serum cortisol. In addition, caregivers showed a significant inverse relationship between stress and epinephrine levels (r(s)=-0.654, p = 0.021). These findings support the evidence of the caregiving experience being stressful. The counter-intuitive relationship between cortisol and epinephrine might suggest dysregulation of the HPA axis and central nervous system but additional research on the physiological impact of caregiving is warranted.
Keywords: Caregiver; biomarkers; burden; cancer; family; psychological; stress response; transplant.