Background: A growing body of literature suggests that caregiving burden is associated with impaired immune system functioning, which may contribute to elevated morbidity and mortality risk among dementia caregivers. However, potential mechanisms linking these relationships are not well understood. The purpose of this study was to investigate whether stress-related experience of depressive symptoms and reductions in personal mastery were related to alterations in ß2-adrenergic receptor sensitivity.
Methods: Spousal Alzheimer's caregivers (N = 106) completed measures assessing the extent to which they felt overloaded by their caregiving responsibilities, experienced depressive symptoms, and believed their life circumstances were under their control. We hypothesized that caregivers reporting elevated stress would report increased depressive symptoms and reduced mastery, which in turn would be associated with reduced ß2- adrenergic receptor sensitivity on peripheral blood mononuclear cells (PBMC), as assessed by in vitro isoproterenol stimulation.
Results: Regression analyses indicated that overload was negatively associated with mastery (β = −0.36, p = 0.001) and receptor sensitivity (β = −0.24, p = 0.030), whereas mastery was positively associated with receptor sensitivity (β = 0.29, p = 0.005). Finally, the relationship between overload and receptor sensitivity diminshed upon simultaneous entry of mastery. Sobel's test confirmed that mastery significantly mediated some of the relationship between overload and receptor sensitivity (z = −2.02, p = 0.044).
Conclusions: These results suggest that a reduced sense of mastery may help explain the association between caregiving burden and reduced immune cell ß2-receptor sensitivity.