Caregiving is associated with low secretion rates of immunoglobulin A in saliva

Although the chronic stress of caring for a sick/disabled relative has been associated with poorer immunity using a range of outcomes, its impact on secretory immunoglobulin A (S-IgA) in saliva has yet to be examined. Three hypotheses were tested in analyses of data from a large community sample: first, caregivers would have lower S-IgA secretion rates than non-caregivers; second, the impact of care-giving on S-IgA would be particularly apparent in older participants; third, for caregivers, caregiving burden would be negatively associated with S-IgA. The sample comprised three distinct age cohorts, one young (N = 623), one middle aged (N = 639), and the other elderly (N = 582). Participants were classified as caregivers if they regularly cared for somebody other than routine childcare. Caregiving strain was measured and a caregiving burden index was then derived as the composite of the number of people being cared for, the type of care provided, and the residential status of the person being cared for. From 2-min saliva samples, S-IgA secretion rate was measured. There was a significant caregiver status by age cohort interaction; caregivers in the eldest cohort had lower S-IgA secretion rates than their non-caregiving counterparts. Caregiving strain and burden and S-IgA were related, such that caregivers who experienced greater strain and burden had lower S-IgA secretion rates. These findings resonate with those from other studies using different immune outcomes. Considered together, it is clear that that the chronic stress of caregiving has widespread effects on immunity. (c) 2007 Elsevier Inc. All rights reserved.