The transition to family caregiving and its effect on biomarkers of inflammation.

Chronic stress has been widely proposed to increase systemic inflammation, a pathway that may link stress with a heightened risk for many diseases. The chronic stress-inflammation relationship has been challenging to study in humans, however, and family caregiving has been identified as one type of stressful situation that might lead to increased inflammation. Previous studies of caregiving and inflammation have generally used small convenience samples, compared caregivers with poorly characterized control participants, and assessed inflammation only after caregivers provided care for extended periods of time. In the current project, changes over a 9-y period were examined on six circulating biomarkers of inflammation for 480 participants from a large population-based study. All participants reported no involvement in caregiving prior to the first biomarker assessment, and 239 participants then took on extensive and prolonged family caregiving responsibilities at some point prior to the second biomarker assessment. Incident caregivers were individually matched on multiple demographic and health history variables with participants who reported no caregiving responsibilities. Of the six biomarkers examined, only tumor necrosis factor alpha receptor 1 showed a significantly greater increase in caregivers compared with controls. This effect was small (d = 0.14), and no effects were found for a subset of 45 caregivers who were living with a spouse with dementia. These results are consistent with recent meta-analytic findings and challenge the widespread belief that caregiving is a substantial risk factor for increased inflammation. Future research is warranted on factors that may account for stress resilience in family caregivers.