Introduction: As the number of older adults with dementia is increasing with the growing population of older adults, the need for informal caregivers has risen dramatically. Caregiving is associated with many rewards, and yet the negative impact of care on caregiver's mental health has been well-documented. However, since Schulz and Beach (1999)'s seminal study reported that caregivers who were experiencing caregiving strain had 63% higher mortality risks than same aged peers who were not caregivers, it is now recognized that for some, caregiving may be stressful, and as a result deadly. Since this foundational work, however, a number of studies have found that, in contrast, caregiving may reduce mortality risk (Brown et al., 2009; Caputo, Pavalko, & Hardy, 2016; Fredman, Lyons, Cauley, Hochberg, & Applebaum, 2015; Maguire, Rosato, & O'Reilly, 2016; O'Reilly, Rosato, Maguire, & Wright, 2015; Ramsay, Grundy, & Reilly, 2013). In other words, these findings are in line with the Healthy Caregiver hypothesis which suggests that healthy individuals enter the caregiving role and caregiving may maintain health. We expand on prior research by considering whether it is indeed the healthiest caregivers who experience a mortality benefit, and whether the protective effect is consistent for specific causes of mortality, particularly those related to the stress process (ex. cardiovascular disease).
Methods: Our nationally representative sample consisted of 17,816 adults aged 51 or older. Using fourteen years of data from the Health and Retirement study (2000-2014), Cox survival models were run in STATA predicting time to death for spousal caregivers of individuals with dementia with the time period starting from 2000 to the final available National Death Index data (2014). We first consider dementia caregiver status (having ever provided care for a spouse with dementia between 2000 and 2012) as a predictor of all-cause mortality controlling for caregiver demographics, smoking status, depressive symptoms, and self-rated health at baseline. Next we tested an interaction between caregiver status and self-rated health. Follow-up models consider dementia caregiver status as a predictor of leading causes of death mortality.
Results: Those who reported having ever served as a dementia caregiver for their spouse had a significantly lower hazard of all-cause mortality (HR = 0.64, CI = 0.60-0.69, p<.001) relative to those who hadn't served as a dementia caregiver. An interaction between caregiver status and self-rated health revealed that the protective effect of caregiving was strongest for caregivers with poor self-rated health (HR=0.66, CI=0.45-0.98, p<.05). The primary causes of caregiver death included heart disease (33%), cancer (24%), chronic lower respiratory disease (9%), and other causes (16%). Finally, caregiver status also showed a significant protective effect for heart disease, cancer, and cerebrovascular disease mortality.
Conclusions: Exploring the positive impact of caregiving on mortality, we found that for older adults in the poorest health, caregiving may make a positive difference. For example, caregiving may give spouses a reason to maintain their health so as to be able to provide the intensive care for their spouse that dementia requires. However, for those in good health, caregiving may do little to encourage or prevent healthy behaviors. Furthermore, accounting for competing risks, a similar protective effect of caregiving was found for three leading causes of mortality: cancer, heart disease, and cerebrovascular disease. Future work should attend to selection effects and reverse causation, however, to consider whether healthier individuals enter and stay in a caregiving role because those with poor health have already attrited from the population. In conclusion, these findings add to a growing body of literature which suggests that caregiving may provide a mortality benefit. We uniquely find that this protective effect spans causes of death and is strongest amongst those reporting poor health.