Brain Structural Markers and Caregiving Characteristics as Interacting Correlates of Caregiving Strain

Abstract

Objective To evaluate the association between brain structural markers and caregiving strain among older informal caregivers. Design A secondary data analysis combining data from the Caregiver Health Effects Study (1993-1994) and the Cardiovascular Health Study MRI examination (1992-1994). Setting Four United States communities. Participants Co-residing spousal caregivers (n=237, mean age=76.2, standard deviation=2.2). Measurements Visually-rated ventricular and white matter (WM) grades from MRI, caregiving strain defined as “emotional or physical strain associated with providing care” for any of 12 activities of daily living (ADLs) and instrumental activities of daily living (IADLs), plus measures of caregiving characteristics and caregiver's health. Results Overall, 56% of caregivers reported strain. We detected an interaction where strain was very common (>82%) among caregivers who helped with ≥4 IADLs, regardless of WM grades, and among caregivers with the worst WM grades (WM grades ≥4), regardless of the number of IADLs they helped with. Among caregivers helping with <4 IADLs, having WM grades ≥4 was associated with a 55% higher prevalence ratio for reporting strain. This association remained statistically significant but was most markedly attenuated by adjustments for: care recipient's memory and behavioral problems, caregiver's depression symptoms, and caregiver's ADL impairment. Conclusions Caregiving strain is very common among older informal caregivers who provide help with many IADLs, and among caregivers who help with fewer IADLs, but have manifest signs of white matter pathology. Modern quantitative-neuroimaging studies are needed to evaluate whether more subtle variability in brain structure confers caregiving strain and the related health consequences.

Caregiver Vulnerability and Brain Structural Markers: Compounding Risk

“…1 Intensive caregiving can produce a range of adverse mental and physical health consequences, best documented among dementia family caregivers. The provocative population-based study of the elderly by Smagula and colleagues, 2 drawn from a random, stratified sample, showed that more than 82% of those spouses who helped their partner with four or more of the 12 activities of daily living (ADLs) or instrumental activities of daily living (IADLs) reported strain, consistent with other literature. Caregivers who helped their partner with three or fewer IADLs, however, were 55% more likely to report strain if they had magnetic resonance imaging–assessed white matter grades of 4 or greater.…”

“…If this is the case, caregivers with such structural abnormalities would struggle to regulate their negative emotions in the face of caregiving demands, resulting in exaggerated and prolonged inflammatory responses—similar to the dysregulating effects of depression. 5 The co-occurrence of white matter hyperintensities with depression and mortality 2 further corroborates inflammatory responsiveness to stress as a plausible mediator of downstream health consequences.…”

“…2 They speculate, however, that the extensive white matter pathology developed over a more extended time interval than the spousal caregiving demands—a reasonable assumption. The risks for white matter damage include cardiovascular risk factors such as unhealthy diets, sedentary lifestyles, high blood pressure and cholesterol, and smoking, all factors that can be augmented by the elevated levels of stress and depression that are common issues among caregivers.…”

“…The risks for white matter damage include cardiovascular risk factors such as unhealthy diets, sedentary lifestyles, high blood pressure and cholesterol, and smoking, all factors that can be augmented by the elevated levels of stress and depression that are common issues among caregivers. 1,2 …”

“…The findings are particularly notable in view of the very broad definition used for caregiving: These researchers only required that the impaired spouse have difficulty with at least one ADL or IADL, “due to physical or health problems or problems with confusion.” 2 Accordingly, it is likely that their sample was considerably less burdened and less distressed than the caregivers who have received the most attention: spousal caregivers for dementia sufferers, the population most heavily represented in the studies they cite. Furthermore, their research participants only needed to meet criteria as caregivers at a single time point, so that spouses who were only functioning as temporary or transient caregivers following a partner’s acute medical problems would nonetheless be classified as caregivers in their data.…”