Mitochondrial Health, Physical Functioning, and Daily Affect: Bioenergetic Mechanisms of Dementia Caregiver Well-Being.

OBJECTIVE: Chronic stress adversely affects mental and physical well-being. However, health outcomes vary among people experiencing the same stressor. Individual differences in physical and emotional well-being may depend on mitochondrial biology, as energy production is crucial for stress regulation. This study investigated whether mitochondrial respiratory capacity corresponds to individual differences in dementia spousal caregivers' mental and physical health. METHODS: Spousal caregivers of individuals with Alzheimer's disease and related dementias ( N = 102, mean age = 71, 78% female, 83% White) provided peripheral blood samples and completed self-report questionnaires on quality of life, caregiver burden, and a 7-day affect scale. Multiple and mixed linear regressions were used to test the relationship between mitochondrial biology and well-being. RESULTS: Spare respiratory capacity ( b = 12.76, confidence interval [CI] = 5.23-20.28, p = .001), maximum respiratory capacity ( b = 8.45, CI = 4.54-12.35, p < .0001), and ATP-linked respiration ( b = 10.11, CI = 5.05-15.18, p = .0001) were positively associated with physical functioning. At average ( b = -2.23, CI = -3.64 to -0.82, p = .002) and below average ( b = -4.96, CI = -7.22 to 2.70, p < .0001) levels of spare respiratory capacity, caregiver burden was negatively associated with daily positive affect. At above average levels of spare respiratory capacity, caregiver burden was not associated with positive affect ( p = .65). CONCLUSIONS: Findings suggest that higher mitochondrial respiratory capacity is associated with better psychological and physical health-a pattern consistent with related research. These findings provide some of the earliest evidence that cellular bioenergetics are related to well-being.

High Heart Rate Variability Buffers the Effect of Attachment Insecurity on Sleep Quality.

OBJECTIVE: Sleep quality is an important health-protective factor. Psychosocial factors, including attachment orientation, may be valuable for understanding who is at risk of poor sleep quality and associated adverse health outcomes. High attachment anxiety is reliably associated with adverse health outcomes, whereas high attachment avoidance is associated with adverse health outcomes when co-occurring with poor self-regulatory capacity, indexed by heart rate variability (HRV). We examined the associations between attachment anxiety, attachment avoidance, HRV, and sleep quality. METHODS: Using longitudinal data from a sample of 171 older adults measured four times over 1 year ( M = 66.18 years old; 67.83% women), we separated the between-person variance (which we call "trait") and within-person variance (which we call "state") for attachment anxiety, attachment avoidance, and HRV (via the root mean square of successive differences). Sleep quality was measured with the Pittsburgh Sleep Quality Index. RESULTS: Higher trait attachment anxiety was associated with poorer global sleep quality ( B = 0.22, p = .005). Higher state attachment avoidance was associated with poorer sleep quality ( B = -0.13, p = .01), except for those with higher trait HRV. Higher state attachment anxiety was associated with poorer sleep quality ( B = -0.15, p = .002), except for those with higher or mean trait HRV. Higher trait attachment anxiety was associated with poorer sleep quality ( B = -0.31, p = .02), except for those with higher trait HRV. CONCLUSIONS: High trait HRV mitigated the adverse effects of attachment insecurity on sleep quality. Our results suggest that people with high trait HRV had greater self-regulation capacity, which may enable them to enact emotion regulation strategies effectively.

LPS-induced whole-blood cytokine production and depressive symptoms in dementia spousal caregivers: The moderating effect of childhood trauma.

Dementia spousal caregivers are at risk for adverse mental and physical health outcomes. Caregiver burden, anticipatory grief, and proinflammatory cytokine production may contribute to depressive symptoms among caregivers. People who report childhood trauma are more likely to have exaggerated stress responses that may also contribute to depressive symptoms in adulthood. This study aimed to test whether the relationship between whole-blood cytokine production and depressive symptoms is strongest in caregivers who report high levels of childhood trauma. METHODS: A sample of 103 dementia spousal caregivers provided self-report data on demographics, health information, caregiver burden, anticipatory grief, and depressive symptoms. We also determined lipopolysaccharide-induced whole-blood cytokine production as the primary measure of immune cell reactivity. We measured interleukin-1ß (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) and converted z-scores of each cytokine into a composite panel. We regressed depressive symptoms on proinflammatory cytokine production, caregiver burden, and anticipatory grief, adjusting for demographic and health-related covariates. RESULTS: Whole-blood cytokine production and childhood trauma were associated with depressive symptoms. Childhood trauma moderated the relationship between whole-blood cytokine production and depressive symptoms. Whole-blood cytokine production was only associated with depressive symptoms at mean and high levels of childhood trauma, but not at low levels of childhood trauma. The main effects of burden and anticipatory grief on depressive symptoms were strongest for caregivers reporting high levels of childhood trauma. DISCUSSION: Childhood trauma has lasting impacts on psychosocial experiences later in life and has effects that may confer susceptibility to inflammation-related depression. Our findings contribute to ongoing efforts to identify risk factors for adverse mental health in dementia spousal caregivers.