Caregiver Sleep, Depression and Stress: Impact on Immune, Endocrine and Inflammatory Biomarkers

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Background: Historically there have been consistent findings of immune dysfunction in informal caregivers, particularly those caring for someone with dementia. But there has been little work to understand what characteristics of the caregiving role beyond a general level of stress might be accounting for the immune dysfunction. In this study, we hypothesize that poor sleep and depression will have an effect on immune dysfunction when stress levels are controlled.

Methods: A cross-sectional study was conducted with 7 days of subjective and objective sleep recordings in addition to 2-day collection of saliva for cortisol and IgA levels, and a blood sample for immune and inflammatory measures. Caregivers of persons with dementia were recruited from a memory disorder clinic. Caregiver's ages ranged from 26-85 (mean = 66) and were 73% female, mostly spouses. On average, care recipients had moderate levels of dementia and 6 behavioral symptoms.

Results: Caregivers had low levels of total sleep time in both actigraphy and sleep diary measurements over 7 nights (425 ± 72; 427 ± 77, respectively). Stress scores were high (PSS = 39 ± 10). High stress levels were associated only with low total sleep time from actigraphy, not with total wake times, or total wake and sleep times from sleep diary. High stress levels were associated with lower interferon-gamma, TNF-alpha, IL-10, and IL-2. Low amounts of sleep at night were also associated with lower levels of TNF-alpha and IL-10. Partial correlations between TNF-alpha, IL-10 and minutes of sleep remained high even after stress was controlled. Depression had little effect on immune markers. Subsequent analyses will be presented that identify profiles of immune/endocrine dysfunction based on stress and sleep profiles, as well as profiles of caregiver distress of behavioral symptoms of dementia.

Conclusions: Since immune changes are consistently demonstrated in caregivers with high levels of stress, it is critical to understand what aspects of the caregiver role might be contributing to those abnormalities beyond the perception of stress. We believe that the sleep changes associated with stressed caregivers may be contributing to the immune changes. Suppressed immune function is seen in non-caregivers with poor sleep, so this may be a factor in immune dysfunction in caregivers as well.

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Citation / Publisher Attribution

Alzheimer's & Dementia, v. 8, issue 4, p. P380-P381