Stress, sleep problems, and immune function in persons with cancer histories

Problem. Data suggest that chronic stress, cancer history, sleep problems and clinical depression are associated with reduced natural killer cell activity (NKA), but few studies have examined whether in combination these variables have synergistic relationships with NKA. Because spouse caregivers of persons with Alzheimer's disease are chronically stressed, we assessed whether interactions of caregiving, cancer history, sleep problems and clinical depression/depressed mood would be associated with reduced NKA in 80 spouse caregivers and 85 age- and sex- matched non-caregiver controls. Methods. In the overall study the mean age was 69.5 years, the percent women was 67% and the percent Caucasian was 99%. Participants were assessed at study entry (Time 1) and 15 - 18 months later (Time 2). Using medical records/ICD-9 codes, we determined that persons with a cancer history (n = 43) had not been treated with immune altering medications for at least one year before NKA assessments. NKA was assessed by a chromium-release assay and all concentrations were averaged. Results. At Times 1 and 2, direct (univariate) relationships were weak or absent for caregiver status, cancer history, sleep problems, and clinical depression/depressed mood. In contrast, at both times synergistic (multivariate) relationships occurred for NKA with the three-way interaction of caregiver status, cancer history and sleep problems (p < .05). Hence, caregivers with cancer histories and sleep problems had lower NKA values (Time l, M ± SD = 22.9 ±2.8; Time 2, M= 27.7 ±4.1) than did individuals without all three factors (Time 1, M of 7 other strata combined = 33.1 ±1.2; Time 2, M = 33.7 ±1.1), p < .05. Over time, sleep problems at Time 1 were predictive of reduced NKA at Time 2 (r = -.65, p < .01), but this only occurred in caregivers with cancer histories. Conclusions. Synergistic effects may occur for NKA with sleep problems, chronic stress and cancer history, independent of depressed mood/clinical depression. © 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Harwood Academic Publishers imprint, part of the Gordon and Breach Publishing Group.

Duke Scholars

Author Ilene C. Siegler Psychiatry & Behavioral Sciences, Behavioral Medicine & Neur ...