Psychoimmunological outcomes of a dementia caregiver intervention: The progressively lowered stress threshold

Abstract

<p>The goal of this study was to evaluate mood and immune outcomes of a community-based psychoeducational intervention (the Progressively Lowered Stress Threshold, PLST Model) designed to teach family caregivers to manage behavioral problems of persons with dementia. A randomized, repeated measures, experimental design was used to evaluate immune and mood outcomes of teaching the PLST model to family caregivers. Immune function (Natural Killer [NK] cytotoxicity and T-cell proliferation to Concanavalin A [Con A] and Phytohemagglutinin [PHA]) and mood states (Profile of Mood States) were compared between subjects receiving the six-month PLST intervention (experimental group) and subjects receiving a six-month placebo intervention of psychological support, traditional information, and referrals to community-based services (comparison group). Data was collected at baseline (T1), one week post-intervention (T2), and immediately after six months of telephone calls to support the intervention provided (T3). Interaction and main effects were evaluated using 2-way Repeated Measures ANCOVA with exploratory analyses conducted when main effects were significant. An alpha of .10 was used for all statistical analyses. Thirty-seven Caucasian family caregivers participated in the study. No interaction effects (group by time) were detected for immune or mood outcomes. While no main effects for time were detected, significant main effects for treatment group were observed for PHA, Con A, total mood disturbance, and all mood subscales, except anger. Cautionary exploratory analysis revealed that subjects in the experimental group demonstrated significantly higher levels of immune markers at T2 and T3 and significantly less total distress at T1 and T2 with significantly less confusion, depression, and fatigue, and more vigor at T1 and less confusion, depression, and fatigue at T2. Overall, these data do not support the hypotheses that the PLST intervention had an effect on immune or mood outcomes. However, the PLST intervention group demonstrated higher PHA and Con A proliferation than the comparison group. It is likely that the relatively large standard deviations and small sample size limited the power of this study to detect significant intervention-related improvements in immune or mood outcomes over time.</p>