Psychobiological Monitoring of a Home-Based Dyadic Intervention for People Living with Dementia and Their Caregivers: Added Value to Evaluate Treatment Success and Understand Underlying Mechanisms.

Background: Research concerning people living with dementia (PwD) and their informal caregivers (ICs) has recently begun to focus on dyadic aspects of psychosocial interventions.

Objective: We adapted a dyadic psychosocial intervention and examined its effects on psychobiological stress in daily life.

Methods: Twenty-four PwD-caregiver dyads were visited seven times at home by specialized nursing staff. Momentary subjective stress, salivary cortisol (sCort), and salivary alpha-amylase (sAA) were measured in PwD and ICs before and after each home visit as well as six times per day at two days each at the beginning and end of the intervention as part of an ambulatory assessment. Hair cortisol concentrations (HCC) were measured twice.

Results: After each home visit session, ICs reported lower subjective stress. sCort was lower in both ICs and PwD, whereas sAA did not change. In daily life, area under the curve (AUCg) concerning sCort secretion indicated that PwD had lower sCort daily output at the end of the intervention, and AUCg concerning subjective stress indicated that both PwD and ICs reported lower subjective stress than at the beginning of the intervention. AUCg concerning sAA did not change over time in either group. HCC did not vary over time but increased with disease severity.

Conclusion: The psychosocial intervention reduced psychobiological stress but affected psychobiological stress measures differently in PwD and ICs. In particular, the discrepancy between subjective and physiological markers of stress in PwD emphasizes the added value to evaluate treatment success and understand underlying mechanisms as a complement to self-reports.