Abstract
IMPORTANCE: Multicomponent interventions for informal caregivers of people with dementia are urgently needed, but evidence regarding which components are most effective is lacking. OBJECTIVE: To apply a multiphase optimization strategy to examine the effects of 5 psychosocial components of an intervention designed to support informal caregivers of people with dementia. DESIGN, SETTING, AND PARTICIPANTS: In this assessor-blinded randomized clinical trial with a fractional factorial design, Chinese community-dwelling adults (aged ≥18 years) who were informal family caregivers of people with dementia were screened between July 2 and December 28, 2022, in Hong Kong. Eligible participants with elevated depression or caregiving burden were included and randomized to 1 of 16 experimental conditions. Assessments were conducted at baseline, 6 months, and 12 months. The last 12-month follow-up assessment was conducted on February 26, 2024. INTERVENTIONS: The intervention involved a core component (dementia caregiving education) and 5 tested psychosocial components (self-care skills [SC], behavioral problem management [BPM], behavioral activation [BA], mindfulness-based intervention [MBI], and support group [SG]). MAIN OUTCOMES AND MEASURES: Primary outcomes for each tested psychosocial component were physical health (12-item Short-Form Health Survey), caregiver burden (12-item Zarit Burden Interview) and stress (10-item Perceived Stress Scale), psychological well-being (Ryff Psychological Well-Being Scale), anxiety (Hospital Anxiety and Depression Scale-Anxiety Subscale), depressive symptoms (9-item Patient Health Questionnaire), and social support (20-item Medical Outcomes Study Social Support Survey). Multiple linear regression models were used to analyze score changes from baseline to 6 months and from baseline to 12 months for primary and proximal outcomes across the 5 components. RESULTS: This trial included 250 caregivers (mean [SD] age, 48.9 [13.8] years); most (171 [68.4%]) were female. The MBI component significantly improved multiple caregiver outcomes, with reduced depressive symptoms (β = -2.13 [95% CI, -2.85 to -1.38]; P < .001) and increased mindfulness (β = 4.23 [95% CI, 2.27-6.36]; P < .001), perceived social support (β = 4.76 [95% CI, 1.28-8.15]; P = .007), and active dementia care management (β = 3.70 [95% CI, 1.80-5.66]; P < .001) at 12 months. The SG component significantly improved perceived social support (β = 4.63 [95% CI, 1.32-7.85]; P = .006) at 12 months. BPM had mixed effects; that is, it initially increased caregiver anxiety (β = 1.43 [95% CI, 0.43-2.42]; P = .005) and self-care risk (β = -1.12 [95% CI, -1.82 to -0.43]; P = .002) at 6 months but improved dementia care strategies in terms of encouragement (β = 2.49 [95% CI, 0.74-4.22]; P = .005), active management (β = 5.99 [95% CI, 4.12-7.84]; P < .001), and psychological well-being (β = 3.52 [95% CI, 0.92-6.08]; P = .008) at 12 months. Interaction effects were observed, with the MBI component enhancing the benefits of SC (β = -1.70 [95% CI, -3.05 to -0.35]; P = .01) and BPM (β = -1.40 [95% CI, -2.76 to -0.05]; P = .04) on depression; meanwhile, the MBI and SG components synergistically improved perceived social support (β = 7.58 [95% CI, 0.90-14.26]; P = .03). CONCLUSIONS AND RELEVANCE: In this clinical trial of informal caregivers of people with dementia, synergistic interaction effects were noted for MBI, which enhanced the benefits of SC and BPM on depression. The combination of the MBI and SG components also synergistically improved social support. Integrating MBI with SC, SG, or BPM components was an effective multicomponent approach to support caregivers in this study, although ongoing support was needed to mitigate potential short-term risks. Further research is required to validate the efficacy of this optimized intervention package. TRIAL REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR2300071235.