Three versus six sessions of problem-solving training with or without boosters for care partners of adults with dementia (CaDeS): a randomised controlled optimization trial

Background: Problem-Solving Training/Descubriendo Soluciones Juntos (PST/DSJ) can improve emotional consequences of caregiving. We assessed the number of sessions and boosters needed for reducing caregiver burden and depressive symptoms among Alzheimer's disease and related dementias (ADRD) care partners. Methods: We conducted a randomised factorial-design trial of bilingual PST/DSJ among ADRD care partners (NCT04748666). Participants were randomly assigned (blocks of 8 stratified by language) to 3 PST/DSJ sessions with (n = 19) or without (n = 21) boosters or 6 PST/DSJ sessions with (n = 28) or without (n = 29) boosters. The Zarit Burden Interview measured caregiver burden and Patient Health Questionnaire (PHQ-8) measured depressive symptoms at baseline, after sessions, and after boosters. Findings: Ninety-seven care partners participated in the study (93% of those randomised) between June 2021 and July 2023 (n = 80 women, 83%). Ninety-five were included in intention-to-treat analysis (98% retention). For caregiver burden, all groups improved significantly over time (Estimate = -0.40, p = 0.004, Cohen's D = 0.31), with no difference between intervention groups. For depressive symptoms, there was a main effect of time (Estimate = -0.16, p = 0.005, Cohen's D = 0.33) indicating overall improvement regardless of group. Within group effect sizes (Cohen's D = 0.17-0.51) suggest larger improvement with 6 sessions (Cohen's D = 0.28-0.51) than 3 sessions (Cohen's D = 0.17-0.41). No adverse events occurred. Interpretation: Neither the number of sessions nor boosters resulted in differential efficacy for caregiver burden and depressive symptoms, though six sessions and boosters yielded the largest effect sizes. These results can inform the implementation of an evidence-based, bilingual problem-solving intervention to reduce burden and improve mood among diverse dementia care partners. Funding: Texas Alzheimer's Research and Care Consortium TARCC 2020-06-25-CR.