Sequential multiple assignment randomised controlled trial protocol for developing an adaptive intervention to improve depressive symptoms among family caregivers of people with dementia.

OBJECTIVES: Family caregivers of people with dementia (FC-of-PWD) suffer from a high level of stress and depressive symptoms, which usually require different interventions at different stages. Although some standalone interventions such as behavioural activation (BA) and mindfulness practice (MP) have been shown to be potentially effective at reducing depressive symptoms, the best sequence and combination of these interventions for caregivers are unknown. This study aims to develop and identify a two-stage adaptive intervention with prespecified rules guiding whether, how or when to offer different interventions initially/over time to reduce depressive symptoms in FG-of-PWD.

METHODS: A sequential multiple assignment randomised trial design will be adopted. 272 FG-of-PWD with mild to moderate depressive symptoms will be recruited from the community. Four two-stage, embedded adaptive interventions involving BA and MP of different sequences and dosages (eg, 8 weeks of BA followed by booster sessions for responders and 8 weeks of MP for non-responders) will be assigned to the participants following a set of decision rules. The primary outcomes will be depressive symptoms (measured using the Patient Health Questionnaire-9), assessed after the second stage of the intervention. Other outcomes, such as positive aspects of caregiving (measured using the Positive Aspects of Caregiving Scale), sleep quality (measured using the Pittsburgh Sleep Quality Index) and time points will also be assessed. The analyses will follow the intention-to-treat principle. Several process indicators (eg, engagement in meaningful activities and level of mindfulness) will also be assessed. The findings will have strong implications for the further development of psychosocial adaptive interventions to reduce depressive symptoms among FC-of-PWD.

ETHICS AND DISSEMINATION: This study has received ethical approval from the Human Research Ethics Committee at The Hong Kong Polytechnic University (HSEARS20211223001). The findings will be presented at academic conferences and submitted to peer-reviewed journals for publication.

TRIAL REGISTRATION NUMBER: NCT05634317.