Study Protocol Supporting family caregivers of people with dementia and identifying an effective adaptive intervention to reduce their depressive symptoms: protocol of a sequential multiple assignment randomized trial

Abstract Background: Family caregivers of people with dementia (FG-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 behavioral 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 pre-specified 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 randomized trial (SMART) 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 behavioral activation and mindfulness practice with different sequences and dosages (e.g., 8 weeks of Behavioral Activation followed by booster sessions for responders, and 8 weeks of mindfulness practice for non-responders) will be assigned to the participants following a set of decision rules. The primary outcomes will be depressive symptoms, assessed after the second stage of the intervention. Other outcomes (e.g., positive aspect of caregiving and sleep quality) and time-points will also be assessed. The analyses will follow the intention-to-treat principle. In addition, several process indicators (e.g. engagement in meaningful activities and level of mindfulness) will also be assessed. Discussion: The traditional RCT design allows for the effectiveness of an intervention to be rigorously tested but provides limited data to develop “treatment strategies” that may involve a number of different interventions, dosages, or components. We propose using the SMART design to provide evidence of which intervention to provide initially, how to determine whether the first stage of the intervention is working or not, and which intervention to provide next if the first stage of the intervention is not working. The findings will have strong implications for the further development of psycho-social adaptive intervention in reducing the depressive symptoms among FC-of-PWD. Trial registration: ClinicalTrials.gov, NCT05634317