The main objective of this study is to develop and identify an effective two-stage adaptive intervention for reducing loneliness among older Hong Kong Chinese adults involving behavioral activation and mindfulness meditation.

Our previous study showed that approximately 45% of Hong Kong Chinese older adults report that they feel lonely sometimes or always. It is well established that loneliness is associated with numerous detrimental consequences on psychological, physical, and cognitive health. Against this backdrop, it is of the utmost importance to develop an effective intervention to reduce loneliness among Hong Kong’s older adults, especially during times like the COVID-19 pandemic. The main objective of this study is to develop and identify an effective two-stage adaptive intervention for reducing loneliness among older Hong Kong Chinese adults involving behavioral activation and mindfulness meditation. Using a sequential multiple randomized trial (SMART), we aim to  

1. evaluate whether a telephone-delivered behavioral activation (Tele-BA) intervention or a telephone-delivered mindfulness (Tele-MF) intervention is a more effective first-stage intervention in terms of reducing loneliness;  
2. evaluate whether extending the original first-stage intervention with an additional motivation component or switching to an alternative intervention is more effective in reducing loneliness when participants are not responding to the first-stage intervention;  
3. evaluate whether the Tele-BA–Tele-MF sequence (8 weeks) or the Tele-MF–Tele-BA sequence (8 weeks) is more effective in reducing loneliness; and  
4. identify which of our four embedded 8-week two-stage adaptive interventions (Tele-BA with booster for responders and Tele-BA for nonresponders; Tele-BA with a booster for responders and Tele-MF for nonresponders; Tele-MF with a booster for responders and Tele-MF for nonresponders; Tele-MF with a booster for responders and Tele-BA for nonresponders) is the most effective for reducing loneliness.  

A random sample of 244 participants aged 65 and older who feel lonely will be recruited. Response will be defined as a 50% reduction in loneliness. Participants will be assessed at baseline and at 4 weeks, 8 weeks, 5 months, and 8 months after baseline. Apart from loneliness, we will also measure stress, symptoms of depression and anxiety, and sleep quality as secondary outcomes. The findings will not only inform us whether the SMART is an efficient approach for identifying an effective adaptive intervention for reducing loneliness but also, more importantly, provide evidence to understand and refine the biopsychosocial-pathways model of loneliness on which our selection of interventions and secondary outcomes is based.