The goal of this randomized controlled trial is to test whether executive attention unpacks the antidepressant effect of Baduanjin (a form of health qigong) in older adults.

The main questions it aims to answer are:

• Is Baduanjin an effective treatment to enhance executive attention in older adults with depressive symptoms?
• Does Baduanjin work through enhanced executive attention to alleviate depressive symptoms in older adults? Researchers will compare Baduanjin with waitlist control. Participants will receive 12-week Baduanjin training (two sessions per week and 60 min per session).

Baduanjin is a type of health qigong that has been shown to effectively reduce depressive symptoms in older adults. However, the cognitive mechanism that explains such antidepressant effect remains unclear. Executive attention represents the cognitive processing that deals with interference and conflict, and it is likely to be a mechanism to unpack Baduanjin's treatment effect on depressive symptoms. There is also a lack of understanding of Badunajin's effects on brain activation in depressed older adults. To address these knowledge gaps, we propose a fully powered randomized controlled trial (RCT) with 198 older adults with at least mild depressive symptoms. They will be randomly assigned to either the active intervention group (12-week Baduanjin training) or the waitlist control group. The primary outcome is executive attention. Secondary outcomes include depressive symptoms, amplitudes of N2 and P3 components (i.e., components of event-related potentials in brain) during attention tasks, and alerting and orienting networks of attention. These outcomes will be assessed at baseline and post-intervention (12 weeks after baseline). Repeated measures ANOVA will be used to test for treatment effects on the primary outcome. Executive attention's mediation effect on the linkage between group (intervention vs waitlist control) and depressive symptoms will be tested with SPSS Macro PROCESS. The Baduanjin-related enhancement in N2 amplitude, P3 amplitude, alerting, and orienting will be explored with repeated measures ANOVA, respectively. Correlation analyses will be used to evaluate the association (i) between changes in N2 and P3 amplitudes and changes in executive attention and (ii) between changes in N2 and P3 amplitudes and changes in depressive symptoms.

Inclusion Criteria:

• have mild or severer levels of depressive symptoms, as indicated by Geriatric Depression Scale scores of 5 or above or Depression Anxiety and Stress Scale-21 depression subscale scores of 4 or above
• self-identified as physically stable and without life-threatening diseases
• be able to communicate in Cantonese or Mandarin.

Exclusion Criteria:

• (have a history of practicing or receiving training in any form of mind-body or regular exercises (including tai chi, yoga, and qigong or regular physical activity > 3 times/week) during the month prior to recruitment
• have changed medications or the dose of medications prescribed for their health condition in the month prior to study enrollment
• have a severe cognitive or language impairment, as indicated by a score of less than 21 on the Montreal Cognitive Assessment
• receiving pharmacological treatment, electroconvulsive therapy, psychotherapy, or psychoeducation for any psychological or psychiatric condition upon the time of recruitment
• be unable to demonstrate satisfactory standing balance.