Opening the black box of a multicomponent intervention for informal dementia caregivers: a randomized controlled trial using the multiphase optimization strategy (MOST)

INTERVENTION: Group 1:All Components (1‐6) 1. Dementia & caregiver education 2. Self‐care skills 3. Behavioral problems management 4. Behavioral activation 5. Mindfulness yoga 6. Social support;Group 2:Components 1‐4 1. Dementia & caregiver education 2. Self‐care skills 3. Behavioral problems management 4. Behavioral activation;Group 3:Components 1‐3 & 5 1. Dementia & caregiver education 2. Self‐care skills 3. Behavioral problems management 5. Mindfulness yoga;Group 4:Components 1‐3 & 6 1. Dementia & caregiver education 2. Self‐care skills 3. Behavioral problems management 6. Social support;Group 5:Components 1‐2 & 4‐5 1. Dementia & caregiver education 2. Self‐care skills 4. Behavioral activation 5. Mindfulness yoga;Group 6:Components 1‐2, 4 & 6 1. Dementia & caregiver education 2. Self‐care skills 4. Behavioral activation 6. Social support;Group 7:Components 1‐2 & 5‐6 1. Dementia & caregiver education 2. Self‐care skills 5. Mindfulness yoga 6. Social support;Group 8:Components 1 & 2 1. Dementia & caregiver education 2. Self‐care skills;Group 9:Components 1 & 3‐5 1. Dementia & caregiver education 3. Behavioral problems management 4. Behavioral activation 5. Mindfulness yoga;Group 10:Components 1, 3‐4 & 6 1. Dementia & caregiver education 3. Behavioral problems management 4. Behavioral activation 6. Social support;Group 11:Components 1, 3 & 5‐6 1. Dementia & caregiver education 3. Behavioral problems management 5. Mindfulness yoga 6. Social support;Group 12:Components 1 & 3 1. Dementia & caregiver education 3. Behavioral problems management ;Group 13:Components 1 & 4‐6 1. Dementia & caregiver education 4. Behavioral activation 5. Mindfulness yoga 6. Social support;Group 14:Components 1 & 4 1. Dementia & caregiver education 4. Behavioral activation;Group 15:Components 1 & 5 1. Deme CONDITION: Dementia PRIMARY OUTCOME: physical health status;stress/caregiving burden;psychological well‐being;anxiety/depressive symptoms;social support; SECONDARY OUTCOME: self care;dementia care strategies;engagement in pleasurable activities;mindfulness attention awareness;satisfaction with support group; INCLUSION CRITERIA: 1. Chinese citizens aged 18 years or above; 2. Spouse, adult children or daughter‐in‐law of the person being cared for; 3. No cognitive dysfunction (MMSE score >=23); 4. Primary family caregiver for the person with dementia (at least 20 hours per week), and they have served in this role for at least one year. People are considered care providers if they help people with dementia with daily living and activities of daily living; 5. Caregivers experienced at least some depressive symptoms or feelings of burden (CES‐D > 12 or Zarit Burden Scale > 18).