The study has two phases: the co-design of the content of the intervention (phase 1) and the randomized controlled trial phase (phase 2). The setting and the participants' eligibility criteria are the same for the two phases.
Phase 1 Design: a qualitative study will be conducted on 20 caregivers of patients with dementia to identify what information they most require.
Method: 20 face-to-face interviews will be held and guided by a trained geriatrician, in a private room in the geriatrics department. The open-ended questions are used, including "what difficulties are the participant facing in taking care of the patient with dementia?", "what information do the participant need most?". Each participant will be free to share thoughts. The interviews will be audio-recorded and fully transcribed.
Data analysis: The investigator will use inductive thematic content analysis. The eight most common issues in which the carers need providing information will be determined to shape for the intervention in phase 2.
Phase 2 Study design A parallel-group randomized controlled pilot trial will be used with equal randomization of 1:1 to test the feasibility and the acceptability of the smartphone app-based intervention. Sixty dementia carers, who meet the eligible criteria and are provided written informed consent, will be enrolled in the study and will be allocated to the intervention or usual care group.
Randomization The eligible participants will be assigned to the intervention or control group by an independent statistician, using the block randomization method (blocks of 4).
Intervention The participants in the intervention group will be added to a chat room in the Zalo app, created and managed by one investigator, which is named The Dementia Caregiver Support group. Weekly, the investigator will post one of the eight topics identified in Phase 1. Before posting the information, the investigator will ask the participants what topic they would like to read and discuss the week after by voting the answer. The posted information will be based on evidence-based resources and consulted by geriatricians, the neurologist, and the psychologist who specialize in dementia. Immediately after posting the topic, one investigator will call the participants to ensure the participants read and understand the post. The chat group monitor will also collect the questions or comments from the carers who are encouraged to share feelings or experiences with relevant questions. Then the investigator will post the answers after consulting with the experts.
Usual care: The participants in the control group will be introduced to the website Alzheimer.org to search for eligible information Procedure The characteristics of the participants (age, gender, educational level, relationship to the care recipient, time of care, etc.) and other assessments will be collected by an independent investigator, who will be blinded through the study.
Measures The participants will perform the Depression, anxiety and stress scale 21 (DASS21) questionnaire via phone call interviews. DASS21 scale contains 21 items, evaluating 3 subscales including depression, anxiety, and stress states over the past week. Higher scores indicate more severity of emotional states. Dementia understanding of the participants will be evaluated at baseline and post-intervention by a questionnaire, originating from the Northern Ireland Life and Time Survey, which was translated into Vietnamese. This questionnaire contains 7 items, for example, "dementia is a normal part of aging" or "dementia can be cured". The response options will be completed with yes/no choices. Four or fewer correct answers will be coded as low understanding, five correct answers medium understanding, and six or more answers as high understanding.
Perceived social support will be assessed using the Multidimensional Scale of Perceived Social Support (MSPSS), comprising 12 self-report items assessing the perceived support from family, friends, or significant others (eg, "There is a person who is around me when I am in need). Each item is scored from 1 (very strongly disagree) to 7 (very strongly agree), based on a 7-point Likert scale. Higher scores indicate higher degrees of perceived social support. This scale will be translated and adapted into Vietnamese.
The caregiver's perceived burden will be evaluated usingthe Zarit 4-item burden interview. Each item is scored from 0 to 4, and higher scores indicate higher levels of burden.
Outcome measurements will be assessed face-to-face at baseline and via phone calls at immediate post-intervention and 3-month follow-up post-intervention.