The key aim of the study is to test the efficacy of a 4-week ecological momentary intervention (EMI), as compared with the regular weekly-based intervention (control group), in reducing (1) symptoms of depression and (2) rumination in community-dwelling individuals. The efficacy of the EMI in reducing distress and improving functioning is also examined.

For both EMI and control groups, the intervention will be delivered through SMS text messages, with a link to a user-friendly and locally-adapted intervention platform designed using Qualtrics (online survey programme).

It is hypothesised that (1) those in the EMI group, as compared to the control group, will show greater reductions in (1) depressive symptoms, (2) rumination level, (3) distress, and in (4) improving functioning. These effects are hypothesised to be observed in individuals with varying levels of symptom severity.

Despite the growth of online-based interventions, there remains a lack of highly adaptive and personalised smartphone-based interventions that can be implemented in the course of everyday life.

The current study examines the effectiveness of a newly-developed smartphone-based ecological momentary intervention (EMI) in reducing symptoms of depression as well as rumination and distress.

Rumination is a common experience in individuals with major depressive disorder (MDD). These psychopathological symptoms occur in a population on a continuous spectrum, which may be especially pronounced after the community has experienced a series of highly stressful and traumatic events. On the high end of the spectrum, manifestations of symptoms may be considered to be clinical disorders, and professional intervention may be indicated. Rumination may affect prognosis and there are suggestions that interventions to reduce and modify rumination can improve outcomes. At the less severe end of the spectrum (i.e., not yet reached the threshold for disorders), rumination may be a risk factor that compromises outcomes and adjustment, one that can cause significant distress and functional impairment. Targeting rumination in both below- and above- threshold populations therefore has important research and clinical implications.

Mental Health Needs in Hong Kong The Hong Kong population has undergone a series of highly stressful events traceable since June 2019, from large-scale social unrest, to the outbreak of Coronavirus disease 2019 (COVID-19) first in January 2020 and a second wave of COVID-19 cases in March 2020. Each of these population-level events is accompanied by other related social, economic, and political consequences, all of which can result in significant psychological distress and mental health burdens especially when added up to individual-level stressors. Local studies have reported heightened depressive symptoms in relation to such population-level events in addition to personal stressful events. The rates observed are considerably higher than the average global prevalence, which marks it as particularly concerning when help-seeking is severely minimal in the general local population. It is anticipated that these rates will continue rising and would manifest with symptoms of other conditions (such as anxiety, as is already seen in China during COVID-19). Unsurprisingly, the widespread pandemic has already led researchers in many other countries to call for enhanced and novel psychological interventions.

A local online self-help initiative has recently been launched by the Department of Psychiatry of the University of Hong Kong, offered to individuals via different channels (including various social media platforms, non-governmental organisations, social and personal connections) in the form of an anonymous mental health recognition and support tool. The key aims of the tool are to provide users with a space to reflect on the ongoing events in their lives and their feelings, provide them with an individualised understanding of their current mental health conditions (MDD symptoms) and the potential contributing factors, as well as offer individualised suggestions for self-help and professional help when necessary. A high level of MDD as well as significant levels of rumination in response to the community stressors have been reported, particularly in young people. Of importance, rumination about such large-scale external events ("event-based rumination") was seen to be highly associated with MDD symptoms.

Rumination and its Consequences In the presence of significant external stressors, an excessive level of symptoms, together with rumination about the stressors or their psychological responses characterise a state described as adjustment disorder (AjD) in the International Classification of Diseases, 11th Revision (ICD-11). The presence of AjD carries an increased level of risk for transition into other clinical disorders, such as MDD. The role of rumination as a mechanism that predisposes individuals towards the development of major depressive episodes has been well studied. Researchers have shown that particular types of rumination, such as brooding (i.e., passive and judgmental comparison of current situation and an unachieved alternative outcome), are specifically responsible for the development of depression. The presence of this rumination type for people with MDD also predicted poorer outcomes. Because of its importance, interventional strategies (such as cognitive-behavioural therapy, CBT) targeting rumination have been developed and have been shown to be effective in improving mental health outcomes. Rumination-focused CBT generally involves increasing one's ability to become aware of their own (brooding) ruminations and supporting them to eventually replace them with alternative thinking habits).

Ecological Momentary Assessment and Intervention Recent years have seen the growth of a new avenue for mental health that appears highly suitable for the Hong Kong population, namely ecological momentary assessment (EMA) and ecological momentary intervention (EMI). These mobile health (mHealth) approaches offered new opportunities for mental health research, management, detection, and intervention via smartphones. In EMA, individuals can self-initiate assessments when an emotion or specific event is experienced (event-sampling), or are prompted several times a day to complete brief assessments over a number of days (time-sampling). While EMIs have been used to augment usual treatments, EMIs have also been coupled with EMA to deliver interventions based on symptoms reported in the moment. The essence of these two approaches is their abilities to be implemented in real-time and in everyday life contexts, be designed flexibly according to specific objectives, and be adapted to individual needs. Capturing prospective information on interactions between micro-level experiences and real-world contexts, as well as providing in-the-moment interventions, EMA and EMI impart benefits that cannot be achieved in traditional in-person treatments.

Importantly, increasing evidence from randomised controlled trials (RCTs) has shown EMI to be an efficacious and effective means to augment interventions in different disorders, including depression, anxiety, bipolar disorders, psychosis. Furthermore, although EMA in addition to treatment-as-usual (TAU) has shown to be more effective than TAU alone in reducing depressive symptoms in patients with MDD, the positive impact of EMI was shown to be more long-lasting in the EMI+TAU group compared with EMI+TAU, with the effects lasting for up to 3 months for EMA+TAU, and up to 6 months for EMI+TAU.

The Current Study EMI appears to be a promising approach to support individuals with distress in the Hong Kong population in reducing symptoms and ruminative thoughts. This is also possibly the only means to reach those less motivated to seek help due to stigma, as well as potential worries over in-person contacts especially after the COVID-19 outbreak.

The key aim of the study is to test the efficacy of a 4-week ecological momentary intervention (EMI), as compared with the regular weekly-based intervention (control group), in reducing (1) symptoms of depression and (2) rumination in community-dwelling individuals. The efficacy of the EMI in reducing distress and improving functioning is also examined.

It is hypothesised that (1) those in the EMI group, as compared to the control group, will show greater reductions in (1) depressive symptoms, (2) rumination level, (3) distress, and in (4) improving functioning. These effects are hypothesised to be observed in individuals with varying levels of symptom severity.

Inclusion Criteria:

• Symptoms of depression indicated by DASS-D score of 10 or above
• Aged 15 to 64 years (parental or guardian consent is required for those below 18 years)
• Possess a smartphone with access to the Internet

Exclusion Criteria:

• Significant developmental disorder, psychotic disorder, substance abuse or organic brain disorder
• Active suicidal risk
• Receiving active structured intervention or anticipating to receive such treatment (e.g., biweekly psychotherapy sessions, receiving pharmacotherapy)