Changes in mental well-being in Hong Kong before and during social unrest and COVID-19

Purpose Understanding the impact of co-occurring population- and individual-level stressful events on mental well-being should inform future intervention design. This study examined the association of two population-level stressful events (social unrest and COVID-19) and personal stressors with life satisfaction in Hong Kong. Methods This study analyzed data on life satisfaction, experience of stressful life events (SLEs), rumination, and resilience, from two representative population telephone surveys conducted in 2018 (n = 1,514) and 2020 (n = 1,258). The association between life satisfaction and personal SLEs was further compared between the two samples using moderation analysis. Using data from the 2020 survey, the effect of different types of SLEs, rumination, and resilience on life satisfaction was investigated using hierarchical regression analysis. Results The study achieved a response rate of 56.2% and 68.9% for surveys 2018 and 2020, respectively. Life satisfaction of the population decreased signicantly in 2020, accompanied by an overall increase in SLEs. Moderation analysis revealed that the relationship between personal SLEs and life satisfaction was signicantly greater in 2018 than in 2020. Hierarchical regression analysis showed that an increase in all kinds of SLEs and higher levels of rumination were signicantly associated with lower life satisfaction in 2020. Conclusion The signicant reduction in life satisfaction reported in this study suggests that measures to support the mental health of populations that have experienced multiple simultaneous, large-scale stressors would be crucial. During distinctive phases as such, rumination may be a potential target for improving overall mental health. by personal stressors. The observations in our study can help raise awareness in the global community to prepare for similar challenges and inform the design of future interventions.


Introduction
Large-scale stressful events, such as social con icts and public health crises, can have substantial impacts on a population's mental health [1]. Observations have been made on single events in the past.
An increasing number of societies today face multiple co-occurring population-level stressors in the same period, particularly social unrest alongside the novel coronavirus disease 2019   [2,3]. How different classes of stressful events together affect the mental health of a population as they evolve necessitates further examination.
Hong Kong people have experienced a distinctive period involving a conjunction of large-scale social unrest, which began in June 2019, and the outbreak of the novel coronavirus disease 2019  in January 2020. Marked increases in symptoms of depression and post-traumatic stress disorder (PTSD) following social unrest have been observed recently [4]. Several studies have subsequently investigated the mental health impact of COVID-19 in the general population [5][6][7][8]. However, as the complex social situation in Hong Kong evolved rapidly, from social unrest to the outbreak of COVID-19, these ndings that did not consider the co-occurring events may not fully re ect the mental health of Hong Kong people.
A recent large-scale online survey examined the combined mental health impact of social unrest and COVID-19 in addition to personal SLEs and found that the different types of stressors interacted signi cantly to increase PTSD and depressive symptoms [9].
While similar co-occurrences of population-level stressful events have been observed in other societies [10], it is unknown how the general mental well-being of the population would be affected under such complex societal conditions. It also remains to be further investigated how population-level and personallevel stressors might differently contribute to overall mental health. To ll these gaps, population-based studies that collect representative data on pre-existing mental health conditions are of crucial importance [11]. To the best of our knowledge, the current study in Hong Kong is the rst ever to report data on the general mental health of a population before and after the occurrence of multiple large-scale stress events. The availability of baseline data could facilitate the interpretation of the causal relationship between the experience of SLEs and life satisfaction.
A commonly used indicator for assessing the general mental health of the population is life satisfaction, which measures the individual's subjective sense of well-being (SWB) [12,13]. Previous research has linked life satisfaction to socio-demographic characteristics ranging from gender, income, education, and marital status [14] and SLEs [15]. While the association between depressive symptoms and life satisfaction is relatively well-studied, the pattern of the relationship necessitates further investigation [16].
In studying the relationship between SLEs and life satisfaction, rumination and resilience were cited as important factors [17,18]. Rumination was a particularly prevalent phenomenon accompanying largescale population con icts [9]. Meanwhile, resilience has been observed to be critical in addressing the negative impact on mental health during the current pandemic [19]. Signi cantly, rumination could amplify the role of resilience in its impact on mental health [20]. Extant literature suggests that the cyclical construct of rumination tends to activate, intensify, and maintain individuals' negative emotions, including low mood and anger [21,22]. Ruminators who xate on symptoms of distress experience more depressed moods than non-ruminators [21]. Sustained activation of past stressful life events through rumination may undermine individuals' post-event coping and impede recovery and be considered a risk factor for the development of PTSD [23]. However, the role of rumination and resilience in conjunction with successive large-scale stressors in the population has been minimally studied. Considering the two population-level stressors (social unrest and COVID-19) and personal stressors, the association between SLEs and life satisfaction ought to be further investigated. The current study examined the impact of two recent large-scale stressors on the life satisfaction of the Hong Kong population by comparing data from the population-based samples of 2018 and 2020. We hypothesized that the effect of personal SLEs on life satisfaction would be reduced in 2020 compared to that in 2018.
We further hypothesized that SLEs related to social unrest and COVID-19 would explain more signi cant variance in life satisfaction than personal SLEs. Other psychological factors, including rumination and resilience, would also contribute to lower life satisfaction.

Methods
We conducted two population-based telephone surveys of Hong Kong citizens between 17 January to 26 February 2018 and between 15 July to 7 August 2020. Both surveys were conducted using the Web-based Computer Assisted Telephone Interview (Web-CATI) system (supplementary material 1). They followed the American Association for Public Opinion Research (AAPOR) reporting guidelines. All respondents provided verbal consent as approved by the Institutional Review Board and Ethics Committees.

Study population
All interviews were conducted anonymously. Inclusion criteria of both surveys were adult Hong Kong residents (18 years or older), able to speak Cantonese, and able to give verbal consent. The target sample was divided into 10 gender-age strata to ensure the sample characteristics were similar to those of the general population [24].

Survey instrument and Measures
Both surveys included questions on the respondent's demographic characteristics, including age, gender, and education level. Questions on marital status, employment status, and income were included in survey 2020 only. We use a validated single-item life satisfaction ranging from 0 -10, with 10 indicating the most excellent satisfaction [25].
We used six items extracted and regrouped from the List of Threatening Experiences [26] to assess the respondent's experience of stressful life events in the past year. The six items captured the following subtypes of SLEs: (1) family/relationship issues, (2) legal issues, (3) work/school stress, (4) nancial di culties, (5) health/injury (self), and (6) health/injury (family/close people). To further capture the impact of social unrest and COVID-19 on the population in the 2020 survey, for each of the SLEs endorsed, we asked the respondents whether this event was related to social unrest only, related to COVID-19 only, or related to both social unrest and COVID-19. Those reporting the SLE as not related to either social unrest or COVID-19 social unrest were considered as personal SLEs.
In survey 2020, we used a 4-item Patient Health Questionnaire (PHQ-4) to assess the respondent's depressive (2 items) and anxiety (2 items) symptoms in the past two weeks [27]. Respondents rated the frequency of each symptom on a 4-point Likert scale from 0 (not at all) to 3 (nearly every day). The summary score of depressive and anxiety symptoms was calculated by summing up the two corresponding items (0 -6, 6 indicating the highest level of depressive or anxiety symptoms). The PHQ-4 demonstrated high internal reliability, with a Cronbach's α of 0.83 in this study. We also assessed the respondent's experience of rumination using two items on the brooding of the Rumination Response Scale [28]. We also used a validated 2-item Connor-Davidson Resilience Scale [29]. Respondents rated each item of both scales on a 4-point Likert scale, ranging from 0 (almost never) to 4 (almost always).
The summary score of each scale was calculated by summing up the responses (0 -8, 8 indicating the highest level of rumination and resilience). In this study, the Cronbach's α of the scale of rumination and resilience was 0.77 and 0.65, respectively.

Statistical analysis
The response rate was calculated using the American Association for Public Opinion's Research Response Rate de nition [30]. Two-sided P < .05 was considered statistically signi cant. All analyses were performed with Statistical Package for the Social Sciences (SPSS), version 26.0. Weighting was applied to the dataset to adjust for any differences between the sample and the general population.
To test life satisfaction as a good indicator for general mental health, we examined the partial correlation between life satisfaction and depression and anxiety symptoms using the data of survey 2020, with age, gender, and education as controlling variables. Life satisfaction and experience of all sub-types of SLEs were compared between 2018 and 2020 using the Mann-Whitney U test (as the assumption of data normality was not met) and chi-square test, respectively. To compare the relationship between personal SLEs and life satisfaction in the 2018 and 2020 samples, a moderation analysis, with the year of the survey as a dichotomous moderator variable, was performed with PROCESS in SPSS. The model was adjusted for age, gender, and education level. A signi cant interaction effect would suggest that the relationship between personal SLEs and life satisfaction varied across the two years.
To assess SLEs and psychological factors associated with life satisfaction, we built a 6-step hierarchical multiple regression using the data from survey 2020. The outcome was life satisfaction, and covariates included gender, age, education, marital status, employment status, and income. Variables were added to the regression in the following order: (1)  Of the 2,620 SLEs reported in 2020, 751 (28.7%) were related to both social unrest and COVID-19, 209 (8%) were related to social unrest only, and 356 (13.6%) were related to COVID-19 only. The number of personal SLEs reported in 2020 (n = 1,309) was similar to that in 2018 (n = 1,331).

Effects of personal SLEs on life satisfaction in 2018 and 2020
Combining the data of survey 2018 and 2020, every 1 unit increase in personal SLEs was signi cantly associated with a 0.734 unit decrease in life satisfaction (95%CI, -0.918 to -0.551, P < .001). From 2018 to 2020, life satisfaction decreased signi cantly by 1.030 units (95%CI, -1.204 to -0.856, P < .001). The signi cant interaction effect revealed in the moderation analysis indicated that the association between personal SLEs and life satisfaction signi cantly varied across the two surveys (P < .001) ( Table 2).
Effects of personal and external SLEs, rumination, and resilience on life satisfaction in 2020 Results of the hierarchical regression analyses are presented in Table 3. After controlling for demographic characteristics, more experiences of SLEs (b = -0.095 to -0.800), higher levels of rumination (b = -0.164) were signi cantly associated with reductions in life satisfaction. In the rst step, demographics characteristics explained 4.6% of the variance in life satisfaction. In step two, personal SLEs further explained 0.3% of the variance. In steps three and four, SLEs related to social unrest only, and COVID-19 only further explained 5.8% and 3.1% of the variance in life satisfaction. In step ve, SLEs related to both social unrest and COVID-19 explained an additional variance of 9.4%. In the last step, rumination and resilience added 2.4% of the variance in life satisfaction.

Conclusion
Our ndings revealed a signi cant decline in the general mental health of the Hong Kong population as indexed by life satisfaction. Life satisfaction was negatively associated with the experience of SLEs in both 2018 and 2020. Importantly, we found that the experiences of SLEs signi cantly increased in 2020, with over half of the SLEs reported being related to either social unrest or COVID-19.
To our knowledge, this was one of the rst population-based studies that compared the general mental health of a population before and after a protracted period of co-occurring social unrest and COVID-19. It may be noteworthy to further consider the comparison of life satisfaction and reported SLEs between 2018 and 2020. Our regression model showed that, in 2020, personal SLEs contributed relatively less to general mental health, while external SLEs, i.e., stressors affecting the entire population, including social unrest and COVID-19, contributed more. Overall, recent encounters with SLEs have signi cantly predicted general mental health in 2018 and 2020. The interaction analysis also revealed that the effect of personal SLEs on life satisfaction shifted signi cantly from 2018 to 2020. When two additional large-scale stressors were taken into account, the personal SLEs were less predictive of life satisfaction.
To date, there is limited information on how SLEs on personal and community levels may differentially impact the general mental health of the population. Existing studies have shown some inconsistencies in the ndings, where some researchers found that personal SLEs were more strongly associated with subjective mental health than socioeconomic stressors [32], while others also suggested a mediating role of sense of control in the relationship between SLEs and general mental health in older Chinese adults [33]. Future studies may further investigate how the sense of control affects the relationship between SLEs and general mental health in a population.
Our ndings supported the rst two hypotheses that general mental health deteriorated from 2018 to 2020 and that SLEs associated with social unrest or COVID-19 had a signi cant impact on the worsening trend. The ndings on the relationship between SLEs and life satisfaction were consistent with previous ndings [15]. This study additionally suggested that SLEs related to social unrest and COVID-19 had a more signi cant impact on life satisfaction. Therefore, the future design of mental health interventions should consider targeting people who experienced more SLEs related to social unrest and COVID-19.
Results of this study about the relationship between rumination and general mental health are consistent with previous ndings [34,35]. While past research suggested that general mental health can be explained by rumination [36], the current research put forward rumination as a prominent predictor of life satisfaction.

Strengths & limitations
The study allowed investigation on changes in the general mental health of the population in two representative samples in Hong Kong from 2018 to 2020. Considering the two large-scale stressors, i.e., social unrest and COVID-19 pandemic, could provide important insights into factors contributing to population mental health. These ndings would be of global relevance given the increasing number of countries facing the pandemic and mass social movements simultaneously (e.g., the USA, France, Thailand, South Africa) [3].
Meanwhile, several limitations of the study should be noted. First, the validity of using life satisfaction as an index of general mental health is controversial in the literature due to its subjective nature [37,38]. However, as the World Health Organization has recently de ned life satisfaction as a core part of good mental health [39], we believe that our study has generated valuable ndings on the population mental health of Hong Kong. Second, the mental health status of the population could only be measured from a subjective perspective, but not more objectively, because the study collected data by telephone interview. Third, the sampling method for households using xed telephones may also have limited the generalizability of our results [15]. Nonetheless, this method also has the advantages of reaching geographically dispersed samples and collecting data from those who may not be willing to participate in person [40], especially during COVID-19 and social unrest. Since data were collected from two distinct samples over two time points, we reported overall changes in trends in population mental health instead of changes within subjects. We would caution against interpreting the study as a prospective investigation of the mental health conditions of a population-based sample over two years.
In summary, we have shown that the general mental health of the Hong Kong population declined signi cantly in 2020 compared to 2018. Notably, large-scale external events, including social unrest and COVID-19, have contributed signi cantly to the decline in population mental health in addition to other personal stressors. Supportive measures are vital to protect the mental health of Hong Kong people. We suggest that psychoeducation on the concept of rumination is vital during this distinctive phase in Hong Kong.

Declarations
Funding The current study was funded by the Hong Kong Jockey Club Charities Trust as part of the Jockey Club Mental Wellness Project for Women.
Con ict of interest The authors declare that they have no con ict of interest.
Availability of data and material The data generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Code availability Not available
Authours' contributions WMYS, SLTT, CKWS, HLMC, SYN, and CYHE are responsible for study conceptualization and design. MYS, SLTT, SYN, and CYHE are responsible for data analysis and interpretation. WMYS, SLTT, and SYN were responsible for manuscript drafting. All authors were involved in the critical revision of the manuscript for important intellectual content. SYN had full access to all data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.   Step 1 Step 2 Step 3 Step 4 Step 5 Step   Note. *** p < .001, ** p < .01, * p < .05. b = unstandardised regression coefficient; CI = confidence interval. Figure 1 The mean (SD) score for life satisfaction signi cantly declined from 7.03 (1.82) in 2018 to 6.37 (2.12) in 2020 (P < .001). All sub-types of SLEs also showed signi cant increases from 2018 to 2020

Supplementary Files
This is a list of supplementary les associated with this preprint. Click to download. sm120210417.docx