Social support and mental health
Social support has been described as “support accessible to an individual through social ties to other individuals, groups, and the larger community” . Although social support can be measured in many ways, perceived social support is the most commonly measured index of social support , given its ease of measurement and evidence that it is a better predictor of mental health than other measures [5, 6]. A wealth of research has demonstrated the protective effect of perceived social support on mental health in stressful situations [7,8,9]. Besides, received social support (a receipt of supportive behaviors) is also an important sub-construct of social support . Although the distinction between perceived social support and received social support exists, from the perspective of the stress and coping on social support , it is believed that the relationship between perceived and received social support should be relatively high, especially when the support demand matches the type of support provided . Similarly, some authors suggest that perceived support can be assessed through the recall of supportive behaviors provided . We believed that during the COVID-19 pandemic, an individual’s need for support matches the type of support provided, therefore, we measured social support individuals received to reflect the social support individual perceived.
It has been suggested that social support and social support resources should be viewed as related but distinct concepts . Perceived support represents one’s subjective perceptions of the extent to which social network members are available to provide social support . Several studies  have concluded that perceived quality of support is more strongly associated with mental health than with the actual structure of personal networks. Generally, perceived social support can come from a variety of sources, including, but not limited to, family, friends, romantic partners, pets, community ties, and coworkers. A wealth of research has demonstrated that different sources of social support have different influences on mental health in youth [17,18,19]. Specifically, social support from family, but not from friends was related to posttraumatic stress disorder and depression symptoms . And peer social support had a stronger protective effect against psychological distress than did family social support in another study . Sources of support can be natural (e.g., family and friends) or more formal (e.g., mental health specialists or community organizations), and it is necessary to consider the different sources of social support when exploring the relationship between social support and mental health .
The different sources of social support will co-exist within persons, and combine to form different configural profiles. The traditional method, such as variable-centered methods, may overlook differences in social support among heterogeneous groups of individuals. Although there are many papers on sources of social support that have relied on the variable-centered methods. New methods (e.g. Latent profile analysis, LPA) have received growing interest in the typologies of social support networks in recent years (e.g. [21, 22]). What’s more, although based on slightly different concepts, some researchers have used cluster analysis to study social network typologies for a long time (e.g. ). More importantly, the existing papers demonstrated different support profiles would be differently associated with mental health outcomes [21, 22, 24]. Specifically, Burholt et al.  adopted LPA and found that the four social support profiles differ in their relationships to wellbeing in older migrants. The migrants with family-oriented profiles will experience lower levels of loneliness. Lau et al.  found that as compared with participants in the family-dependent social support profile, older adults in the locally integrated social support profile were negatively associated with dementia. McConnell et al.  adopted cluster analysis and explored how the combinations of different sources of support impact mental health among lesbian, gay, bisexual, and transgender youth. Researchers found that social support profiles showed different patterns of association with mental health outcomes. Individuals with the high support profile being the least lonely; youth low in all sources of social support are the most vulnerable for hopelessness and anxiety; social support from peers and significant others—even in the absence of family support—play an important protective role in hopelessness and anxiety .
Compared to the traditional clustering method, LPA is more reasonable to test the results of individual clustering by directly estimating the membership probability from the model ([25, 26]). Specifically, LPA is a person-centered method that identifies subgroups of individuals who share common social support patterns . Besides, the outcome variables can be incorporated into the LPA model to build a regression mixture model to verify the relationship between profiles and outcomes. Hence, we conducted an LPA to explore the profiles of sources of social support and adopted the regression mixture model (BCH method) to explore the relationship between social support profiles and mental health in this study.
Unlike other crises or disasters (e.g., earthquake, economic crisis), a wider range of people will face a series of stressful events due to the pandemic itself and the related quarantine measures; therefore, the support provided both within the micro context (e.g., spouse, family, friends) and macro context (e.g., community, institutions/organizations, or even society as a whole) is vital to help ease psychological burdens. Accordingly, along with family support, it is also essential to consider the role of other sources of social support in mental health within a broader context. Furthermore, it is important to acknowledge individuals may experience different relative levels of these forms of support (e.g., high levels of support from community or even society as a whole, but low levels of family support) during the COVID-19 pandemic. However, little is known about how combinations of different sources of social support impact mental health during this period. Since individuals will face a series of stressful events during the COVID-19 pandemic, we infer that people with a high level of social support profile will experience a higher level of mental health than those with moderate or low social support profiles. Therefore, our first hypothesis is as follows:
H1a: Sources of support, including family, friends or small groups, communities, organizations/institutions, and society as a whole, positively associate with an individual’s mental health during the COVID-19 pandemic.
H1b: Individuals within different social support profiles showed different relationships with mental health during the COVID-19 pandemic. People with a high level of social support profile will experience a higher level of mental health than those with moderate or low social support profiles.
Resilience and mental health during a crisis
We can often observe that, although many people may suffer from difficulties or crises, mental health outcomes still differ among individuals, and psychological resilience is assumed to play an important role in explaining such variance. Psychological resilience can be considered as either a trait or a process/outcome . As a process, researchers referred to it as a dynamic process encompassing positive adaptation within the context of significant adversity . As a trait, resilience represents a constellation of characteristics that enable individuals to adapt to the circumstances they encounter  and resilience has a positive impact on individual mental health . A meta-analysis suggested that resilience may play a role in protecting mental health, accelerating recovery, and mitigating the negative effects of a crisis . For instance, Tugade and Fredrickson  describe resilience as a quick and effective recovery after stress, while Patel and Goodman  conceptualize resilience as preserving mental health in the face of adversity. Therefore, as a trait, psychological resilience is a key resource in helping to prevent the negative impact of a crisis. And our second hypothesis is as follows:
Interaction effect of social support and resilience on mental health
As previously noted, sources of support and psychological resilience are two resources that protect individual mental health in stressful situations. Research shows that social support is key to resilience when it is considered to be a process/outcome (e.g., [35, 36]). However, when resilience is considered to be a trait, we cannot help asking, since there are individual differences in social support and psychological resilience, could abundance in perceived social support compensate for lack of psychological resilience? One study found that sources of social support (family, friends, and others) significantly moderated the relationship between resilience and subjective well-being in college students , while another study demonstrated that the relationship between resilience and psychological distress was not moderated by social support in patients diagnosed with cancer . According to the stress-buffering hypothesis, researchers claimed that social support acted as a buffer to alleviate the negative influence of stress on well-being . Scholars found that family support played a unique role in buffering the negative effects of stress by considering the different sources of support . What’s more, Anschuetz  found that social support served to attenuate the negative effects of various trait vulnerabilities (such as neuroticism and introversion). Based on the stress-buffering hypothesis, we claim that social support from different sources can also buffer the negative effect of low levels of resilience (a trait vulnerability) on mental health, especially in a brand-new context, such as the COVID-19 pandemic. Since we adopt LPA to identify the profiles of the sources of social support, we extend the compensation hypothesis to social support profiles. Hence, our third hypothesis is as follows:
Sources of social support, psychological resilience, and mental health, varied across life stages
As a global public health emergency, the COVID-19 pandemic has caused great suffering to all people living in affected areas. When considering individual mental health as well as protective factors during the COVID-19 pandemic, age is a significant and unavoidable issue. First, many studies have shown that emotional well-being often increases across the entire adult life stage; thus, with age, people’s emotions and well-being tend to remain stable or even improve. Researchers refer to this phenomenon as the “paradox of aging” . Moreover, according to the latest data reported in Nature Medicine, compared to those aged 30–59 years, those aged below 30 and above 59 years were 0.6 and 5.1 times more likely to die, respectively, after developing symptoms of COVID-19  . Hence, older adults may experience more stress than other age groups. Therefore, the question remains as to whether the paradox of aging still exists within the context of the COVID-19 pandemic. However, according to the paradox of aging , we hypothesize that:
Second, according to socioemotional selectivity theory (SST), as individuals become more aware of time limitations in life as they age, they are more likely to spend time with emotionally close relationships than young people are [42,43,44,45]. SST also suggests that, with age, individuals narrow the size of their social network and focus on a smaller circle of friends and relatives [42,43,44,45]. Researchers found that older adults have a greater proportion of close social partners and fewer peripheral partners in their networks compared to younger adults [46, 47]. Within social support research, Potts  found that the older adults received different levels of social support from within and outside the retirement community because of the different levels of social network quantity between the within and outside the retirement community. Thus, for individuals of different ages, in terms of differences in their social networks, it is expected that the levels of sources of social support they received are different. Furthermore, a meta-analysis that systematically reviewed the characteristics of social support (types and sources) associated with protection from depression across life stages (e.g., childhood and adolescence, adulthood, older age), found that sources of support varied across life stages, with parental support being the most important among children and adolescents, whereas adults and older adults relied more on spouses, followed by family and then friends . Hence, it is worth exploring whether when everyone is under a situation in which people cannot avoid being involved, such as the COVID-19 pandemic, if there are age differences in perceived sources of social support. Therefore, according to SST, we hypothesize that:
Third, research suggests that psychological resilience may vary according to age . A survey based on a large cross-sectional Japanese sample demonstrated that psychological resilience could increase from the young adult stage to the older adult stage . Furthermore, research showed that cancer patients with higher resilience, particularly older patients, experienced lower psychological distress, indicating that the relationship between resilience and psychological distress is moderated by age . Research also demonstrated that age moderated the relationship between sources of social support and mental health, indicating that family social support is associated with lower symptoms of posttraumatic stress disorder and depression in participants aged 16–19 years, while friend social support is associated with lower symptoms for participants over 20 years old . The possible role of age was examined in these analyses, especially the age differences in associations between resilience and mental health , and the moderating role of age between sources of support and mental health . As previously noted, according to the stress-buffering hypothesis , people with a higher level of social support profile may buffer the negative effect of low levels of resilience on mental health. Few studies have examined whether the buffering effects of social support profiles vary by age, but the role of age has been associated with the variables of interest. What’s more, according to SST, older groups will have a greater proportion of high family-based support profile than the other age groups. Therefore, we hypothesize that the buffering effect between the high family-based support profile and resilience is greater in older adults: