According to the MacArthur’s theory (Rowe and Kahn, 2015; Jang and Kim, 2021), successful aging encompasses three principal components: low risk of disease and disease-related disability, maintenance of high mental and physical function, and continued engagement with life, which includes relations with others and productive activity. It has been demonstrated that interpersonal relationships are closely related to the experiences of aging for older adults (Shiovitz-Ezra and Litwin, 2012; Ye and Zhang, 2021). Due to the changes of social status and functional limitations, older people are more vulnerable to social isolation and relationship breakdown than others (Stoeckel and Litwin, 2016). It is of great importance to pay attention to older adults’ interpersonal needs, which reflect their sense of self-worth and belongingness. According to the finding by Van Orden et al. (2010), interpersonal needs consist of two related but independent components: thwarted belongingness and perceived burdensomeness. Thwarted belongingness is a lack of social relationships, which is accompanied by loneliness. Perceived burdensomeness is the thought that one is a burden upon one’s loved ones and is accompanied by self-hatred. Insufficient interpersonal needs may make individuals feel pain due to lack of connection with others, thereby resulting in non-adaptive behaviors (Kwon et al., 2020). Widely recognized by researchers, a high degree of frustration of interpersonal needs is considered to be an important indicator for suicide ideation (Park and Kim, 2019; Kyron et al., 2021).

However, few studies to date have directly examined the relationship between interpersonal needs and successful aging. Nevertheless, the link between interpersonal needs and the living quality of aging people was also evidenced. A recent study on community-dwelling older adults showed that interpersonal needs had a great impact on attitude toward aging (Jang and Kim, 2021). A sense of belongingness helps individuals to express their identity, promote emotional well-being in their relationships, and enhance physical and mental health (Shields, 2008). On the contrary, low senses of belonging and perceived psychological or emotional burdens are considered to be risk factors of mortality in older adults due to psychological problems such as loneliness, hopelessness, and depression (Van Orden et al., 2012). Previous studies found that older adults scored significantly higher on thwarted belongingness than on perceived burdensomeness assessed by the Likert scale (Eades et al., 2019; Kinory et al., 2020). This indicated that thwarted belongingness is a more common psychological experience than perceived burdensomeness for most older adults. Accordingly, only thwarted belongingness was examined in this study. We speculate that thwarted belongingness would influence older adults’ positive mental health, and further affect quality of aging (i.e., successful aging). In this study, the impact of positive feelings and positive functioning of older adults on successful aging was examined. Therefore, the term of “positive mental health” proposed by Keyes (2002) was used.

As a cognitive coping resource, meaning in life is an important protective factor when people face major setbacks (Zhong et al., 2019; Yu et al., 2021). Meaning in life refers to an innate drive to find meaning and significance in individuals’ lives (Steger et al., 2006). Ego integrity is the core issue that a person faces in his/her late life (Erikson, 1982). Bueno-Pacheco et al. (2021) demonstrated that trying to find meaning and reconciling life events can facilitate the achievement of ego integrity. Finding and maintaining meaning and purpose in one’s life (i.e., meaning in life) has been demonstrated to play an important role in the relationship between stressful events and mental health. Researchers revealed that interventions aimed at increasing meaning and purpose in life can improve individuals’ health and well-being in older adults (Gellis et al., 2020). An empirical study on 588 older adults showed that higher levels of meaning and goal could buffer the impacts of interpersonal stressful events on depressive symptoms and life satisfaction (Lee et al., 2022). Conversely, reduced meaning in life was found to be a crucial predictor to the feeling of loneliness (Macià et al., 2021). Accordingly, we hypothesized that meaning in life would moderate the relationship between thwarted belongingness, positive mental health, and successful aging in older adults, which will be tested in the current study.

To date, the most widely used self-report instrument to assess the meaning of life is the Meaning in Life Questionnaire (MLQ) developed by Steger et al. (2006). It has two factors: presence of meaning (MLQ_P) and search for meaning (MLQ_S). Previous studies hold generally consistent viewpoints on the effect of MLQ_P and addressed its importance in facilitating mental health, promoting life functioning, and reducing emotional distresses (Steger et al., 2009; Yang et al., 2019). By contrast, the impact of MLQ_S on mental health outcomes is controversial. Some researchers asserted that search for meaning is painful, which is usually positively correlated with depression, anxiety, depression, and negative self-concept (Steger et al., 2006). Search for meaning may lead to increased depression and anxiety as well as a stronger sense of loss in the late life (Davis et al., 2000). However, several studies in Eastern countries found that the relationship between search for meaning and mental health outcomes was non-significant or even positive (Liu and Gan, 2010; Jin et al., 2016; Yang et al., 2019).

This phenomenon may be due to culture difference. Steger et al. (2008) found people in Eastern countries usually hold a dialectical way of thought, and regard the continuous process of searching for meaning as essential to acquire desired outcomes. Therefore, in our study, the moderating roles of MLQ_P and MLQ_S were tested, respectively. We speculate that both of these two components act as beneficial factors in facilitating older adults’ mental health outcomes in the Chinese context.

Due to gaps in these existing literature (i.e., little research with older adults about thwarted belongingness, positive mental health, meaning in life, and successful aging), the current study sought to clarify how and under what conditions thwarted belongingness links to successful aging, and also test the roles of positive mental health and meaning in life among Chinese older adults. Based on the MacArthur’s theory and existing evidence, a framework was developed in the current study (see Figure 1). The specific hypotheses were as follows:

The investigation was conducted from February to October, 2021. Authorization for the data collection was obtained from the Ethics Committee of Sichuan International Studies University. The inclusion criteria of participants in this study were (1) aged between 60 and 75; (2) living in communities rather than nursing institutions; (3) no history of serious psychiatric or neurological illness; and (4) no evidence of substance abuse or dependence in the past 3 months. Through flyers and advertisements, a total of 362 older adults were recruited from 4 communities in Chongqing, China. Before investigation, the inclusion criteria and the study goals were explained to all participants. After signing the written informed consent, all participants completed self-reported measures of background information, thwarted belongingness, successful aging, meaning in life, and positive mental health. For the participants who could not read or understand questionnaires independently, the investigators read questions one by one and helped them fill in the questionnaires. After excluding 23 incompletely filled questionnaires, a total of 339 valid questionnaires were obtained. The final samples consisted of 133 males and 206 females. The mean age of valid participants was 65.32 (SD = 3.43). Table 1 provides the demographic characteristics of older adults in the current study.

According to Podsakoff et al.’s (2003) suggestions, Harman’s one-factor test was adopted to test the potential common method biases for all research items. Nine distinct factors with eigenvalue greater than 1 were obtained, with the largest factor accounting for 34.94% of the variance (<40%, the threshold level). Therefore, the common method variance was limited in the current study. Descriptive analyses were used to describe the values of study variables. Independent sample t-test and one-way ANOVA were performed to test the effects of gender and marital status on successful aging. Pearson correlation analyses were conducted to explore the associations of study variables. Hierarchical linear regression analyses were used to examine whether positive mental health mediated the link of thwarted belongingness and successful aging in older adults. PROCESS macro for SPSS with bootstrapping (Hayes, 2017) was performed to examine the moderating roles of MLQ_P and MLQ_P in the relationship between thwarted belongingness, positive mental health, and successful aging. Considering the significant correlations with successful aging, education level and physical health were controlled as covariates in the statistical analyses. All continuous variables were centered before testing the hypothesized moderated mediation model. SPSS 26.0 was used for data analyses in the current study.

Means, standard deviations, and possible ranges were calculated for main study variables in the current study. Independent sample t-test was performed and the results showed that no gender difference was found in successful aging between men and women (52.73 ± 12.15 vs 51.78 ± 12.06, t = 0.70, p = 0.482 > 0.05). One-way ANOVA showed that the effect of marital status on successful aging did not reach statistical significance [F_(2,336) = 1.354, p = 0.260 > 0.05]. A series of Pearson correlation analyses were conducted to explore possible associations among main study variables. Results in Table 2 showed that there was no significant relationship between age, economic status, and successful aging (ps > 0.05). However, successful aging was found to be related to higher levels of education (r = 0.26, p < 0.001) and better physical health (r = 0.25, p < 0.001). As predicted, successful aging was negatively related to thwarted belongingness (r = −0.52, p < 0.001) and positively related to MLQ_P, MLQ_S, and positive mental health (r = 0.57–0.83, ps < 0.001). Accordingly, the initial Hypothesis 1 was well supported.

Hierarchical linear regression analyses were used to test whether positive mental health served as a mediator in the link of thwarted belongingness and successful aging. Model 1 regressed positive mental health on thwarted belongingness after controlling for education level and physical health. Model 2 regressed successful aging on thwarted belongingness with education level and physical health as covariates. The results indicated that thwarted belongingness had a significant negative influence on older adults’ positive mental health (β = −0.52, t = −11.43, p < 0.001) and successful aging (β = −0.46, t = −9.75, p < 0.001). Model 3 regressed successful aging on thwarted belongingness and positive mental health after controlling for education level and physical health. Our results revealed that thwarted belongingness did not significantly predict successful aging (β = −0.05, t = −1.46, p = 0.146 > 0.05) after positive mental health was entered into the regression model, while positive mental health exhibited a positive impact on successful aging (β = 0.78, t = 20.98, p < 0.001). The mediation model can explain 70.2% of successful aging variance. Accordingly, positive mental health totally mediated the effect of thwarted belongingness on successful aging. Therefore, our initial Hypothesis 2 was supported.

Hayes’s (2017) PROCESS macro with Model 59 was applied to test whether presence of life (MLQ_P) could moderate the relationships between thwarted belongingness, positive mental health, and successful aging. As shown in Table 3, after controlling for education level and physical health, thwarted belongingness negatively predicted positive mental health (b = −0.67, t = −8.20, p < 0.001), and this effect was moderated by MLQ_P (b = 0.04, t = 3.39, p < 0.001). Consistent with the results of the above mediation model, thwarted belongingness could not directly predict successful aging (b = −0.11, t = −1.65, p = 0.099 > 0.05), while positive mental health positively predicted successful aging (b = 0.69, t = 19.09, p < 0.001). In addition, the link between positive mental health and successful aging was moderated by MLQ_P (b = 0.02, t = 2.14, p = 0.001 < 0.05). Therefore, MLQ_P served as a mediator in the relationship between thwarted belongingness and positive mental health (the first stage of the mediating effect) as well as the relationship between positive mental health and successful aging (the second stage of the mediating effect).

Furthermore, the conditional indirect effect analysis showed that the indirect effect of thwarted belongingness on successful aging via positive mental health was moderated by MLQ_P (Table 3). For older adults with low levels of MLQ_P, thwarted belongingness exhibited a negative impact on successful aging through decreased positive mental health (b = −0.52, p < 0.001). For older adults with high levels of MLQ_P, this indirect effect remained significant, but to a weaker degree (b = −0.37, p < 0.001).

According to Holmbeck’s (2002) guidelines, we examined simple slopes at 1 SD above and below the mean MLQ_P level to test the significant effect of the MLQ_P × thwarted belongingness interaction on positive mental health. As shown in Figure 2A, at low levels of MLQ_P (<18.82), thwarted belongingness exhibited a significant and negative impact on positive mental health (β = −0.51, t = −7.74, p < 0.001). At high levels of MLQ_P (>27.76), thwarted belongingness could also significantly predict positive mental health (β = −0.29, t = −5.60, p < 0.001). These results indicated that thwarted belongingness had a stronger impact on positive mental health for older adults having lower levels of present of meaning, compared with those reporting higher levels of present of meaning. To illustrate the moderating effect of MLQ_P in the relationship between positive mental health and successful aging, another simple slope test was performed. As shown in Figure 2B, at low levels of MLQ_P, positive mental health exhibited a significant and positive impact on successful aging (β = 0.64, t = 12.13, p < 0.001). At high levels of MLQ_P, positive mental health could also significantly successful aging (β = 0.81, t = 14.36, p < 0.001). The results revealed that the effect of positive mental health on successful aging was weaker for older adults with lower levels of present of meaning, as compared to those who had higher levels of present of meaning.

The same procedure was performed to test the moderating role of search for meaning (MLQ_S). As shown in Table 4, thwarted belongingness could negatively predict positive mental health (b = −0.61, t = −8.80, p < 0.001), and this effect was moderated by MLQ_S (b = 0.03, t = 3.04, p = 0.003 < 0.01). Thwarted belongingness could not directly predict successful aging (b = −0.08, t = −1.46, p = 0.146 < 0.001). Successful aging could be positively predicted by positive mental health (b = 0.63, t = 15.97, p < 0.001) and this effect was moderated by MLQ_S (b = 0.013, t = 1.23, p = 0.034 < 0.05). These results indicated that MLQ_S moderated the relationship between thwarted belongingness and positive mental health (the first stage of the mediating effect) and it also moderated the relationship between positive mental health and successful aging (the second stage of the mediating effect).

Furthermore, the conditional indirect effect analysis showed that the indirect effect of thwarted belongingness on successful aging via positive mental health was moderated by MLQ_S (Table 4). For older adults with low levels of MLQ_S, thwarted belongingness exhibited a negative impact on successful aging through decreased positive mental health (b = −0.44, p < 0.001), although this indirect effect was still significant but became weaker (b = −0.30, p < 0.001) for older adults with high levels of MLQ_P.

The simple slope tests shown in Figure 2C revealed that when low MLQ_S was reported by older adults, the linkage of thwarted belongingness and positive mental health was significant (β = −0.46, t = −8.75, p < 0.001). When MLQ_S was high, thwarted belongingness could also predict positive mental health but became weaker (β = −0.25, t = −4.30, p < 0.001). As illustrated in Figure 2D, the relationship between positive mental health and successful aging was weaker (β = 0.59, t = 11.44, p < 0.001) for participants reporting lower levels of MLQ_S, compared to those reporting higher levels of MLQ_S (β = 0.75, t = 12.79, p < 0.001).

Together, the above results substantiated our Hypothesis 3 that MLQ_P and MLQ_S serve as beneficial factors and moderate the pattern of relationships between thwarted belongingness, positive mental health, and successful aging.

Some limitations of this study should be noted. Firstly, due to the cross-sectional design, the causal relationship of main study variables should be further confirmed in future studies. Secondly, older adults with 60–75 years old were recruited in our study. They still have better psychical and mental functions to find new goals and values of life. Therefore, these conclusions in our study can not be applied to people who aged above 75 years old. Meanwhile, the limited age range of older adults in this study prevented us from clarifying the relationship between age and successful aging. Thirdly, the sample of 339 older adults is indeed a small one which may limit the generalization of the results. The findings in the current study need to be further verified in larger samples. Finally, there might be sampling bias in this study. It is hardly accessible to recruit those who have more serious social isolation and thwarted belongingness due to severe physical limitations.