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Functional disability and depressive symptoms: longitudinal effects of activity restriction, perceived stress, and social support Shiau-Fang Chao

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Department of Social Work, National Taiwan University, Taipei, Taiwan Published online: 30 Jan 2014.

To cite this article: Shiau-Fang Chao (2014) Functional disability and depressive symptoms: longitudinal effects of activity restriction, perceived stress, and social support, Aging & Mental Health, 18:6, 767-776, DOI: 10.1080/13607863.2013.878308 To link to this article: http://dx.doi.org/10.1080/13607863.2013.878308

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Aging & Mental Health, 2014 Vol. 18, No. 6, 767–776, http://dx.doi.org/10.1080/13607863.2013.878308

Functional disability and depressive symptoms: longitudinal effects of activity restriction, perceived stress, and social support Shiau-Fang Chao* Department of Social Work, National Taiwan University, Taipei, Taiwan

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(Received 9 September 2013; accepted 12 December 2013) Objectives: This longitudinal study investigates how activity restriction, perceived stress, and social support affect the relationship between functional disability and depressive symptoms. Method: This longitudinal study of a Taiwan population analyzed a nationally representative sample of 1268 subjects aged 60 years and over. Path analysis was used to assess interrelations among functional disability, activity restriction, perceived stress, social support, and depressive symptoms over time. Results: The analytical results supported the following relationships: (a) high functional disability were associated with high activity restriction, low social support, and high perceived stress over time, (b) high functional disability, high activity restriction, low social support, and high perceived stress were associated with high levels of depressive symptoms over time, (c) among the four factors, perceived stress exerted the strongest cross-sectional and longitudinal effect on depressive symptoms, and (d) the significant effect of prior functional disability on subsequent depressive symptoms substantially contributed to indirect changes in activity restriction, perceived stress, and social support between waves. Conclusion: The findings indicate that functional disability may contribute to subsequent depressive symptoms by reducing activities and social support. Decreased activities and social support increased perceptions of stress, which then increased depressive symptoms during the 8-year follow-up study. Keywords: functional disability; activity restriction; perceived stress; social support; depressive symptoms

Introduction Being dependent is considered one of the most stressful life events in later life (Pearlin & Skaff, 1995). Studies of elderly adults in Taiwan show that health and independence are two primary indicators of successful aging (Hsu, 2007). Functional disability not only diminishes the independence of elderly individuals, it also causes ongoing challenges to managing their existing life styles, social roles, and activities (Falcon, Todorova, & Tucker, 2009). Consequently, the experience of functional disability and psychosocial adversities that come along with disability (e.g., social isolation, economic strain or relocation) usually lead to or trigger more severe symptoms of depression (Alexopoulos, 2005). In the meantime, the presence of depressive disorders can adversely prevent an individual from participating productive activities and result in increasing psychosocial impairment (Judd et al., 2008). Thus, a prevalent theme in gerontology literature is the challenges of functional disability and its impact on depressive symptomology (Gayman, Turner, & Cui, 2008; Paul, Ayis, & Ebrahim, 2006; Tsai, Yeh, & Tsao, 2005; Yang, 2006). However, older people with similar levels of functional disability may exhibit different mental health outcomes in response to the stress. Some disabled older people tend to express fewer depressive symptoms compared to their functionally impaired counterparts. Previous studies have suggested that internal (i.e., perceived stress) and external (i.e., social support) resources may moderate *Email: [email protected] Ó 2014 Taylor & Francis

or mediate the impact of stress on disabled elders’ emotional well-being (Chao, 2012; Hsu & Tung, 2010; Nemeroff, Midlarsky, & Meyer, 2010). However, relatively little information is available on how these internal and external factors are connected to exert longitudinal effects on older individuals’ psychological adjustments in response to declining physical status. Guided by the Stress Process Model (SPM), the stress process of experiencing functional disability can be divided into five major domains: (1) primary stressors; (2) secondary role strains; (3) secondary intrapsychic strains; (4) outcomes; and (5) mediators (Pearlin, 1989; Pearlin & Skaff, 1995). Primary stressors refer to the unscheduled or undesired events that occur in old age. Secondary role strains are relatively enduring problems, interpersonal conflicts or social role losses resulting from primary stressors. Secondary intrapsychic strains refer to the negative feelings elicited by primary stressors. Outcomes involve various physical and psychological indicators that are commonly used to represent well-being as manifestations of stressors. Mediators are internal or external factors that may govern the effects of stressors on outcome measures (Gignac, Cott, & Badley, 2000; Pearlin, 1989, 1992; Pearlin & Skaff, 1995; Rose, Holmbeck, Coakley, & Franks, 2004). More recently, Pearlin (2010) further emphasized that the deleterious effects of stressors can vary over time. Some adverse impacts can appear immediately after the onset of stressors, some are relatively persist and some may develop over time.

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This research aims to explore the way prior functional disability may affect depressive symptoms at follow-ups through the longitudinal influences of activity restriction, perceived stress and social support. In this study, functional disability, activity restriction, perceived stress, depressive symptoms and social support represent primary stressor, secondary role strain, secondary intrapsychic strain, outcome and mediator in the SPM, respectively. Previous cross-sectional studies have observed that functional disability is significantly related to depression in old age (e.g., Boey, 2001; Chou & Chi, 2005). However, existing longitudinal studies of aging samples have come out inconsistent findings. Some studies suggest that functional disability contributes to the increase in depression over time (Gayman et al., 2008; Kivela, KongasSaviaro, Kimmo, Kesti, & Laippala, 1996; Schieman & Plickert, 2007; Yang & George, 2005). Some studies conclude that functional disability is not related to changes in depressive symptoms (Chou & Chi, 2000). The cross-sectional association between leisure or social activities and low-level depression has been demonstrated by several studies (Janke, Nimrod, & Kleiber, 2008; Kwag, Martin, Russell, Franke, & Kohut, 2011). Recent longitudinal works further indicated that a reduction in physical or social activities over time is related to increased risk for future depression (Chiao, Weng, & Botticello, 2011; Glass, Mendes De Leon, Bassuk, & Berkman, 2006; Hong, Hasche, & Bowland, 2009; Isaac, Stewart, Artero, Ancelin, & Ritchie, 2009). Moreover, perceived stress can mediate the detrimental effect of negative life events on depression. Specifically, functional disability is positively associated with perceived stress, while perceived stress is directly related to higher levels of depression (Kwag et al.,

2011; Scott, Jackson, & Bergeman, 2011). As for the protective role of social support, a study of elderly Taiwanese subjects with debilitating illnesses performed by Liu (1999) finds that those who receive social support tend to report better emotional well-being than those who do not. Compared to objective measure of social support, one’s subjective appraisal of support received is a more powerful predictor of depressive symptoms in later life (Chao, 2011). Also, high availability of social support can reduce the maladaptive psychological reaction caused by stress and make it less stressful for an individual (Falcon et al., 2004; Kwag et al., 2011). Despite a growing number of studies examining the cross-sectional effects of activity restriction, perceived stress and social support against functional disability on depressive symptoms, little is known about how these factors interact to exert longitudinal influences on older people’s emotional well-being over time. This innovative study is particularly valuable on using SPM to investigate depressive symptoms that accompany functional disability among elderly Chinese. The utilization of three-wave data from a nationally representative sample acquired in Taiwan enables researchers to explore how prior functional disability may affect changes in depressive symptoms at followups through the interrelationships of intervening activity restriction, perceived stress, and social support. Methods Conceptual framework Figure 1 shows the conceptual framework of this study. This model is one of the four ‘pure’ longitudinal models suggested by Menard (2002). This model is superior in that

Figure 1. A conceptual model of functional limitation and changes in CES-D.

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Aging & Mental Health it tests the temporal order among SPM components by applying the following three procedures: (1) to control for the effects of unmeasured variables and to provide a more conservative test of causal relationships, use the prior value of the endogenous variable as a predictor of the future value of the same variable; (2) to test the instantaneous effect, use the prior value of the endogenous variable as a predictor of the prior value of the exogenous variable; and (3) to test the lagged effect, use the prior value of the endogenous variable as a predictor of the more recent value of the exogenous variable (Menard, 2002). While a number of relationships are specified in Figure 1, this research is interested in understanding the following linkages in order to test the SPM assumptions: Hypothetically, (a) high functional disability is related to high levels of depressive symptoms at the same wave and in later waves; and (b) high functional disability is related to high activity restriction, high perceived stress and low social support at the same wave and in later waves, which in turn predict high levels of depressive symptoms at the same wave and in later waves. Sample Data for this study were from the ‘Survey of Health and Living Status of the Elderly’ (SHLSE) in Taiwan. The SHLSE is a longitudinal panel survey that was first conducted in 1989. The initial survey in 1989 is a nationally representative sample, including persons aged 60 or over as of the end of 1988 (n ¼ 4049). The sample was selected based on a three-stage stratified equal probability sampling method. The first stage sample was drawn from 56 townships, followed by blocks, and lastly, two respondents were selected systematically from each selected block. The age distribution of the baseline survey is similar to the population at the data collection point. The participants were re-interviewed periodically in 1993 (n ¼ 3155), 1996 (n ¼ 2669), 1999 (n ¼ 2310), 2003 (n ¼ 1743) and 2007 (n ¼ 1268). Even through the response rates are more than 90% in the follow-ups of the SHLSE, the accumulative attrition is inevitable for a sample of elderly people. By the end of 2007, a total of 2633 participants deceased during the 18-year period, which accounted for 95% of the sample attrition. The first three waves were excluded because responses to items for social activities and perceived stress, the two major factors of interested in this study, were first collected by the 1999 survey. All 1268 participants who completed the 2007 survey were included because this selected sample contains information on the three major time-varying variables (i.e., perceived stress, social support, and depressive symptoms) used in this study across 1999, 2003, and 2007 surveys. The inclusion of this selected sample enables researchers to make a meaningful comparison on changes in these time-varying variables within the same group of participants. For clarity, time 1 (T1) refers to the 1999 survey; time 2 (T2) refers to the 2003 survey; and time 3 (T3) refers to the 2007 survey. Participants in this study were aged 74–106 years (M ¼ 82.72, SD ¼ 4.05) in 1999. In total, 49.3% of

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participants were female. The average years of education were 0–17 years (M ¼ 5.00, SD ¼ 4.76). Compared to those who remained in the study, binary logistic regression results revealed that those who dropped out tended to be older (OR 1.15, 95% CI: 1.14–1.17) and male (OR 0.70, 95% CI: 0.61–0.80). They also had less education (OR 0.96, 95% CI: 0.94–0.97) and received less social support (OR 0.83, 95% CI: 0.77–0.90). Additionally, they reported more depressive symptoms (OR 1.20, 95% CI: 1.10–1.32) and greater functional disability (OR 3.03, 95% CI: 2.53–3.62) at baseline. Due to the nonrandom subject attrition, research findings from this study can only be generalized to older individuals in Taiwan with better physical function, more social support, and fewer depressive symptoms.

Measures Depression Depression was constructed from responses to a 10-item version of the Center for Epidemiological Studies Depression Scale (CES-D) (Radloff, 1977). Respondents were asked how often they had experienced the feeling in the past week, including eight negative items (e.g., ‘poor appetite,’ ‘everything I did was an effort,’ ‘restless sleep,’ ‘depressed,’ ‘lonely,’ ‘people around me are unfriendly,’ ‘sad,’ and ‘could not get myself going’) and two positive items (e.g., ‘happy’ and ‘joyful life’). Responses to each item ranged from 0 to 3 (0 ¼ no, 1 ¼ rarely or only one day, 2 ¼ sometimes or two to three days, 3 ¼ always or four days or more). The two positive items were reverse recoded so that a high score indicated greater depression. Cronbach’s alpha coefficients for this scale were 0.85 in 1999, 0.84 in 2003, and 0.85 in 2007. Functional disability Functional disability was measured by the number of physical limitations in performing five IADL tasks, including grocery shopping, managing finances, taking bus or train alone, doing heavy housework, and doing light housework. Respondents were asked to indicate their difficulty performing the task on a scale from 0 (no difficulty) to 3 (unable to perform the task). A higher summated score on the five items indicated higher levels of functional disability. Activity restriction Activity restriction was measured in three dimensions: reduced participation in leisure activities, volunteering, and formal organizations. Respondents were asked whether they reduced or stopped these activities in the past one year due to health reasons. Those who responded ‘no’ were assigned a value of 0; those that responded ‘yes’ were assigned a value of 1. A higher summed score indicated more activity restrictions. Perceived stress Perceived stress was assessed according to self-reported feelings about how much participants worried about their

Table 1 presents descriptive analysis results and the correlation matrix of key variables in this study. The results from one-way ANOVA showed a significant increase in

– .388 16.13 (3.00) 4–20  .380 .382 16.29 (2.97) 4–20 – .085 .120 .145 0.48 (0.67) 0–2 – .317 .092 .149 .114 0.44 (0.65) 0–2 – .352 .267 .160 .084 .140 0.48 (0.66) 0–2 – .293 .218 .117 .048 .009 .018 0.79 (0.87) 0–3 – .320 .368 .249 .164 .065 .018 .029 1.78 (3.27) 0–15

10 8 7 6 5 4 3

– .178 .148 .314 .330 .556 .189 .255 .356 6.26 (6.04) 0–30 – .472 .266 .214 .317 .513 .313 .225 .363 .256 5.66 (5.82) 0–29 Note: p  0.05, p  0.01,  p  0.001.

Results

– .443 .399 .429 .272 .507 .360 .324 .341 .203 .260 5.49 (5.71) 0–30

Analytic plan For simultaneous analysis of the hypothesized linkages among key factors, a path analysis was performed using AMOS 19.0 (Arbuckle, 2010; Byrne, 2001; Kline, 2011). The full information maximum likelihood (FIML) procedure was used to address missing data (Arbuckle, 2010; Ender, 2001). When modeling incomplete data, the estimates produced by FIML are comparable to those obtained by more complex procedures such as multiple imputation (Krause, 2011; Newman, 2003).

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Control variables Four participant characteristics that can potentially affect the level of functional disability and depression were controlled in this study, including age, gender, education (in years of formal education), and cognitive status (Liu, Chi, Chen, Song, & Zheng, 2009; Tung & Mutran, 2005; Vinkers, Gussekloo, Stek, Westendorp, & Mast, 2004; Zhang, Li, & Feldman, 2005). The cognitive status was measured with the 10-item Short Portable Mental Status Questionnaire (SPMSQ) (Pfeiffer, 1975). The study participants were asked to identify their address, location, the date when interviewed, the day of the week when interviewed, their age, their mother’s maiden name, the names of the current president and the president before him, their date of birth, and to count backward from 20 by threes. A correct response was given a value of 0, while incorrect was given a value of 1. The summated scores for these 10 items were calculated. The higher scores indicated greater cognitive deficits. The average SPMSQ scores for the study participants were 1.44 (SD ¼ 2.225) in 1999; 1.92 (SD ¼ 2.601) in 2003; and 3.35 (SD ¼ 3.424) in 2007.

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Social support was assessed by four related items. Respondents were asked the following questions: ‘How willing is your family and friends to listen to you when you talk about something?’ ‘How satisfied are you with the emotional support from family or friends?’ ‘How much do you feel your family and friends care about you?’ and ‘How much you can rely on family or friends when you are sick and need assistance?’ Responses were coded as 1 (not at all or very unwilling/dissatisfied) to 5 (very much/willing /satisfied). A high score reflects a high level of social support.

Table 1. Sample characteristics and zero-order correlations among key model variables.

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Social support

CES-D (T1) CES-D (T2) CES-D (T3) Functional disability (T1) Activity restriction (T1) Perceived stress (T1) Perceived stress (T2) Perceived stress (T3) Social support (T1) Social support (T2) Social support (T3) Mean (SD) Range

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health status. Responses were on scale of 0–2 (0 ¼ not feeling stressed; 1 ¼ feeling a little stressed; and 2 ¼ feeling very stressed). As the score increased, perceived stress increased.

– 16.15 (2.75) 4–20

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Figure 2. Standardized regression coefficients of path analysis (only significant paths shown). Note: N ¼ 1268, x2 ¼ 156.22, df ¼ 29, RMSEA ¼ 0.059, CFI ¼ 0.974. Control variables: age, education, sex, cognitive status.

Since no two variables in Table 1 exhibited a correlation greater than 0.85, multicollinearity does not pose a problem in this study (Crown, 1998). Figure 2 depicts standardized regression coefficients of path analysis that are statistically significant. The hypothesized model yielded a satisfactory fit with the data (Comparative Fit Index [CFI] ¼ 0.974, Root Mean Square Error of Approximation [RMSEA] ¼ 0.059). The cross-sectional and longitudinal effects of functional disability, activity restriction, perceived stress and social support to depressive symptoms are shown in Table 2.

the CES-D scores from T1 to T3, indicating that depressive symptoms grew with the passage of time. The cross-time differences for perceived stress and social support were not statistically significant, suggesting that perceived stress and social support were relatively stable across waves. For the correlation matrix, Finkel (1995) noted that the inclusion of the same measures for multiple waves into the same model is appropriate when examining lag relationships. However, one should be aware of possible multicollinearity when measures are extremely stable (p. 14).

Table 2. Impact of functional disability on depression: standardized direct and indirect effects. Outcome CES-D (T1)

T1 Functional disability Activity restriction Perceived stress Social support CES-D T2 Perceived stress Social support CES-D T3 Perceived stress Social support

CES-D (T2)

CES-D (T3)

Direct

Indirect

Total

Direct

Indirect

Total

Direct

Indirect

Total

.220 .076 .412 .223 –

.158 .053 – .078 –

.378 .129 .412 .301 –

.028 .062 .001 .017 .197

.194 .066 .222 .179 –

.222 .128 .223 .196 .197

.001 .016 .011 .022 .122

.159 .072 .229 .199 .048

.160 .088 .218 .177 .170

– – –

– – –

– – –

.404 .231 –

– .078 –

.404 .309 –

.038 .009 .242

.243 .191 –

.205 .200 .242

– –

– –

– –

– –

– –

– –

.440 .199

– .038

.440 .237

Note: p  0.05, p  0.01,  p  0.001 (two-tailed test).

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Cross-sectional effects of functional disability, activity restriction, perceived stress, social support on depressive symptoms Direct effects In Figure 2, T1 functional disability, activity restriction, perceived stress, social support were all directly associated with T1 depressive symptoms. When adjusting for T1 activity restriction, perceived stress, social support and control variables, one standard deviation increase in the level of T1 functional disability predicted 0.220 standard deviations increase in T1 depressive symptoms. When control for T1 functional disability, perceived stress, social support and control variables, one standard deviation increase in the degree of activity restriction was associated with 0.076 standard deviations increase in the level depressive symptoms in the same wave. Likewise, one standard deviation increase in the level of perceived stress at T1 was related to 0.412 standard deviations increase in T1 depressive symptoms, adjusting for other factors and control variables. In contrast, one standard deviation increase in T1 social support predicted 0.223 standard deviations decrease in T1 depressive symptoms, after controlling for other factors and control variables. The standardized path coefficients also enable comparisons of the relative importance of studied factors. Among the four factors, perceived stress yielded the strongest direct effect on depressive symptoms, followed by social support, functional disability and, lastly, activity restriction. Indirect effects Table 2 shows the analytical results, which indicate that T1 functional disability had a significant indirect effect on T1 depressive symptoms. The level of T1 depressive symptoms is expected to increase by 0.158 standard deviations for every increase in one standard deviation of T1 functional disability via its effect on T1 activity restriction, perceived stress, and social support. As can be seen from Figure 2, T1 functional disability has three possible indirect paths to increasing T1 depressive symptoms: increased activity restriction (T1 disability to T1 activity restriction), increased perceived stress (T1 disability to T1 perceived stress), and decreased social support (T1 disability to T1 social support). Total effects In Table 2, considering all presumed direct and indirect links, one standard deviation increase in T1 functional disability, activity restriction, and perceived stress are expected to increase T1 depressive symptoms by 0.378, 0.129, and 0.412 standard deviations, respectively. In contrast, one standard deviation increase in T1 social support is associated with 0.301 standard deviations decrease in T1 depressive symptoms. Notably, of the three intervening variables, perceived stress still yielded the strongest standardized total effect on depressive symptoms, followed by social support and, lastly, activity restriction.

Longitudinal effects of functional disability on depressive symptoms: the roles of activity restriction, perceived stress, and social support Effects of prior functional disability on depressive symptoms at follow-ups In Table 2, functional disability at T1 yielded significant total and indirect effects on depressive symptoms at T2 (total effect: .222, p  0.01; indirect effect: .194, p  0.01) and T3 (total effect: .160, p  0.01; indirect effect: .159, p  0.001), respectively. However, the direct effects of T1 functional disability on T2 (b ¼ .028, n.s.) and T3 (b ¼ .001, n.s.) depressive symptoms were not statistically significant. That is, the significant total effects of T1 functional disability on subsequent depressive symptoms were mostly indirect effects exerted through intervening activity restriction, perceived stress and social support. For example, T1 functional disability can indirectly affect T3 depressive symptoms through at least three possible paths: through activity restriction in T1 to changes in depressive symptoms between T1 and T3, through changes in perceived stress between T1 and T3 to depressive symptoms at T3, and through changes in social support between T1 and T3 to depressive symptoms at T3. Effects of prior activity restriction, perceived stress, and social support on depressive symptoms at follow-ups Table 2 shows that high activity restriction and perceived stress at T1 predicted high depressive symptom levels at T2 (activity restriction: total effect ¼ .128, p  0.01; perceived stress: total effect ¼ .223, p  0.01) and T3 (activity restriction: total effect ¼ .088, p  0.001; perceived stress: total effect ¼ .218, p  0.01). In contrast, high social support at T1 predicted low depressive symptom levels at T2 (total effect ¼ 0.196, p  0.01) and T3 (total effect ¼ 0.177, p  0.01). The findings revealed that T1 activity restriction and perceived stress were positively associated with depressive symptom scores over time, while social support at T1 was negatively associated with depressive symptom scores over time. That is, the detrimental effects of prior activity restriction and perceived stress on depressive symptoms remained significant at follow-up. Additionally, the beneficial effect of prior social support on depressive symptoms persisted throughout the 8-year period of this study. Notably, the last column of Table 2 shows that, T1 perceived stress exerted a stronger longitudinal effect on T2 (total effect ¼ .222, p  0.01) and T3 depressive symptoms (total effect ¼ .218, p  0.01) than did T1 functional disability, activity restriction, and social support. Disabled older individuals who worried less about their health not only had fewer depressive symptoms at the same wave, but also reported significantly fewer depressive symptoms at follow-ups. Compared to other factors studied, perceived stress can be regarded as the strongest predictor of current and future symptoms of depression.

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Table 3. Longitudinal standardized effects of functional disability, activity restriction, perceived stress, and social support. Outcome Perceived stress (T2) Direct

Indirect

Total

Social support (T2) Direct Indirect

Total

Perceived stress (T3) Direct

Indirect

Total

Social support (T3) Direct Indirect

Total

T1 .143 .141 .006 .024 .030 Functional disability .116 .121 .237 .002 .023 .025 .002 – – – .011 .058 .069 – – – Activity restriction .055 .045 .100 Perceived stress .348 – .348 – – – .200 .115 .315 – – – Social support .055 .138 .083 .373 – .373 .027 .121 .094 .274 .106 .380 T2 – .329 – – – Perceived stress – – – – – – .329 Social support .194 – .194 .064 .088 .152 .283 – .283

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Note: p  0.05, p  0.01, p  0.001 (two-tailed test).

Longitudinal interrelationships among functional disability, activity restriction, perceived stress, and social support Table 3 shows the longitudinal relationships among functional disability, activity restriction, perceived stress, and social support. High functional disability at T1 was associated with high perceived stress at T2 (total effect ¼ .237, p  0.01) and T3 (total effect ¼ .141, p  0.001). Similarly, the number of activity restrictions at T1 was positively correlated with the perceived stress at T2 (total effect ¼ .100, p  0.001) and T3 (total effect ¼ .069, p  0.05). High social support at T1 was also associated with low perceived stress at T2 (total effect ¼ 0.083, p  0.01) and T3 (total effect ¼ 0.094, p  0.01). Lastly, T1 functional disability yielded mild indirect effects on social support at T2 (indirect effect ¼ .023, p  0.05) and T3 (indirect effect ¼ .024, p  0.05), respectively. In summary, this longitudinal study provides empirical evidence of the temporal order among the factors studied. Figure 2 and Tables 2 and 3 show that, compared to participants with low functional disability, those with high functional disability at T1 were less likely to participate in social and leisure activities in the same wave (b ¼ .269, p  0.001). High activity restriction at T1 was associated with high perceived stress at T2 (total effect ¼ .100, p  0.001), while high perceived stress at T2 predicted high depressive symptom levels at T3 (total effect ¼ .205, p  0.01). Also, the presence of functional disability at T1 was indirectly related to low social support at T2 (indirect effect ¼ .023, p  0.05), while social support at T2 was negatively related to more depressive symptoms at T3 (total effect ¼ .200, p  0.01). Last, the hypothesized model accounts for 45.7% of the total effect of T1 depressive symptoms, 42.7% of T2 depressive symptoms, and 43.0% of T3 depressive symptoms. Discussion This innovative study makes several major contributions to the literature. First, to the best of our knowledge, this is the first documented use of SPM to investigate how functional disability affects changes in depressive symptoms in an elderly Chinese population. Second, applying path

analysis enables simultaneous capture of the interrelations among key components that may affect the severity of depressive symptoms in disabled elderly adults. Last, this study analyzes longitudinal data collected from a nationwide sample of elderly adults in Taiwan over an eightyear period. With multiple data collection points, a more convincing sequence of time priority can be established (Fortune & Reid, 1999). First, the hypothesized effect of functional disability on current and future depressive symptoms was evident. In accordance with the literature, symptoms of depression were directly affected by functional disability in the same wave (Gayman et al., 2008; Yang, 2006; Yang & George, 2005). The analytical results further indicated that functional disability had a significant positive total effect on subsequent depressive symptom levels. That is, in addition to the positive cross-sectional association between functional disability and depressive symptoms, individuals with functional disability at T1 also had more numerous depression symptoms at the 4-year and 8-year followups compared to those without, which suggests that the presence of functional disability is a significant risk factor for future depressive symptoms. In response to the second hypothesis, this study showed that older individuals who stop participating in social and leisure activities for health reasons tend to exhibit more depression symptoms compared to their more active peers. Continuing social and leisure activity participation can reduce depression risk in older adults by providing social contact and by stimulating physical and cognitive functioning (Glass et al., 2006). This research extends previous work by demonstrating the longitudinal relationship between activity restriction and depressive symptoms. The significant association between activity restriction and depressive symptoms at follow-ups suggests that the detrimental effect of activity restriction on depressive symptoms is not only cross-sectional, but also occurs over time. Even though the benefit of activity participation on depressive symptoms is supported, high functional disability was found to be related to high activity restriction. As noted by Johnson and Barer (1992), older individuals with physical limitations tend to have less social engagement than those without physical limitations. In brief,

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physical disability may restrict older people’s ability to attend formal or informal activities and make them lose attachments to social roles, thus leading to an increase risk of developing depressive symptoms (George, 2011). Notably, perceived stress was a more powerful predictor of current and future symptoms of depression than functional disability, activity restriction and social support. Herein, the mediating role of perceived stress was confirmed because it showed a greater direct impact on the symptoms of depression over negative life event itself (Kline, 2011). As suggested by Norris and Murrell (1990), perceived stress is considered a subjective manifestation of functional disability because it reflects the increased pressure, inconvenience, and strain resulting from the stressful event. All these experiences may trigger negative effect and produce psychological distress. In other words, the severity of functional disability is not the main determinant of depressive symptoms in older people. Other contributors include how they sense and interpret their situation after the occurrence of disability, which is what actually determines the mental health consequences. Moreover, perceived stress can also be viewed as a function of coping resources when dealing with stress (Cohen, Kamarck, & Mermelstein, 1983). Internal resources such as self-esteem and external resources such as social support can protect an individual with functional disability against psychological distress by altering stressor appraisal process or stimulating positive appraisal. The perception of stress is an emotional manifestation to insufficient resources for coping with the stressful situation, and is therefore considered an outcome of the coping process (Cohen, Kamarck, & Mermelstein, 1983). In this study, the appraised stress appears to be more closely related to depressive symptoms than external coping resources (i.e., social support and activity participation) and exerts as a stronger determinant of current and future depressive symptoms over these resources. In terms of the effect of social support, after adjusting for functional disability, activity restriction, perceived stress and control variables, social support was negatively related to severity of depression symptoms, both crosssectionally and over time. The analysis results confirm the protective effect of social support against the manifestation of depressive symptoms in old age (Chao, 2011, 2012). However, the analytic results further revealed that disabled elders were less likely to receive social support from families and friends compared to nondisabled elders. The findings also held true over time. Previous studies have suggested that researchers should consider the nature of stressors and the type of support when studying the relationships among stressors, social support and mental health outcomes. Acute illness such as recent deaths may increase social contact or emotional support within a short time. Chronic illness that requires long-term and continued assistance may limit older individuals’ ability to reciprocate in exchanges within their informal networks, weaken their social bonds, and reduce quantity or quality of emotional social support received (Hyduk, 1997; Krause & Jay, 1991; Taylor & Lynch, 2004; Yang, 2006). In this instance, functional disability limits older

individuals’ ability to engage in social relationship and maintain social ties, lowers satisfaction with social support received, and lowers the expectation that significant others will provide assistance when needed. Therefore, depressive symptoms tend to increase. Additionally, subjects who had high satisfaction with social support or high anticipated support from families and friends were less likely to perceive their health status as stressful. This relationship was consistent with earlier studies among elderly people in the United States (Falcon et al., 2004; Kwag et al., 2011). However, the causes are poorly understood in older adults. Previous works of younger generations suggested that receiving satisfactory support or having a high level anticipated support results in the belief that care will be provided when the need arises. This belief can diminish stress caused by a declining health status (Khodarahimi, Hashim, & MohdZaharim, 2012). Another plausible explanation is that an external resource like sufficient support can strengthen internal resources (e.g., self-esteem or mastery), which increases the capability to manage stress (Bovier, Chamot, & Perneger, 2004). Lastly, the analytical model shows that T1 functional disability and activity restriction were positively associated with T2 perceived stress and negatively associated with T2 social support, whereas T2 perceived stress and social support were negatively associated with depressive symptoms at T3. According to the SPM assumptions, prior functional disability contributes to subsequent symptoms of depression for two reasons. First, it directly inhibits participation in leisure and social activities. Both prior functional disability and activity restriction can elevate subsequent perceived stress, which increases depressive symptoms during the 8-year follow-up in this study. Second, prior functional disability lowers social support satisfaction and anticipated support, whereas inadequate social support contributes to the manifestation of depressive symptoms afterwards. The findings have important implications for practitioners and policymakers serving Taiwanese older persons with functional disability. Any program designed to promote activity participation, enhance social support satisfaction, facilitate anticipated support, and reduce perceived stress would benefit the emotional well-being of disabled elders. The benefits of different programs could come together to exhibit a better mental health outcome. Services are never too late to implement since even those provided after the onset of disability can improve mental health. The current investigation also emphasizes the importance of screening for possible intervening mechanisms (e.g., affective temperament profile and hopelessness), which may influence older individuals’ psychosocial functioning and affect the association between functional disability and future depressive symptomology (Pompili et al., 2013). This study has several noted limitations. First, perceived stress was measured by one single indicator asking older individuals’ feelings regarding their health status in the longitudinal data. Therefore, only path analysis was applied for the analysis. Multiple indicators of perceived

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Aging & Mental Health stress are suggested for future research. Second, whereas the longitudinal analysis used in this study is superior for testing the proposed temporal ordering among functional disability, activity restriction, perceived stress, social support, and depressive symptoms, the causal relationships between two key factors from the same wave should be interpreted cautiously. For instance, Figure 2 suggests that T1 functional disability is the ‘cause’ of T1 depressive symptoms. Arguably, T1 depressive symptoms lead to an increase in T1 functional disability. Similarly, the study model assumes that T1 social support reduces T1 perceived stress. However, emerging stress could be the cause of low perceived social support. Third, this study used self-reported functional disability rather than an objective assessment of physical functioning. Although previous research has found that this may not cause major concern to the validity of findings (Gayman et al., 2008; Yang, 2006), the analytical results may differ from those obtained when an objective assessment of physical status is used. Fourth, since perceived stress, social support, and depressive symptoms are all subjective impressions from the same individual, these subjective measures may not be completely independent. Lastly, due to the limited data obtained in this survey, the analysis could not include other factors that may affect the relationship between functional disability and depressive symptoms such as coping strategies, spirituality, religiosity, neighborhood, or environmental characteristics. Further study is needed to examine the effects of these factors. Acknowledgements The data in this study was provided by Bureau of Health Promotion, Department of Health, Taiwan, Republic of China.

References Alexopoulos, G.S. (2005). Depression in the elderly. The Lancet, 365, 1961–1970. Arbuckle, J.L. (2010). IBM SPSS Amos 19 user’s guide. Chicago, IL: SPSS. Boey, K.W. (2001). Contribution of chronic life strain to mental health status of Chinese older adults. Journal of Gerontological Social Work, 35, 39–52. Bovier, P.A., Chamot, E., & Perneger, T.V. (2004). Perceived stress, internal resources, and social support as determinants of mental health among younger adults. Quality of Life Research, 13, 161–170. Byrne, B.M. (2001). Structural equation modeling with AMOS: Basic concepts, applications, and programming. Mahwah, NJ: Lawrence Erlbaum Associates. Chao, S.F. (2011). Assessing social support and depressive symptoms in older Chinese adults: A longitudinal perspective. Aging & Mental Health, 15, 765–774. Chao, S.F. (2012). Functional disability and psychological wellbeing in later life: Does source of support matter? Aging & Mental Health, 16, 236–244. Chiao, C., Weng, L.J., & Botticello, A.L. (2011). Social participation reduces depressive symptoms among older adults: An 18-year longitudinal analysis in Taiwan. BMC Public Health, 11, 292–100. Chou, K.L., & Chi, I. (2000). Stressful events and depressive symptoms among old women and men: A longitudinal study.

775

International Journal of Aging and Human Development, 51, 275–293. Chou, K.L., & Chi, I. (2005). Prevalence and correlates of depression in Chinese oldest-old. International Journal of Geriatric Psychiatry, 20, 41–50. Cohen, S., Kamarck, T., & Mermelstein, R. (1983). A global measure of perceived stress. Journal of Health and Social Behavior, 24, 385–396. Crown, W.H. (1998). Statistical models for the social and behavioral sciences: Multiple regression and limited-dependent variable models. Westport, CT: Praeger Publishers. Enders, C.K. (2001). A primer on maximum likelihood algorithms available for use with missing data. Structural Equation Modeling, 8, 128–141. Falcon, L. M., Todorova, I., & Tucker, K. (2009). Social support, life events, and psychological distress among the Puerto Rican population in the Boston area of the United States. Aging & Mental Health, 13, 863–873. Finkel, S. E. (1995). Causal analysis with panel data. Thousand Oaks, CA: Sage. Fortune, A.E., & Reid, W.J. (1999). Research in social work (3rd ed.). New York: Columbia University Press. Gayman, M.D., Turner, R.J., & Cui, M. (2008). Physical limitations and depressive symptoms: Exploring the nature of the association. Journals of Gerontology Series B: Psychological Sciences & Social Sciences, 63B, S219–S228. Gignac, M.A.M., Cott, C., & Badley, E.M. (2000). Adaption to chronic illness and disability and its relationship to perceptions of independence. Journals of Gerontology Series B: Psychological Sciences & Social Sciences, 55B, 362– 372. Glass, T.A., Mendes De Leon, C.F., Bassuk, S.S., & Berkman, L.F. (2006). Social engagement and depressive symptoms in late life. Journal of Aging & Health, 18, 604–628. George, L.K. (2011). Social factors, depression and aging. In R.H. Binstock & L.K. George (Eds.), Handbook of aging and the social sciences (pp. 149–162). Boston, MA: Elsevier Academic Press. Hong, S.L., Hasche, L., & Bowland, S. (2009). Structural relationships between social activities and longitudinal trajectories of depression among older adults. Gerontologist, 49, 1– 11. Hsu, H.C. (2007). Exploring elderly people’s perspectives on successful aging in Taiwan. Aging & Society, 27, 81–102. Hsu, H.C., & Tung, H.J. (2010). What makes you good and happy? Effects of internal and external resources to adaptation and psychological well-being for the disabled elderly in Taiwan. Aging & Mental Health, 14, 851–860. Hyduk, C.A. (1997). The dynamic relationship between social support and health in older adults: Assessment implications. Journal of Gerontological Social Work, 27, 1149–1165. Isaac, V., Stewart, R., Artero, S., Ancelin, M.L., & Ritchie, K. (2009). Social activity and improvement in depressive symptoms in older people: A prospective community cohort study. American Journal of Geriatric Psychiatry, 17, 688–696. Janke, M., Nimrod, G., & Kleiber, D. (2008). Leisure activity and depressive symptoms of widowed and married women in later life. Journal of Leisure Research, 40, 250–266. Johnson, C.L., & Barer, B.M. (1992). Patterns of engagement and disengagement among the oldest old. Journal of Aging Studies, 6, 351–364. Judd, L.L., Schettler, P.J., Solomon, D.A., Maser, J.D., Coryell, W., Endicott, J., . . . Akiskal, H.S. (2008). Psychosocial disability and work role function compared across the longterm course of bipolar I, bipolar II and unipolar major depressive disorders. Journal of Affective Disorders, 108, 49–58. Khodarahimi, S.K., Hashim, I.H.M., & Mohd-Zaharim, N. (2012). Perceived stress, positive-negative emotions, personal values and perceived social support in Malaysian

Downloaded by [University of Ulster Library] at 10:07 17 November 2014

776

S.-F. Chao

undergraduate students. International Journal of Psychology and Behavioral Sciences, 20, 1–8. Kivela, S.L., Kongas-Saviaro, P., Kimmo, P., Kesti, E., & Laippala, P. (1996). Health, health behavior and functional ability predicting depression in old age: A longitudinal study. International Journal of Geriatric Psychiatry, 11, 871–877. Kline, R.B. (2011). Principles and practice of structural equation modeling (3rd ed.). New York: Guilford Press. Krause, N. (2011). Valuing the life experience of older adults and change in depressive symptoms: Exploring an overlooked benefit of involvement in religion. Journal of Aging and Health, 24, 227–249. Krause, N, & Jay, G. (1991). Stress, social. Support, and negative interaction in later life. Research on Aging, 13, 333–363. Kwag, K.H., Martin, P., Russell, D., Franke, W., & Kohut, M. (2011). The impact of perceived stress, social support, and home-based physical activity on mental health among older adults. International Journal of Aging & Human Development, 72, 137–154. Liu, S.J. (1999). The exploration of life attitudes and life satisfaction for elderly with chronic illness (In Chinese). Nursing Research, 7, 294–306. Liu, J., Chi, I., Chen, G., Song, X., & Zheng, X. (2009). Prevalence and correlates of functional disability in Chinese older adults. Geriatrics & Gerontology International, 9, 253–261. Menard, S. (2002). Longitudinal research (2nd ed.). Newbury Park, CA: SAGE. Nemeroff, R., Midlarsky, E., & Meyer, J.F. (2010). Relationships among social support, perceived control, and psychological distress in late life. International Journal of Aging & Human Development, 71, 69–82. Newman, D.A. (2003). Longitudinal modeling with randomly and systematically missing data. Organizational Research Methods, 6, 328–362. Norris, F., & Murrell, S. (1990). Social support, life events, and stress as modifiers of adjustment to bereavement by older adults. Psychology and Aging, 5, 429–436. Paul, C., Ayis, S., & Ebrahim, S. (2006). Psychological distress, loneliness and disability in old age. Psychology, Health and Medicine, 11, 221–232. Pearlin, L.I. (1989). The sociological study of stress. Journal of Health and Social Behavior, 30, 241–256. Pearlin, L.I. (1992). Structure and meaning in medical sociology. Journal of Health and Social Behavior, 33, 1–9. Pearlin, L.I. (2010). The life course and the stress process: Some conceptual comparisons. Journal of Gerontology: Social Sciences, 65B, 207–215. Pearlin, L.I., & Skaff, M.M. (1995). Stressors and adaption in later life. In M. Gatz (Ed.), Emerging issues in mental health (pp. 97–123). Washington, DC: American Psychological Association.

Pfeiffer, E. (1975). A Short Portable Mental Status Questionnaire for the assessment of organic brain deficit in elderly patients. Journal of the American Geriatrics Society, 23, 433–441. Pompili, M., Innamorati, M., Gonda, X., Serafini, G., Sarno, S., Erbuto, D., . . . Girardi, P. (2013). Affective temperaments and hopelessness as predictors of health and social functioning in mood disorder patients: A prospective follow-up study. Journal of Affective Disorders, 150, 216– 222. Radloff, L.S. (1977). The CES-D scale: A self-report depression scale for research in the general population. Applied Psychological Measurement, 1, 385–401. Rose, B.M., Holmbeck, G.N., Coakley, R.M., & Franks, E.A. (2004). Mediator and moderator effects in developmental and behavioral pediatric research. Journal of Developmental and Behavioral Pediatrics, 25, 58–67. Schieman, S., & Plickert, G. (2007). Functional limitations and changes in levels of depression among older adults: A multiple-hierarchy stratification perspective. Journals of Gerontology Series B: Psychological Sciences & Social Sciences, 62B, S36–S42. Scott, S.B., Jackson, B.R., & Bergeman, C.S. (2011). What contributes to perceived stress in later life? A recursive partitioning approach. Psychology & Aging, 26, 830–843. Taylor, M.G., & Lynch, S.M. (2004). Trajectories of impairment, social support, and depressive symptoms in later life. Journals of Gerontology Series B: Psychological Sciences & Social Sciences, 59B, S238–S246. Tsai, Y.F., Yeh, S.H., & Tsao, H.H. (2005). Prevalence and risk factors for depressive symptoms among community-dwelling elders in Taiwan. International Journal of Geriatric Psychiatry, 20, 1097–1102. Tung, H.J., & Mutran, E.J. (2005). Ethnicity and health disparities among the elderly in Taiwan. Research on Aging, 27, 327–254. Vinkers, D.J., Gussekloo, J., Stek, M.L., Westendorp, R.G.T., & Mast, R.S. (2004). Temporal relation between depression and cognitive impairment in old age: Prospective population based study. British Medical Journal, 329, 881–883. Yang, Y. (2006). How does functional disability affect depressive symptoms in late life? The role of perceived social support and psychological resources. Journal of Health and Social Behavior, 47, 355–372. Yang, Y., & George, L.K. (2005). Functional disability, disability transitions, and depressive symptoms in late life. Journal of Aging & Health, 17, 263–292. Zhang, W., Li, S., & Feldman, M.W. (2005). Gender differences in activity of daily living of the elderly in rural China: Evidence from Chaohu. Journal of Women & Aging, 17(3), 73–89.