C International Psychogeriatric Association 2014 International Psychogeriatrics (2014), 26:9, 1465–1473 doi:10.1017/S1041610214000994
Self-efficacy moderation and mediation roles on BPSD and social support influences on subjective caregiver burden in Chinese spouse caregivers of dementia patients ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Shuying Zhang,1 Qihao Guo,2 Helen Edwards,3 Patsy Yates3 and Chunbo Li4 1
Tongji University School of Medicine, Shanghai, China Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China 3 Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia 4 Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Institute of Mental Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2
ABSTRACT
Background: This study aims to explore moderation and mediation roles of caregiver self-efficacy between subjective caregiver burden and (a) behavioral and psychological symptoms (BPSD) of dementia; and (b) social support. Methods: A cross-sectional study with 137 spouse caregivers of dementia patients was conducted in Shanghai. We collected demographic information for the caregiver–patient dyads, as well as information associated with dementia-related impairments, caregiver social support, caregiver self-efficacy, and SF-36. Results: Multiple regression analysis showed that caregiver self-efficacy was a moderator both between BPSD and subjective caregiver burden, and social support and subjective caregiver burden. Results also showed a partial mediation effect of caregiver self-efficacy on the impact of BPSD on subjective caregiver burden, and a mediation effect of social support on subjective caregiver burden. Caregiver self-efficacy and subjective burden significantly influenced BPSD and social support. Conclusion: Caregiver self-efficacy played an important role in the paths by which the two factors influenced subjective burden. Enhancing caregiver self-efficacy for symptom management (particularly BPSD) can be an essential strategy for determining interventions to support dementia caregivers in China, and possibly in other countries. Key words: caregiver self-efficacy, BPSD, dementia, family caregiver, social support, subjective caregiver burden
Introduction Self-efficacy is a cognitive construct that refers to an individual’s belief in his or her capacity to successfully accomplish a specific task in confronting different barriers (Bandura, 1997). Self-efficacy has received increasing attention in the literature of family caregiving for people with dementia (Pinquart and Sörensen, 2003a; 2007; Au et al., 2009; Rabinowitz et al., 2009). Many studies showed that compared to other dementia-related impairments including cognitive and physical impairment, the behavioral and psychological symptoms of dementia (BPSD; Finkel et al., 1997) were the primary barriers Correspondence should be addressed to: Chunbo Li, Shanghai Mental Health Center, 600 Wan Ping Nan Rd, Shanghai 200030, China. Phone: 86-213477 3243; Fax: 86-21-6438 7986. Email: [email protected] Received 22 Oct 2013; revision requested 10 Mar 2014; revised version received 7 Apr 2014; accepted 1 May 2014. First published online 16 June 2014.
impairing dementia caregivers’ (CGs) confidence in managing care (Zeiss et al., 1999; Pinquart and Sörensen, 2003a; Depp et al., 2005); while social support was the resource enhancing CGs’ sense of self-efficacy (Zeiss et al., 1999; Steffen et al., 2002; Gottlieb and Rooney, 2003; Depp et al., 2005; Au et al., 2009). Other data show that a stronger sense of caregiver self-efficacy positively influenced CGs’ own health-related outcomes, such as reduced subjective burden (Pinquart and Sörensen, 2003a; 2003b; 2007), fewer negative emotions (Au et al., 2009; Rabinowitz et al., 2009), and better physical health (Pinquart and Sörensen, 2003a; 2007). Compared to the extensive studies on the direct influence that caregiver self-efficacy exerts on variables (such as BPSD and social support) related to caregiving situations and CGs’ health outcomes, research exploring indirect effects of self-efficacy has remained limited, particularly the
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Figure 1. Hypothesized moderation effects of caregiver self-efficacy on the relationships between the behavioral and psychological symptoms of dementia (BPSD)/social support and caregiver subjective burden.
ways in which CG self-efficacy might influence associations of BPSD and social support with CGs’ health-related outcomes (e.g., depression, anxiety, subjective burden, and quality of life). According to Bandura (1997), self-efficacy influences both the strategies individuals envision for reaching their goals and the efficiency and effectiveness of their problem-solving. When confronting the same situation (e.g., responding to the same severity of BPSD or perceiving the same level of social support), individuals with strong self-efficacy may regard the condition as a challenge, deal with problems using more effective strategies, and exert themselves to overcome challenges. On the other hand, individuals with a weak sense of self-efficacy doubt their capability to master the task, tend to give up easily, and experience failure more readily. Consequently, those with low self-efficacy for managing stressors may develop negative emotions, such as anxiety and depression. As an example, Rabinowitz et al., (2009) found a moderating role for caregiver self-efficacy between the relationship of BPSD and CGs’ depressive symptoms. Social support has been regarded as another situational factor influencing caregiver self-efficacy and health-related outcomes. Relatively few studies have explored the moderation effect of caregiver self-efficacy on the relationship between social support and CGs’ health-related outcomes. In addition to the research exploring that moderation effect, Au et al., (2009) reported that caregiver self-efficacy was the partial mediator of the relationship between social support and CGs’ depressive symptoms. Our previous study (Zhang et al., 2014) also found a partial mediating effect of caregiver self-efficacy on the influence of social support on CGs’ HRQoL. However, mediation effects of caregiver self-efficacy on the impact of BPSD on CGs’ health-related outcomes have not received much research attention. The studies on moderation or mediation effects have mainly
focused on the links of BPSD and social support with CGs’ depressive symptoms (Au et al., 2009; Rabinowitz et al., 2009) or mental health (Zhang et al., 2013a). In the dementia literature, subjective burden, which refers to the subjective impacts of caregiving on CGs (Pearlin et al., 1990), was an important outcome variable significantly correlated with CGs’ negative emotions, including depression and anxiety (Pinquart and Sörensen, 2003a; 2003b; Cuijpers, 2005; Cooper et al., 2007). Again, however, existing research literature on these relationships is sparse. The moderation and mediation effects of caregiver self-efficacy on this negative emotional outcome need further exploration. Moreover, given differences in cultural attitudes toward care for the elderly, it seems reasonable that the relationships among CG selfefficacy, BPSD, social support, and subjective burden may have a special culturally conditioned character in Chinese culture. Therefore, the current study examined (a) the moderating role of caregiver self-efficacy between BPSD and subjective caregiver burden (Figure 1); (b) the moderating role of caregiver self-efficacy between social support and subjective caregiver burden (Figure 1); and (c) the mediation effects of caregiver self-efficacy on the influences of BPSD and social support on subjective caregiver burden (Figure 2).
Methods Participants We screened an initial sample of 196 caregivers (Zhang et al., 2013b), recruited from the neurological outpatient department of Shanghai Huashan Hospital, to arrive at a sample of 137 spouse CGs (79 wives) who provided the data in the present study. The criterion for inclusion was that the spouse provided most of the care for the patient
Self-efficacy moderation and mediation roles
Figure 2. Hypothesized mediating effects of caregiver self-efficacy on the relationships between the behavioral and psychological symptoms of dementia (BPSD), social support, and caregiver subjective burden.
with dementia (PWD, diagnosed using DSM-IV criteria). Spouses who were simultaneously caring for other relatives with a chronic medical condition were excluded. Permission to use the standard instruments was obtained from the original authors and ethical approval to conduct the study was also obtained by the designated institution prior to the survey. The procedure for recruitment and data collection was described in a previous article (Zhang et al., 2013a). Spouses simultaneously caring for any other relatives with a chronic medical condition were excluded. Thus, 137 spouses CGs completed the survey. Among the 137 participants, 131 participants completed the questionnaires at the hospital, and six at home; the latter were conducted up to 10 days after the hospital visit. The major reason for completing the questionnaires at home was the fatigue associated with doing these on the same day or inconvenience of the transportation to the hospital if participants were selected another day. The mean age of PWDs was 71.0 years old (SD = 8.28), and that of spouse CGs was 69.9 (SD = 8.97) years old. PWDs’ stage of dementia was obtained from their medical records. Among the PWDs, 72 (52.6%) were diagnosed with mild stage of dementia, 25 (18.2%) were at a moderate stage, and 40 (29.2%) were at a severe stage. Measures DEMENTIA-RELATED IMPAIRMENTS AND SUBJECTIVE CAREGIVER BURDEN
The Mini-Mental Status Examination (MMSE) scores were obtained from the PWDs’ medical records. Levels of physical impairment and BPSD were assessed with the Chinese version of the Disability Assessment in Dementia (DAD; Mok et al., 2005) and the Revised Memory and Behavior Problems Checklist (RMBPC; Fuh et al., 1999a), respectively. RMBPC data were reported by the spouses. The DAD assesses instrumental activities of daily living (DAD–IADLs, 25 items) and activities of daily living (DAD–ADLs, 22 items) during the most recent 2 weeks. The total scores on the DAD and on each of the two
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subscales were rated as a percentage of total possible score, with higher scores indicating better physical functioning. The psychometric properties of DAD were satisfactory: the Cronbach’s α for the total score was 0.91, the test–retest reliability was 0.99, and the interrater reliability was 0.98. Total score of DAD has been reported to be significantly and inversely correlated with level of global deterioration (Spearman’s rho = −0.89, p < .001; Mok et al., 2005). The Chinese version of the RMBPC (Fuh et al., 1999a) measures three domains of BPSD: memory-related problems, depression, and disruption problems. The 24-item scale assesses levels of BPSD on 5-point Likert scales from 0 (never occurs) to 4 (occurs daily or more often). The total score and each subscale score range from 0 to 96. The Cronbach’s α for the total score was 0.816, and the test–retest reliability was 0.89 (Fuh et al., 1999a). The RMBPC also comprises a subscale (RMBPCr, the Reaction scale of RMBPC) to measure caregivers’ reactions to the PWD’s states. In this study, caregiver subjective burden was measured with the RMBPCr. The RMBPCr assesses the caregiver’s reaction (upset) to each BPSD listed in the RMBPC from 0 (not at all) to 4 (extremely), yielding a total reaction score ranging from 0 to 96. The convergent validity of the scale was also satisfactory (Fuh et al., 1999a; 1999b). SOCIAL SUPPORT
The caregiver’s perceived social support was measured with the Chinese version of the Medical Outcome Study Social Support Survey (MOS-SSS; Shyu et al., 2006). The MOS-SSS includes four subscales which measure positive social interaction (four items), plus three types of social support: (a) emotional and informational (eight items); (b) tangible (4 items); and (c) affectionate (3 items). Each item is rated on a 5-point scale of 1 (none of the time) to 5 (all of the time). The total score of MOS-SSS ranges from 0 to 100. Higher scores indicate more perceived social support. All Cronbach’s α for the Chinese version of the scale were over 0.80, and the concurrent validity was also satisfactory (Shyu et al., 2006). C A R E G I V E R S E L F - E FFI C A C Y
Caregiver self-efficacy was measured with the 27-item Self-Efficacy Questionnaire for Chinese Family Caregivers (SEQCFC) developed by the authors (Zhang et al., 2012; 2013b). The questionnaire contains five domains of caregiver self-efficacy: (a) gathering information about treatment, symptoms, and health care (GI subscale, four items); (b) obtaining support (OS subscale,
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six items); (c) responding to behavior disturbances (RBD subscale, seven items); (d) managing the household, personal and medical care (MHPMC subscale, four items); and (e) managing distress associated with caregiving (MDC subscale, six items). The scores of total scale and subscale scores are rated as a percentage of 0% (“cannot do at all”) to 100% (“certainly can do”). Higher scores indicate a stronger sense of caregiver selfefficacy. The scale was reliable: all Cronbach’s α were over 0.80, the 4-week test–retest reliabilities ranged from 0.64 to 0.85.Convergent validity was also acceptable (Zhang et al., 2013b). Data Analysis In accord with the guidelines of Baron and Kenny (1986), we performed multiple regression analyses to test the hypothesized moderation (Figure 1) and mediation effects (Figure 2). To test the moderation effect of caregiver self-efficacy, the following regression equations were computed: (a) subjective burden as measured by RMBPCr, regressed on dementia–impairment variables (total scores of MMSE, RMBPC and DAD); and (b) social support (total score of MOS-SSS) (Figure 1, path a), on caregiver self-efficacy (total score of SEQCFC) (Figure 1, path b). If either BPSD or social support was a predictor of subjective burden, subjective burden would regress on the interaction of the corresponding predictor and caregiver self-efficacy (Figure 1, path c). As Baron and Kenny (1986) pointed out, the mediation effect is identified when predictors significantly associate with both the mediator (Figure 2, path a) and outcome (Figure 2, path c), and when the mediator significantly influences the outcome (Figure 2, path b). We applied hierarchical multiple regression analysis to test the mediation effect of caregiver selfefficacy (Figure 2, path c and c ). The mediation effect occurred if a reduced effect of the predictor on subjective burden was observed when caregiver self-efficacy entered the equation (Figure 2, path c ). Sobel tests (1986) were conducted to test the significance of the mediation effects. Prior to the analysis, normality, linearity, and homoscedasticity were tested and ensured, as was the absence of multicollinearity. All analyses were conducted using SPSS 16.0.
Results Descriptive statistics Table 1 shows the means of other variables. Measures relevant to PWDs’ are cognitive (MMSE) deficits, physical impairment (DAD), and
Table 1. Descriptive statistics for MMSE, DAD, RMBPC, MOS-SSS, caregiver self-efficacy, and mental health VARIABLES
MEAN
SD
......................................................................................................................................................
Care recipient (n = 137) MMSE DAD (%) RMBPC Caregiver (n = 137) Social support (MOS-SSS) Subjective burden (RMBPCr) Caregiver self-efficacy (SEQCFC)
13.88 60.04 27.69
8.57 31.73 13.93
47.03 14.06 67.58
20.42 13.41 16.05
Abbreviations: MMSE, Mini-Mental Status Examination; DAD, Disability Assessment in Dementia; RMBPC, Revised Memory and Behavior Problems Checklist; MOS-SSS, Medical Outcome Study Social Support Survey; RMBPCr, Reaction Subscale of RMBPC; SEQCFC, Self-Efficacy Questionnaire for Chinese Family Caregivers.
BPSD (RMBPC). Caregiver variables are social support (MOS-SSS), self-efficacy (SEQCFC), and subjective burden (RMBPCr). Moderation effects To meet the assumptions for the regression analyses, DAD was square-root transformed prior to the regression analysis. The results of moderation effect testing indicated that the composite influence of dementia-related impairments and social support was significant on caregiver subjective burden, explaining 63% of the variance in subjective burden scores (RMBPCr), F (4,136) = 58.552, p < .001, (Figure 1, path a). BPSD (RMBPC; β = 0.85, p < .001) and caregiver social support (MOSSSS; β = −.12, p = .013) had significant and contrary influences on subjective burden. Caregiver self-efficacy (SEQCFC), the potential moderator, significantly and inversely influenced subjective burden (β = −.40, p < .001), accounting for 15% of the variance in subjective burden, F (1,136) = 25.280, p < .001 (Figure 1, path b). As each interacted predictor significantly influenced subjective caregiver burden (interaction of RMBPC and SEQCFC: β = −.65, p < .001; interaction of MOS-SSS and SEQCFC: β = 1.08, p = .013), caregiver self-efficacy demonstrated moderation effects on impact of RMBPC on subjective caregiver burden [interaction of RMBPC and SEQCFC: F (5,136) = 67.417, p < .001)] (Figure 3) and on the influence of social support on subjective caregiver burden (Figure 4), respectively [interaction of MOS-SSS and SEQCFC: F (3,136) = 11.331, p < .001)]. In addition, the results showed that RMBPC and MOS-SSS also have a moderating effect on the influence of caregiver self-efficacy on subjective burden.
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Figure 3. Output model: caregiver self-efficacy moderating BPSD and caregiver subjective burden.
Figure 4. Output model: caregiver self-efficacy moderating social support and caregiver subjective burden.
Mediation effects Tables 2 and 3 present the results of mediation effect testing. Table 2 shows that the composite influence of dementia-related impairment and social support variables on caregiver self-efficacy was significant, accounting for 9.0% of the variance in SEQCFC, F (4,136) = 4.240, p = .003). BPSD (RMBPC; β = −.20, p = .045) and social support (MOS-SSS; β = .30, p = .001) were two significant predictors of caregiver self-efficacy. In the hierarchical multiple regression analysis (Table 3), the dementia-related impairments (MMSE, DAD, and RMBPC) entered as the first group of predictors, social support (MOSSSS) entered as the second group of predictors, and caregiver self-efficacy entered as the third group of predictors. The results showed that the compound influence of all predictors was significant on subjective burden, F (5,136) = 59.501, p < .001. After adjusting for the influence of dementiarelated impairments and social support, caregiver self-efficacy accounted for significant portions of subjective burden variance (β = −.25, ΔR2 = .06, p < .001); the β value of RMBPC was reduced from 0.85 (p < .001) to 0.80 (p < .001); and the β value of MOS-SSS was significantly increased from −0.12 (p = .035) to −0.04 (p = .419), indicating a full mediation effect of
caregiver self-efficacy between social support and subjective burden (Figure 5). But the results of Sobel tests (test statistic = 1.880, p = .06) showed caregiver self-efficacy had a borderline and partial mediation effect between the relationship of BPSD and subjective burden.
Discussion Our study was an empirical exploration of both patient and situational influences on caregiver outcomes, adapted from Bandura’s self-efficacy theory. We found links of caregiver self-efficacy to dementia-related impairments, social support, and subjective burden. Of all the dementiarelated impairments, degree of severity of BPSD was a primary factor impairing caregiver selfefficacy. Spouse CGs who perceived more social support reported stronger confidence in overcoming caregiving impediments. CGs with higher self-efficacy reported less subjective burden. The findings confirmed the findings of our previous work (Zhang et al., 2013b) and related studies in terms of self-efficacy in dementia caregivers (Zeiss et al., 1999; Gonyea et al., 2005). Our results showed that CGs’ social support significantly influenced their sense of subjective burden, after
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Table 2. Regression of dementia-related impairments and social support on caregiver self-efficacy (path a) DEPENDENT VARIABLE
(CAREGIVER
S E L F - E FFI C A C Y )
95% CI INDEPENDENT VARIABLES
β
SIG.
T
LB
UB
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Constant MMSE DAD RMBPC MOS- SSS R2 (adj.) F (4,136)
7.031 − 0.228 0.626 − 02.019 3.448
− 0.029 0.087 − 0.20 0.30
0.000 0.820 0.532 0.045 0.001
0.09 4.240
43.595 − 0.531 − 1.105 − 0.444 0.100
77.725 0.421 2.130 − 0.005 0.367
0.003
∗ P ࣘ .05; ∗∗ P ࣘ .01; ∗∗∗ P ࣘ .001 Abbreviations: 95% CI, 95% Confidence Interval for B; LB, Lower Bound; UB, Upper Bound.
Table 3. Hierarchical multiple regression of dementia-related impairments, social support, and caregiver self-efficacy on subjective caregiver burden (path c and c ) SUBJECTIVE CAREGIVER BURDEN
95% CI INDEPENDENT VARIABLES
ΔR2
ΔF
β
SIG.
T
LB
UB
.........................................................................................................................................................................................................................................................................................................................
Step 1 a MMSE DAD RMBPC Step 2 b MMSE DAD RMBPC Social support Step 3c MMSE DAD RMBPC Social support Caregiver self-efficacy R2 (adj.) F (5,136)
0.63
0.01
0.06
74.587∗∗∗
4.522∗
23.455∗∗∗
0.08 − 0.05 0.85
0.965 − 0.563 13.563
0.336 0.574 0.000
0.08 − 0.09 0.85 − 0.12
0.914 − 1.012 13.757 − 02.127
0.362 0.313 0.000 0.035
0.07 − 0.07 0.80 − 0.04 − 0.25
0.892 − 0.830 13.819 − 0.811 − 4.843 0.68 59.501∗∗∗
0.374 0.408 0.000 0.419 0.000
− 16.856 − 0.132 − 1.096 0.695 − 13.112 − 0.137 − 1.303 0.698 − 0.148 − 1.279 − 0.129 − 1.133 0.658 − 0.097 − 0.292
− 0.831 0.382 0.610 0.933 5.075 0.371 0.421 0.932 − 0.005 18.435 0.341 0.463 0.879 0.041 − 0.123
∗ p ࣘ .05; ∗∗ p ࣘ .01; ∗∗∗ p ࣘ .001 Abbreviations: 95% CI, 95% Confidence Interval for B; LB, Lower Bound; UB, Upper Bound. a, b Path c, influence of BPSD and social support on subjective caregiver burden. c Path c , mediation effects of caregiver self-efficacy on the influences of BPSD and social support on subjective caregiver burden.
controlling for PWD impairment. This finding is consistent with those of the previous studies (Pinquart and Sörensen, 2003b; Clay et al., 2008; Etters et al., 2008). However, the current study found that social support did not reduce the impact of PWDs’ impairment on the subjective burden variables. As the level of social support we found was not high, this result may indicate that the social support CGs perceived was too limited to man-
aging dementia-related impairments, particularly BPSD. The primary aim of the current study was to examine the mechanism by which caregiver selfefficacy influences subjective burden. According to Bandura (1997), an individual’s confidence in performing a specific task is influenced differentially by different situations. The dementia care literature highlights BPSD and social support as two primary
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Figure 5. Output model: mediating effect of caregiver self-efficacy on the relationships between social support and caregiver subjective burden.
situational factors. Our results also identified the indirect influence of social support on subjective burden through the mediation effect of caregiver self-efficacy. Au et al., (2009) reported a partial mediation effect of caregiver self-efficacy between social support and depressive symptoms. Our findings help confirm the association of high level of subject burden with more depressive symptoms (Pinquart and Sörensen, 2003a; 2003b). The full mediation effect we found may indicate the importance of caregiver self-efficacy in reducing CGs’ distress due to responding to BPSD. We also found a borderline and partial mediation effect of caregiver self-efficacy on the impact of BPSD on subjective burden. The majority of PWDs in the current study were at a mild stage of dementia, and this might help explain the low levels of BPSD and subjective burden. Therefore, the identified borderline effect maybe associated with the low levels of BPSD and corresponding subjective burden. Although the borderline effect requires further exploration, the present results suggested that enhancing caregiver self-efficacy may be a possible strategy that can help to reduce the impact of BPSD on CGs’ subjective burden. In addition, the buffering roles of caregiver selfefficacy identified in the current study indicate that the influences of BPSD and social support on subjective burden also depended on the extent of caregiver self-efficacy. The findings are potentially important contributions to caregiver self-efficacy research and can be interpreted based on Bandura’s theory. Confronted with severe BPSD or perceiving a certain degree of social support, CGs with a strong sense of caregiver self-efficacy tended to view the BPSD of care recipients as a challenge to overcome, or to use supportive resources to deal with caregiving challenges more effectively and efficiently. Such CGs consequently experienced less subjective burden. CGs with a weaker sense of caregiver self-efficacy might possibly have focused on past failure experiences, regarded the same severity of BPSD as threatening, perceived the same level of support with less
positive emotional responses to their caregiving role, and eventually felt a higher level of subjective burden. Therefore, the findings of our mediation and moderation exploration imply that enhancing caregiver self-efficacy can be an essential strategy in developing intervention to reduce CGs’ subjective burden. Since this investigation was an initial study conducted in mainland China on possible buffering and mediating roles of caregiver self-efficacy on the influences of BPSD and social support on subjective burden, some limitations should be noted; those elements suggest further studies. The low levels of BPSD and subjective burden and the borderline and partial mediation effect of caregiver self-efficacy between BPSD and subjective burden were possibly associated with the single recruitment centre used in the current study. Thus, further multicentre studies would be beneficial. Further, the subjective burden measure used in this study may not have assessed a broad enough scope of CG response. The Reaction Scale of Revised Memory and Behavioral Problem Checklist (RMBPCr) used in the current study mainly focused on subjective burden specifically related to BPSD. Hence, the subjective burden related to other aspects of dementia-related impairments (cognitive impairment and disability) possibly may not have been assessed directly or adequately. This limitation suggests that subjective burden instruments used in future investigations should reflect caregivers’ reactions to all main impairments of care recipients. In addition, in future studies, a larger sample size would facilitate the exploration of more complicated relationships among the conceptual constructs. Future studies will also explore the influences of socioeconomic and demographic variables on CGs’ self-efficacy and subjective burden because of the focus of this study. Lastly, a cross-sectional design with degree of impairment as a variable could be useful and might be more practical, a longitudinal design, however, could explore the possible influence of the stages of the dementia trajectory on caregiver self-efficacy and subjective
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burden. Moreover, longitudinal studies could also clarify the directionality of the identified effects during this trajectory. Nonetheless, the data presented here help elucidate the important role of caregiver self-efficacy in the paths of the two external factors (BPSD and social support), which influence subjective burden. A population-based investigation (Zhang et al., 2004) conducted in four large cities of China (Beijing, Xian, Shanghai, and Chengdu) reported that over one-third of dementia CGs was spouses in mainland China. Considering factors such as China’s “one child” policy, increasing life expectancy, and rapid growth of the aged population in the country, it is a fairly safe prediction that increasing numbers of old people with degenerative chronic diseases such as dementia will have to depend mainly on the care from their aged and frail spouses. Therefore, our study also contributes to the research on this population in China. The findings of our study imply that enhancing caregiver self-efficacy—particularly self-efficacy for symptom management—can be considered an integral part of interventions to reduce the subjective burden of an aging, and progressively frailer, population in China.
Conflict of interest declaration There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. This work is not currently under review by another journal and has not been previously published elsewhere either in printed or electronic form. All authors have contributed significantly, and all authors are in agreement with the content of the manuscript. This study was approved by the designated hospital and Human Research Ethics Committee of Queensland University of Technology (0900000393).
Description of authors’ roles Dr. Shu Ying Zhang designed the study, conducted data collection and data analysis, and wrote the manuscript. Dr Helen Edwards and Dr. Patsy Yates supervised the study design and provided the suggestion for data collection. Dr. Qi Hao Guo supervised the study design and data collection and provided fund for data collection. Dr. Chun Bo Li supervised the study design, provided the suggestion for data collection, data analysis, and supervised the write-up.
Acknowledgment The author wishes to thank all the participants and the cooperation of the staff at the Geriatric Psychiatry Department of Shanghai Mental Health Centre and the Neurological Institution of Shanghai Huashan Hospital. We also appreciate Dr. GukHee Suh and peer reviewers for their constructive comments. This work was funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry to Dr. Shuying Zhang.
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Shyu, Y. I. L., Tang, W. R., Liang, J. and Weng, L. J. (2006). Psychometric testing of the Social Support Survey on a Taiwanese sample. Nursing Research, 55, 411– 417. Sobel, M E. (1986) Some new results on indirect effects and their standard errors in covariance structure. Sociological Methodology, 16, 159–186. Steffen, A. M., McKibbin, C., Zeiss, A. M., Gallagher-Thompson, D. and Bandura, A. (2002). The revised scale for caregiving self-efficacy: reliability and validity studies. The Journals of Gerontology, 57B, 74–86. Zeiss, A., Gallagher-Thompson, D., Lovett, S., Rose, J. and McKibbin, C. (1999). Self-efficacy as a mediator of caregiver coping: development and testing of an assessment model. Journal of Clinical Geropsychology, 5, 221–230. Zhang, S. Y., Edwards, H., Yates, P., Elder, R. and Guo, Q. H. (2012). Development of self-efficacy questionnaire for Chinese family caregivers. International Journal of Mental Health Nursing, 21, 358–365. Zhang, S. Y., Edwards, H., Yates, P., Guo, Q. H. and Li, C. B. (2013a). Partial mediation role of self-efficacy between positive social interaction and mental health in family caregivers for dementia patients in Shanghai. PLOS One, 8. Zhang, S. Y., Edwards, H., Yates, P., Ruth, E. and Guo, Q. H. (2013b). Preliminary reliability and validity testing of a self-efficacy questionnaire for Chinese family caregivers. Aging & Mental Health, 17, 630–637. Zhang, S. Y., Edwards, H., Yates, P., Li, C. B and Guo, Q. H. (2014). Self-efficacy partially mediates between social support and health-related quality of life in family caregivers for dementia patients in Shanghai. Dement Geriatric Cognitive Disorders, 37, 34–44. Zhang, Z. X. et al. (2004) A caregiver survey in Beijing, Xian, Shanghai and Chengdu: Health service status for the elderly with dementia. Acta Academiae Medicinae Sinicae, 26, 116–121.
Self-efficacy moderation and mediation roles on BPSD and social support influences on subjective caregiver burden in Chinese spouse caregivers of dementia patients ...........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Shuying Zhang,1 Qihao Guo,2 Helen Edwards,3 Patsy Yates3 and Chunbo Li4 1
Tongji University School of Medicine, Shanghai, China Department of Neurology and Institute of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China 3 Institute of Health and Biomedical Innovation, Queensland University of Technology, Queensland, Australia 4 Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Institute of Mental Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2
ABSTRACT
Background: This study aims to explore moderation and mediation roles of caregiver self-efficacy between subjective caregiver burden and (a) behavioral and psychological symptoms (BPSD) of dementia; and (b) social support. Methods: A cross-sectional study with 137 spouse caregivers of dementia patients was conducted in Shanghai. We collected demographic information for the caregiver–patient dyads, as well as information associated with dementia-related impairments, caregiver social support, caregiver self-efficacy, and SF-36. Results: Multiple regression analysis showed that caregiver self-efficacy was a moderator both between BPSD and subjective caregiver burden, and social support and subjective caregiver burden. Results also showed a partial mediation effect of caregiver self-efficacy on the impact of BPSD on subjective caregiver burden, and a mediation effect of social support on subjective caregiver burden. Caregiver self-efficacy and subjective burden significantly influenced BPSD and social support. Conclusion: Caregiver self-efficacy played an important role in the paths by which the two factors influenced subjective burden. Enhancing caregiver self-efficacy for symptom management (particularly BPSD) can be an essential strategy for determining interventions to support dementia caregivers in China, and possibly in other countries. Key words: caregiver self-efficacy, BPSD, dementia, family caregiver, social support, subjective caregiver burden
Introduction Self-efficacy is a cognitive construct that refers to an individual’s belief in his or her capacity to successfully accomplish a specific task in confronting different barriers (Bandura, 1997). Self-efficacy has received increasing attention in the literature of family caregiving for people with dementia (Pinquart and Sörensen, 2003a; 2007; Au et al., 2009; Rabinowitz et al., 2009). Many studies showed that compared to other dementia-related impairments including cognitive and physical impairment, the behavioral and psychological symptoms of dementia (BPSD; Finkel et al., 1997) were the primary barriers Correspondence should be addressed to: Chunbo Li, Shanghai Mental Health Center, 600 Wan Ping Nan Rd, Shanghai 200030, China. Phone: 86-213477 3243; Fax: 86-21-6438 7986. Email: [email protected] Received 22 Oct 2013; revision requested 10 Mar 2014; revised version received 7 Apr 2014; accepted 1 May 2014. First published online 16 June 2014.
impairing dementia caregivers’ (CGs) confidence in managing care (Zeiss et al., 1999; Pinquart and Sörensen, 2003a; Depp et al., 2005); while social support was the resource enhancing CGs’ sense of self-efficacy (Zeiss et al., 1999; Steffen et al., 2002; Gottlieb and Rooney, 2003; Depp et al., 2005; Au et al., 2009). Other data show that a stronger sense of caregiver self-efficacy positively influenced CGs’ own health-related outcomes, such as reduced subjective burden (Pinquart and Sörensen, 2003a; 2003b; 2007), fewer negative emotions (Au et al., 2009; Rabinowitz et al., 2009), and better physical health (Pinquart and Sörensen, 2003a; 2007). Compared to the extensive studies on the direct influence that caregiver self-efficacy exerts on variables (such as BPSD and social support) related to caregiving situations and CGs’ health outcomes, research exploring indirect effects of self-efficacy has remained limited, particularly the
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Figure 1. Hypothesized moderation effects of caregiver self-efficacy on the relationships between the behavioral and psychological symptoms of dementia (BPSD)/social support and caregiver subjective burden.
ways in which CG self-efficacy might influence associations of BPSD and social support with CGs’ health-related outcomes (e.g., depression, anxiety, subjective burden, and quality of life). According to Bandura (1997), self-efficacy influences both the strategies individuals envision for reaching their goals and the efficiency and effectiveness of their problem-solving. When confronting the same situation (e.g., responding to the same severity of BPSD or perceiving the same level of social support), individuals with strong self-efficacy may regard the condition as a challenge, deal with problems using more effective strategies, and exert themselves to overcome challenges. On the other hand, individuals with a weak sense of self-efficacy doubt their capability to master the task, tend to give up easily, and experience failure more readily. Consequently, those with low self-efficacy for managing stressors may develop negative emotions, such as anxiety and depression. As an example, Rabinowitz et al., (2009) found a moderating role for caregiver self-efficacy between the relationship of BPSD and CGs’ depressive symptoms. Social support has been regarded as another situational factor influencing caregiver self-efficacy and health-related outcomes. Relatively few studies have explored the moderation effect of caregiver self-efficacy on the relationship between social support and CGs’ health-related outcomes. In addition to the research exploring that moderation effect, Au et al., (2009) reported that caregiver self-efficacy was the partial mediator of the relationship between social support and CGs’ depressive symptoms. Our previous study (Zhang et al., 2014) also found a partial mediating effect of caregiver self-efficacy on the influence of social support on CGs’ HRQoL. However, mediation effects of caregiver self-efficacy on the impact of BPSD on CGs’ health-related outcomes have not received much research attention. The studies on moderation or mediation effects have mainly
focused on the links of BPSD and social support with CGs’ depressive symptoms (Au et al., 2009; Rabinowitz et al., 2009) or mental health (Zhang et al., 2013a). In the dementia literature, subjective burden, which refers to the subjective impacts of caregiving on CGs (Pearlin et al., 1990), was an important outcome variable significantly correlated with CGs’ negative emotions, including depression and anxiety (Pinquart and Sörensen, 2003a; 2003b; Cuijpers, 2005; Cooper et al., 2007). Again, however, existing research literature on these relationships is sparse. The moderation and mediation effects of caregiver self-efficacy on this negative emotional outcome need further exploration. Moreover, given differences in cultural attitudes toward care for the elderly, it seems reasonable that the relationships among CG selfefficacy, BPSD, social support, and subjective burden may have a special culturally conditioned character in Chinese culture. Therefore, the current study examined (a) the moderating role of caregiver self-efficacy between BPSD and subjective caregiver burden (Figure 1); (b) the moderating role of caregiver self-efficacy between social support and subjective caregiver burden (Figure 1); and (c) the mediation effects of caregiver self-efficacy on the influences of BPSD and social support on subjective caregiver burden (Figure 2).
Methods Participants We screened an initial sample of 196 caregivers (Zhang et al., 2013b), recruited from the neurological outpatient department of Shanghai Huashan Hospital, to arrive at a sample of 137 spouse CGs (79 wives) who provided the data in the present study. The criterion for inclusion was that the spouse provided most of the care for the patient
Self-efficacy moderation and mediation roles
Figure 2. Hypothesized mediating effects of caregiver self-efficacy on the relationships between the behavioral and psychological symptoms of dementia (BPSD), social support, and caregiver subjective burden.
with dementia (PWD, diagnosed using DSM-IV criteria). Spouses who were simultaneously caring for other relatives with a chronic medical condition were excluded. Permission to use the standard instruments was obtained from the original authors and ethical approval to conduct the study was also obtained by the designated institution prior to the survey. The procedure for recruitment and data collection was described in a previous article (Zhang et al., 2013a). Spouses simultaneously caring for any other relatives with a chronic medical condition were excluded. Thus, 137 spouses CGs completed the survey. Among the 137 participants, 131 participants completed the questionnaires at the hospital, and six at home; the latter were conducted up to 10 days after the hospital visit. The major reason for completing the questionnaires at home was the fatigue associated with doing these on the same day or inconvenience of the transportation to the hospital if participants were selected another day. The mean age of PWDs was 71.0 years old (SD = 8.28), and that of spouse CGs was 69.9 (SD = 8.97) years old. PWDs’ stage of dementia was obtained from their medical records. Among the PWDs, 72 (52.6%) were diagnosed with mild stage of dementia, 25 (18.2%) were at a moderate stage, and 40 (29.2%) were at a severe stage. Measures DEMENTIA-RELATED IMPAIRMENTS AND SUBJECTIVE CAREGIVER BURDEN
The Mini-Mental Status Examination (MMSE) scores were obtained from the PWDs’ medical records. Levels of physical impairment and BPSD were assessed with the Chinese version of the Disability Assessment in Dementia (DAD; Mok et al., 2005) and the Revised Memory and Behavior Problems Checklist (RMBPC; Fuh et al., 1999a), respectively. RMBPC data were reported by the spouses. The DAD assesses instrumental activities of daily living (DAD–IADLs, 25 items) and activities of daily living (DAD–ADLs, 22 items) during the most recent 2 weeks. The total scores on the DAD and on each of the two
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subscales were rated as a percentage of total possible score, with higher scores indicating better physical functioning. The psychometric properties of DAD were satisfactory: the Cronbach’s α for the total score was 0.91, the test–retest reliability was 0.99, and the interrater reliability was 0.98. Total score of DAD has been reported to be significantly and inversely correlated with level of global deterioration (Spearman’s rho = −0.89, p < .001; Mok et al., 2005). The Chinese version of the RMBPC (Fuh et al., 1999a) measures three domains of BPSD: memory-related problems, depression, and disruption problems. The 24-item scale assesses levels of BPSD on 5-point Likert scales from 0 (never occurs) to 4 (occurs daily or more often). The total score and each subscale score range from 0 to 96. The Cronbach’s α for the total score was 0.816, and the test–retest reliability was 0.89 (Fuh et al., 1999a). The RMBPC also comprises a subscale (RMBPCr, the Reaction scale of RMBPC) to measure caregivers’ reactions to the PWD’s states. In this study, caregiver subjective burden was measured with the RMBPCr. The RMBPCr assesses the caregiver’s reaction (upset) to each BPSD listed in the RMBPC from 0 (not at all) to 4 (extremely), yielding a total reaction score ranging from 0 to 96. The convergent validity of the scale was also satisfactory (Fuh et al., 1999a; 1999b). SOCIAL SUPPORT
The caregiver’s perceived social support was measured with the Chinese version of the Medical Outcome Study Social Support Survey (MOS-SSS; Shyu et al., 2006). The MOS-SSS includes four subscales which measure positive social interaction (four items), plus three types of social support: (a) emotional and informational (eight items); (b) tangible (4 items); and (c) affectionate (3 items). Each item is rated on a 5-point scale of 1 (none of the time) to 5 (all of the time). The total score of MOS-SSS ranges from 0 to 100. Higher scores indicate more perceived social support. All Cronbach’s α for the Chinese version of the scale were over 0.80, and the concurrent validity was also satisfactory (Shyu et al., 2006). C A R E G I V E R S E L F - E FFI C A C Y
Caregiver self-efficacy was measured with the 27-item Self-Efficacy Questionnaire for Chinese Family Caregivers (SEQCFC) developed by the authors (Zhang et al., 2012; 2013b). The questionnaire contains five domains of caregiver self-efficacy: (a) gathering information about treatment, symptoms, and health care (GI subscale, four items); (b) obtaining support (OS subscale,
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six items); (c) responding to behavior disturbances (RBD subscale, seven items); (d) managing the household, personal and medical care (MHPMC subscale, four items); and (e) managing distress associated with caregiving (MDC subscale, six items). The scores of total scale and subscale scores are rated as a percentage of 0% (“cannot do at all”) to 100% (“certainly can do”). Higher scores indicate a stronger sense of caregiver selfefficacy. The scale was reliable: all Cronbach’s α were over 0.80, the 4-week test–retest reliabilities ranged from 0.64 to 0.85.Convergent validity was also acceptable (Zhang et al., 2013b). Data Analysis In accord with the guidelines of Baron and Kenny (1986), we performed multiple regression analyses to test the hypothesized moderation (Figure 1) and mediation effects (Figure 2). To test the moderation effect of caregiver self-efficacy, the following regression equations were computed: (a) subjective burden as measured by RMBPCr, regressed on dementia–impairment variables (total scores of MMSE, RMBPC and DAD); and (b) social support (total score of MOS-SSS) (Figure 1, path a), on caregiver self-efficacy (total score of SEQCFC) (Figure 1, path b). If either BPSD or social support was a predictor of subjective burden, subjective burden would regress on the interaction of the corresponding predictor and caregiver self-efficacy (Figure 1, path c). As Baron and Kenny (1986) pointed out, the mediation effect is identified when predictors significantly associate with both the mediator (Figure 2, path a) and outcome (Figure 2, path c), and when the mediator significantly influences the outcome (Figure 2, path b). We applied hierarchical multiple regression analysis to test the mediation effect of caregiver selfefficacy (Figure 2, path c and c ). The mediation effect occurred if a reduced effect of the predictor on subjective burden was observed when caregiver self-efficacy entered the equation (Figure 2, path c ). Sobel tests (1986) were conducted to test the significance of the mediation effects. Prior to the analysis, normality, linearity, and homoscedasticity were tested and ensured, as was the absence of multicollinearity. All analyses were conducted using SPSS 16.0.
Results Descriptive statistics Table 1 shows the means of other variables. Measures relevant to PWDs’ are cognitive (MMSE) deficits, physical impairment (DAD), and
Table 1. Descriptive statistics for MMSE, DAD, RMBPC, MOS-SSS, caregiver self-efficacy, and mental health VARIABLES
MEAN
SD
......................................................................................................................................................
Care recipient (n = 137) MMSE DAD (%) RMBPC Caregiver (n = 137) Social support (MOS-SSS) Subjective burden (RMBPCr) Caregiver self-efficacy (SEQCFC)
13.88 60.04 27.69
8.57 31.73 13.93
47.03 14.06 67.58
20.42 13.41 16.05
Abbreviations: MMSE, Mini-Mental Status Examination; DAD, Disability Assessment in Dementia; RMBPC, Revised Memory and Behavior Problems Checklist; MOS-SSS, Medical Outcome Study Social Support Survey; RMBPCr, Reaction Subscale of RMBPC; SEQCFC, Self-Efficacy Questionnaire for Chinese Family Caregivers.
BPSD (RMBPC). Caregiver variables are social support (MOS-SSS), self-efficacy (SEQCFC), and subjective burden (RMBPCr). Moderation effects To meet the assumptions for the regression analyses, DAD was square-root transformed prior to the regression analysis. The results of moderation effect testing indicated that the composite influence of dementia-related impairments and social support was significant on caregiver subjective burden, explaining 63% of the variance in subjective burden scores (RMBPCr), F (4,136) = 58.552, p < .001, (Figure 1, path a). BPSD (RMBPC; β = 0.85, p < .001) and caregiver social support (MOSSSS; β = −.12, p = .013) had significant and contrary influences on subjective burden. Caregiver self-efficacy (SEQCFC), the potential moderator, significantly and inversely influenced subjective burden (β = −.40, p < .001), accounting for 15% of the variance in subjective burden, F (1,136) = 25.280, p < .001 (Figure 1, path b). As each interacted predictor significantly influenced subjective caregiver burden (interaction of RMBPC and SEQCFC: β = −.65, p < .001; interaction of MOS-SSS and SEQCFC: β = 1.08, p = .013), caregiver self-efficacy demonstrated moderation effects on impact of RMBPC on subjective caregiver burden [interaction of RMBPC and SEQCFC: F (5,136) = 67.417, p < .001)] (Figure 3) and on the influence of social support on subjective caregiver burden (Figure 4), respectively [interaction of MOS-SSS and SEQCFC: F (3,136) = 11.331, p < .001)]. In addition, the results showed that RMBPC and MOS-SSS also have a moderating effect on the influence of caregiver self-efficacy on subjective burden.
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Figure 3. Output model: caregiver self-efficacy moderating BPSD and caregiver subjective burden.
Figure 4. Output model: caregiver self-efficacy moderating social support and caregiver subjective burden.
Mediation effects Tables 2 and 3 present the results of mediation effect testing. Table 2 shows that the composite influence of dementia-related impairment and social support variables on caregiver self-efficacy was significant, accounting for 9.0% of the variance in SEQCFC, F (4,136) = 4.240, p = .003). BPSD (RMBPC; β = −.20, p = .045) and social support (MOS-SSS; β = .30, p = .001) were two significant predictors of caregiver self-efficacy. In the hierarchical multiple regression analysis (Table 3), the dementia-related impairments (MMSE, DAD, and RMBPC) entered as the first group of predictors, social support (MOSSSS) entered as the second group of predictors, and caregiver self-efficacy entered as the third group of predictors. The results showed that the compound influence of all predictors was significant on subjective burden, F (5,136) = 59.501, p < .001. After adjusting for the influence of dementiarelated impairments and social support, caregiver self-efficacy accounted for significant portions of subjective burden variance (β = −.25, ΔR2 = .06, p < .001); the β value of RMBPC was reduced from 0.85 (p < .001) to 0.80 (p < .001); and the β value of MOS-SSS was significantly increased from −0.12 (p = .035) to −0.04 (p = .419), indicating a full mediation effect of
caregiver self-efficacy between social support and subjective burden (Figure 5). But the results of Sobel tests (test statistic = 1.880, p = .06) showed caregiver self-efficacy had a borderline and partial mediation effect between the relationship of BPSD and subjective burden.
Discussion Our study was an empirical exploration of both patient and situational influences on caregiver outcomes, adapted from Bandura’s self-efficacy theory. We found links of caregiver self-efficacy to dementia-related impairments, social support, and subjective burden. Of all the dementiarelated impairments, degree of severity of BPSD was a primary factor impairing caregiver selfefficacy. Spouse CGs who perceived more social support reported stronger confidence in overcoming caregiving impediments. CGs with higher self-efficacy reported less subjective burden. The findings confirmed the findings of our previous work (Zhang et al., 2013b) and related studies in terms of self-efficacy in dementia caregivers (Zeiss et al., 1999; Gonyea et al., 2005). Our results showed that CGs’ social support significantly influenced their sense of subjective burden, after
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Table 2. Regression of dementia-related impairments and social support on caregiver self-efficacy (path a) DEPENDENT VARIABLE
(CAREGIVER
S E L F - E FFI C A C Y )
95% CI INDEPENDENT VARIABLES
β
SIG.
T
LB
UB
.....................................................................................................................................................................................................................................................................
Constant MMSE DAD RMBPC MOS- SSS R2 (adj.) F (4,136)
7.031 − 0.228 0.626 − 02.019 3.448
− 0.029 0.087 − 0.20 0.30
0.000 0.820 0.532 0.045 0.001
0.09 4.240
43.595 − 0.531 − 1.105 − 0.444 0.100
77.725 0.421 2.130 − 0.005 0.367
0.003
∗ P ࣘ .05; ∗∗ P ࣘ .01; ∗∗∗ P ࣘ .001 Abbreviations: 95% CI, 95% Confidence Interval for B; LB, Lower Bound; UB, Upper Bound.
Table 3. Hierarchical multiple regression of dementia-related impairments, social support, and caregiver self-efficacy on subjective caregiver burden (path c and c ) SUBJECTIVE CAREGIVER BURDEN
95% CI INDEPENDENT VARIABLES
ΔR2
ΔF
β
SIG.
T
LB
UB
.........................................................................................................................................................................................................................................................................................................................
Step 1 a MMSE DAD RMBPC Step 2 b MMSE DAD RMBPC Social support Step 3c MMSE DAD RMBPC Social support Caregiver self-efficacy R2 (adj.) F (5,136)
0.63
0.01
0.06
74.587∗∗∗
4.522∗
23.455∗∗∗
0.08 − 0.05 0.85
0.965 − 0.563 13.563
0.336 0.574 0.000
0.08 − 0.09 0.85 − 0.12
0.914 − 1.012 13.757 − 02.127
0.362 0.313 0.000 0.035
0.07 − 0.07 0.80 − 0.04 − 0.25
0.892 − 0.830 13.819 − 0.811 − 4.843 0.68 59.501∗∗∗
0.374 0.408 0.000 0.419 0.000
− 16.856 − 0.132 − 1.096 0.695 − 13.112 − 0.137 − 1.303 0.698 − 0.148 − 1.279 − 0.129 − 1.133 0.658 − 0.097 − 0.292
− 0.831 0.382 0.610 0.933 5.075 0.371 0.421 0.932 − 0.005 18.435 0.341 0.463 0.879 0.041 − 0.123
∗ p ࣘ .05; ∗∗ p ࣘ .01; ∗∗∗ p ࣘ .001 Abbreviations: 95% CI, 95% Confidence Interval for B; LB, Lower Bound; UB, Upper Bound. a, b Path c, influence of BPSD and social support on subjective caregiver burden. c Path c , mediation effects of caregiver self-efficacy on the influences of BPSD and social support on subjective caregiver burden.
controlling for PWD impairment. This finding is consistent with those of the previous studies (Pinquart and Sörensen, 2003b; Clay et al., 2008; Etters et al., 2008). However, the current study found that social support did not reduce the impact of PWDs’ impairment on the subjective burden variables. As the level of social support we found was not high, this result may indicate that the social support CGs perceived was too limited to man-
aging dementia-related impairments, particularly BPSD. The primary aim of the current study was to examine the mechanism by which caregiver selfefficacy influences subjective burden. According to Bandura (1997), an individual’s confidence in performing a specific task is influenced differentially by different situations. The dementia care literature highlights BPSD and social support as two primary
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Figure 5. Output model: mediating effect of caregiver self-efficacy on the relationships between social support and caregiver subjective burden.
situational factors. Our results also identified the indirect influence of social support on subjective burden through the mediation effect of caregiver self-efficacy. Au et al., (2009) reported a partial mediation effect of caregiver self-efficacy between social support and depressive symptoms. Our findings help confirm the association of high level of subject burden with more depressive symptoms (Pinquart and Sörensen, 2003a; 2003b). The full mediation effect we found may indicate the importance of caregiver self-efficacy in reducing CGs’ distress due to responding to BPSD. We also found a borderline and partial mediation effect of caregiver self-efficacy on the impact of BPSD on subjective burden. The majority of PWDs in the current study were at a mild stage of dementia, and this might help explain the low levels of BPSD and subjective burden. Therefore, the identified borderline effect maybe associated with the low levels of BPSD and corresponding subjective burden. Although the borderline effect requires further exploration, the present results suggested that enhancing caregiver self-efficacy may be a possible strategy that can help to reduce the impact of BPSD on CGs’ subjective burden. In addition, the buffering roles of caregiver selfefficacy identified in the current study indicate that the influences of BPSD and social support on subjective burden also depended on the extent of caregiver self-efficacy. The findings are potentially important contributions to caregiver self-efficacy research and can be interpreted based on Bandura’s theory. Confronted with severe BPSD or perceiving a certain degree of social support, CGs with a strong sense of caregiver self-efficacy tended to view the BPSD of care recipients as a challenge to overcome, or to use supportive resources to deal with caregiving challenges more effectively and efficiently. Such CGs consequently experienced less subjective burden. CGs with a weaker sense of caregiver self-efficacy might possibly have focused on past failure experiences, regarded the same severity of BPSD as threatening, perceived the same level of support with less
positive emotional responses to their caregiving role, and eventually felt a higher level of subjective burden. Therefore, the findings of our mediation and moderation exploration imply that enhancing caregiver self-efficacy can be an essential strategy in developing intervention to reduce CGs’ subjective burden. Since this investigation was an initial study conducted in mainland China on possible buffering and mediating roles of caregiver self-efficacy on the influences of BPSD and social support on subjective burden, some limitations should be noted; those elements suggest further studies. The low levels of BPSD and subjective burden and the borderline and partial mediation effect of caregiver self-efficacy between BPSD and subjective burden were possibly associated with the single recruitment centre used in the current study. Thus, further multicentre studies would be beneficial. Further, the subjective burden measure used in this study may not have assessed a broad enough scope of CG response. The Reaction Scale of Revised Memory and Behavioral Problem Checklist (RMBPCr) used in the current study mainly focused on subjective burden specifically related to BPSD. Hence, the subjective burden related to other aspects of dementia-related impairments (cognitive impairment and disability) possibly may not have been assessed directly or adequately. This limitation suggests that subjective burden instruments used in future investigations should reflect caregivers’ reactions to all main impairments of care recipients. In addition, in future studies, a larger sample size would facilitate the exploration of more complicated relationships among the conceptual constructs. Future studies will also explore the influences of socioeconomic and demographic variables on CGs’ self-efficacy and subjective burden because of the focus of this study. Lastly, a cross-sectional design with degree of impairment as a variable could be useful and might be more practical, a longitudinal design, however, could explore the possible influence of the stages of the dementia trajectory on caregiver self-efficacy and subjective
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burden. Moreover, longitudinal studies could also clarify the directionality of the identified effects during this trajectory. Nonetheless, the data presented here help elucidate the important role of caregiver self-efficacy in the paths of the two external factors (BPSD and social support), which influence subjective burden. A population-based investigation (Zhang et al., 2004) conducted in four large cities of China (Beijing, Xian, Shanghai, and Chengdu) reported that over one-third of dementia CGs was spouses in mainland China. Considering factors such as China’s “one child” policy, increasing life expectancy, and rapid growth of the aged population in the country, it is a fairly safe prediction that increasing numbers of old people with degenerative chronic diseases such as dementia will have to depend mainly on the care from their aged and frail spouses. Therefore, our study also contributes to the research on this population in China. The findings of our study imply that enhancing caregiver self-efficacy—particularly self-efficacy for symptom management—can be considered an integral part of interventions to reduce the subjective burden of an aging, and progressively frailer, population in China.
Conflict of interest declaration There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. This work is not currently under review by another journal and has not been previously published elsewhere either in printed or electronic form. All authors have contributed significantly, and all authors are in agreement with the content of the manuscript. This study was approved by the designated hospital and Human Research Ethics Committee of Queensland University of Technology (0900000393).
Description of authors’ roles Dr. Shu Ying Zhang designed the study, conducted data collection and data analysis, and wrote the manuscript. Dr Helen Edwards and Dr. Patsy Yates supervised the study design and provided the suggestion for data collection. Dr. Qi Hao Guo supervised the study design and data collection and provided fund for data collection. Dr. Chun Bo Li supervised the study design, provided the suggestion for data collection, data analysis, and supervised the write-up.
Acknowledgment The author wishes to thank all the participants and the cooperation of the staff at the Geriatric Psychiatry Department of Shanghai Mental Health Centre and the Neurological Institution of Shanghai Huashan Hospital. We also appreciate Dr. GukHee Suh and peer reviewers for their constructive comments. This work was funded by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry to Dr. Shuying Zhang.
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