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. Author manuscript; available in PMC: 2021 May 1.
Published in final edited form as: Aging Ment Health. 2018 Dec 29;24(5):774–783. doi: 10.1080/13607863.2018.1544221

Caregiving Centenarians: Cross-national Comparison in Caregiver-Burden between the United States and Japan

J Cho 1,2, T Nakagawa 3,4, P Martin 5, Y Gondo 6, L W Poon 7, N Hirose 8
PMCID: PMC6599484  NIHMSID: NIHMS1520290  PMID: 30596257

Abstract

Background and Objectives.

The personal distress associated with caring for a family member has been well documented; however, questions about the burden of caregiving for centenarians and cross-national differences in the caregiving context, remain unanswered.

Research Design and Methods.

This study includes reports by caregivers of 538 near-centenarians and centenarians in the U.S. and Japan: 234 from the Georgia Centenarian Study and 304 from the Tokyo Centenarian Study. Basic descriptive and multivariate regression analyses were conducted. Mean levels of caregiver burden and near-centenarian and centenarians’ characteristics (as predictors) for caregiver burden were compared between the U.S. and Japan. The near-centenarian and centenarians’ functional capacity and personality were assessed as predictors.

Results.

Differential predictive patterns in caregiver burden were found in the two groups. In the U.S., near-centenarian and centenarians’ agreeableness and conscientiousness were negatively associated with caregiver burden; whereas the near-centenarian and centenarians’ neuroticism and number of diseases were positively associated with caregiver burden. In Japan, the near-centenarian and centenarians’ activities of daily living, openness, and agreeableness were negatively associated with caregiving burden. Interaction effects between functional capacity and personality, on caregiver burden were observed only in the U.S. In the U.S., higher levels of agreeableness and openness significantly changed the level of caregiver burden associated with vision problems and a greater number of diseases.

Discussion and Implications.

Cross-national comparative predictors of caregiving burden between the two countries emphasized that caring for centenarians should be understood in the caregiving context, as well as the social context in the caregiving context.

Keywords: Centenarians, caregiver burden, cross-national comparisons, cultural context

Due to increases in life expectancy, the number of oldest-old adults, those who are over 80 years of age, is rapidly expanding in the worldwide population (United Nations, 2015). The number of oldest-old adults will rise globally from 126.5 million in 2015 to 446.6 million in 2050; moreover, globally, the number of centenarians is expected to rise to over 3.4 million by 2050 (United Nations, 2013). Many countries will encounter challenges in dealing with an increasing number of oldest-old. Compared to younger populations, a larger proportion of oldest old population is more likely to decline in physical and cognitive functioning, which will threaten independence of living in later life (Herrmann, Michel, & Robine, 2010). Formal long-term care may be an option; however, institutional or collective housing is not yet commonly considered in many countries (Herrmann et al., 2010). Furthermore, many older adults prefer to remain in their own home as long as possible rather than move to a care facility.

Families (spouses, children, and child-in-laws) providing informal care for their aging parents is a common alternative. However, family caregiving has been associated with chronic stress and higher levels of caregiver burden, which may lead to physical and mental issues (Family Caregiver Alliance, 2012; Alzheimer’s Association, 2018). Earlier studies have shown various risk factors associated with caregiver burden, such as demographic characteristics of caregivers, and functional status and personality of care recipients. For example, level of caregiver burden was more likely to increase as the care-recipients’ physical or cognitive functioning declined (Pinquart & Sörensen, 2007). Additionally, not only were personality traits (e.g., agreeableness, openness) of care recipients related to caregiver burden, the personality of care recipients was also shown to affect the interaction with their caregivers (Löckenhoff, Duberstein, Friedman, & Costa, 2011; Robins, Caspi, & Moffitt, 2000). In terms of caregivers’ characteristics, their age, relationship to the care-recipient (spouse or children), and whether they were in co-residence were also strong correlates to caregivers’ health (Pinquart & Sörensen, 2007).

Theoretical Framework

While personal factors of caregivers and care recipients have been readily explored, another line of research emphasized the role of contextual factors. A conceptual model, the stress process model (SPM) suggested by Pearlin and colleagues (1990), emphasized that contextual factors (e.g., access to resources) related to the caregiver role in the context of caregiving for older adults with Alzheimer’s disease. Pinquart and Sörensen (2005) examined diverse racial or ethnic groups for whom available resources, the use of coping strategies, and differing levels of stressors may have contributed to caregiver burden. Emphasizing ethnicity as culture, the sociocultural stress and coping model framed cultural values on the dimension of individualism–familism as a framework for understanding caregiver stress and coping processes (Aranda & Knight, 1997; Knight et al., 2002; Knight & Sayegh, 2010). Specifically, this model hypothesized that “higher levels of familism would result in the appraisal of caregiving for family members as less burdensome, as it would reflect an underlying deep rooted desire to provide care for their loved ones” (Knight & Sayegh, 2010, p. 7).

In addition to the sociocultural stress and coping model, the multiaxial model of coping explained different attitudes toward caregiving behaviors in two cultures (Hobfoll, 1998; 2001). The multiaxial model suggested that the social and cultural context of coping plays an important role in the individual’s relationship to their families, religious institutions, employment organizations, charitable institutions, neighborhoods, and ethnic groups (Hobfoll, 2001; Kuo, 2011). According to this model, three dimensions of coping (i.e., passive-active, prosocial-antisocial, and direct-indirect dimensions) could be determined by the following factors: (a) objective factors based on the individual’s accurate interpretation; (b) objective factors based on culturally shared biases within a culture; (c) objective factors based on familial norms and rules; (d) illusions based on individual, familial, and cultural biases; and (e) illusions based on personal biases (Kuo, 2011, p. 1087). This perspective may also provide a theoretical background to understanding caregiving contexts in specific cultures and/or societies. Although a number of prior studies have focused on cultural differences in a society (e.g., Asian Americans vs. Caucasians or African Americans vs. Caucasians) or on a comparison of cultures in a caregiving context (e.g., Sayegh & Knight, 2011; Sun, Ong, & Burnette, 2012), caregiving of centenarians in Eastern and Western cultures has been covered to a lesser degree.

Caregiving Context: Cross-national Comparison

This study focused on the comparison of predictors associated with caregiver burden for centenarians between two countries: Japan and the U.S. The wider societal context plays an important role in influencing aging (Jopp, Boerner, Ribeiro & Rott, 2016). Laws and regulations in each country reflect cultural attitudes and traditions, which then influenced individual personal values and interpersonal relationships (Fung, 2013; Jopp et al., 2016). Furthermore, education, pension systems, and access to healthcare resources which support aging populations, are also influenced by cultural values and norms in each country. Therefore, relationships between care recipients and caregivers may vary depending on cultural values and societal context.

The values and belief systems in Eastern and Western cultures have been compared in many studies. For example, Lai (2010) examined the effects of filial piety on caregiver burden among Chinese Canadian family caregivers. Results suggested that stress was associated with a reduced negative effect on caregiver burden due to filial piety. This finding stressed the importance of the role of culture, especially in the appraisal of caregiver burden (Lai, 2010).

Purpose of Study

Given the theoretical frameworks and prior research, we addressed several questions based on previous studies. The first question is whether differences exist in caregiver burden for centenarians in Japan and the United States, which represent Eastern and Western cultures, respectively. Second, as people grow older, they commonly experience a decline in functional capacity; for example, Pinquart and Sörensen (2003) suggested that a care recipient’s physical and mental capacities showed stronger associations with caregiver outcomes than did other stressors. In addition, they asserted that an agreeable care recipient may express gratitude, provide emotional support and have sympathy for his or her caregiver (Pinquart & Sörensen, 2003), which further emphasized individual characteristics may contribute to the caregiving context. In consideration of previous research studies, our second research question focused on comparisons of predictive patterns in centenarian’s characteristics (functional capacity and personality), with caregiver burden. Finally, we assessed any moderation effect of country, in the relationship among functional capacity, personality, and caregiver burden, in order to explore societal and/or cultural impact on centenarians and their families.

Methods

Participants

The current study included near-centenarians and centenarians and their caregivers from two studies: Phase 3 of the Georgia Centenarian Study (GCS) (Poon et al., 2007) and the Tokyo Centenarian Study (TCS) (Hirose et al., 2004; Homma, Ishida, Hirose, & Nakamura, 1994). As shown in our previous work, the GCS, a population-based study, collected resources and adaptation from near-centenarians and centenarians and their proxies during four sequential sessions. The current study included 234 near-centenarians and centenarians and their proxy data from the GCS. The TCS is a comprehensive study of human aging at the final stage and longevity genes, in Japan. This study included 304 TCS near-centenarians and centenarians and their proxies who lived in the Tokyo metropolitan area. Participants responded to a mail-based survey and a subsequent visit survey (Gondo et al., 2006). The two studies include near-centenarians and centenarians, but the term centenarians is used for convenience purposes.

Proxy data for both studies were used as caregiver’s information in this study. The use of proxy-informant data may bring into a question the reliability due to potential inaccuracy. A number of studies, however, have shown that information from proxy informants is a reliable source for certain domains, such as activities of daily living, medical history, and instrumental activities of daily living (IADLs; Loewenstein et al., 2001; Martin, MacDonald, Margrett, Siegler, & Poon, 2013; Watkins, Guariglia, Kaye, & Janowsky, 2001; Weinberger et al., 1992). Furthermore, a significant relationship exists between self- and physician’s reports, and self and proxies’ reports, when oldest-old adults were involved in the study (Bassett, Magaziner, & Hebel, 1990).

When compared to self-ratings, a study that asked both, individuals with early-stage Alzheimer’s disease, and their informants, to fill out the NEO inventory, informant ratings were not only more sensitive to group differences, they better predicted early-onset dementia (Duchek, Balota, Storandt, & Larsen, 2007). Further, caregiver stress was determined by the perception of personality changes (Oddy, Humphrey, & Uttley, 1978). Therefore, the current study used information provided by proxies in the analyses. The reporting sources for each measurement are described in the Measures section. Table 1 shows the comparison of demographic characteristics among centenarians. The Japanese centenarians were slightly older than the American centenarians (101.48 years old vs. 100.23 years old, respectively). The proportion of men to women was higher among the Japanese centenarians, than the American centenarians (21.4% for TCS vs. 17.5% for GCS). Nearly 44% of the Japanese centenarians lived in their own homes, whereas 55% of American centenarians lived in their homes. The majority of caregivers were children; however, a higher proportion of children cared for Japanese centenarians than for American participants (i.e., 62.4% for GCS vs. 84.1% for TCS).

Table 1.

Centenarians’ Demographic Characteristics of Two Countries

Demographic Characteristics United States (n = 234) Japan (n = 304)
n % n %
Mean Age (sd)*** 100.23 (2.02) 101.48 (1.79)
Gender
 Female 193 82.5 239 78.6
 Male 41 17.5 65 21.4
Type of Residence*
 Living in Their House 103 44.2 167 54.9
 Nursing Facilities 130 55.8 137 45.1
Relationship With Caregiver***
 Children 143 62.4 190 84.1
 Family Members 69 30.1 20 8.8
 Others 17 7.4 16 7.1
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*

p < .05.

**

p < .01.

***

p < .001.

Note. Summary of numbers might not be same as study samples because of missing values.

Measures

Centenarian’s demographic characteristics.

Age, gender, caregiver relationship to centenarians, and living status, were included as demographic characteristics. Age was treated as a continuous variable for both sets of data. Gender was considered as a dichotomous variable (male = 0; female = 1). Two dummy variables (children vs. others; family vs. others) were created to include the caregiver’s relationship to the centenarian care recipient. Living status was coded as a dichotomous variable (1 = living together with centenarians; 0 = centenarian’s living in a nursing facility).

Centenarian’s functional capacity.

Functional capacity among older adults is directly related to caregiver burden (Savundranayagam, Montgomery, & Kosloski, 2011). This study included four types of functional capacity among centenarians: physical functioning, cognitive functioning, total number of major diseases, and vision and hearing problems. Physical functioning was measured with six items for activities of daily living (ADL) (Fillenbaum, 1988): eating, getting in and out of bed, dressing, bathing, and moving to the bathroom. Getting in and out of bed was excluded after testing the measurement invariance across countries. All five items were scaled so that 2 = without help (e.g., can walk, etc.); 1 = with some help (e.g., can get in and out of bed, but need some help from person or aid of some device); or 0 = totally unable to do the task (e.g., dependent on someone else to lift you). Cronbach’s alpha coefficients were .71 for the GCS and .89 for the TCS. A higher score in physical functioning indicated higher levels of the capacity for self-care. Cognitive functioning was assessed with a Mini-Mental Status Examination (MMSE) (Folstein, Folstein, & McHugh, 1975), a commonly used tool to evaluate cognitive impairment. A higher score on the MMSE indicated better cognitive status. Internal consistency estimate were .76 for the GCS and .88 for the TCS for this study. The summary of major diseases included nine common past and present health conditions and diagnoses (e.g., stroke, myocardial infarction, diabetes mellitus, and cancer) in both studies. Responses were scaled 0 (no) and 1 (yes). The total number of major diseases was indicated by reports from centenarians, proxies, medical charts, or care facility professionals, in both studies. The number of diseases was counted (ranging from 0 to 9), and higher scores indicated more health problems. Vision and hearing problems (0 = no, 1 = yes) were included because sensory impairments may hamper communication with caregivers and cause additional burden. Proxy reports were used to assess the centenarian’s personality and functional capacity, except for cognitive functioning and number of diseases, for both groups.

Centenarian’s personality.

Personality was measured with the Neo Five-Factor Inventory (Neo-FFI) (Costa & McCrae, 1992) in both studies. In the GCS, the Neo Personality Inventory (Neo PI-R) was used to examine the centenarian’s personalities; in the TCS, the Neo-FFI was used. The Neo PI-R consisted of 240 items with five personality traits and six specific facets. In order to compare the two studies directly, we reduced the number of items in the Neo PI-R in the GCS, to achieve comparability with items from the Neo-FFI used in the TCS. The Neo-FFI included five factors: extraversion, neuroticism, agreeableness, openness, and conscientiousness. Each of the five factors was composed of 12 questions, and each question was accompanied by a 3-point scale, ranging from −1 (disagree) to 0 (in between) to 1 (agree). A higher score indicated higher levels of the personality traits. Although each factor includes 12 questions, multi-group confirmatory factor analysis was used to test the invariance of the five factors of personality across countries (Δχ2 = 2.27, Δdf = 5, p < .05 for extraversion; Δχ2 = 3.10, Δdf = 8, p < .05 for neuroticism; Δχ2 = 11.44, Δdf = 7, p < .05 for openness; Δχ2 = 33.32, Δdf = 7, p < .05 for agreeableness; Δχ2 = 11.20, Δdf = 5, p < .05 for conscientiousness). A couple of questions per each personality factor were excluded, in order to select equivalent questions across countries. This resulted in a reduction in the number of questions (7 questions for extraversion, 9 questions for neuroticism, 6 questions for openness, 8 questions for agreeableness, and 8 questions for conscientiousness). Reliabilities of the GCS and the TCS for each domain with selected questions were .66/.76, .78/.64, .72/.67, .71/.82, .81/.77 for extraversion, neuroticism, openness, agreeableness, conscientiousness, respectively. Proxy reports were used to assess the centenarian’s personalities for both groups.

Caregiver’s caregiving burden.

Zarit’s Burden Interview (ZBI, 22 items) (Zarit, Reever, & Bach-Peterson, 1980) were used to assess physical and emotional strain on caregiving experiences, on a 5-point scale ranging from 0 (never) to 4 (nearly always). Scores ranged from 0 to 88, with higher total scores indicating greater levels of caregiver burden. Internal consistencies of caregiver burden scales were α = .90 for the GCS caregivers and α = .93 for the TCS caregivers.

Analyses

Two analyses were conducted. First, descriptive analyses (i.e., means, standard deviations, chi-square tests, analyses of variance) were performed to compare variables and evaluate the bivariate relationship in target variables in two centenarian groups. Second, block-wise multiple regression models were computed to identify significant predictors for caregiver burden in the two countries. Five models were compared. In the first model, the centenarian’s demographic variables (e.g., age, gender, caregiver relationship to care recipient, and residential status) were included (Model 1). In the second model, the centenarian’s physical functioning, cognitive functioning, number of diseases, and vision and hearing problems were included, after controlling for demographic variables (Model 2). The centenarian’s Big Five personality factors were included in the third model (Model 3).

After creating 25 interaction terms between personality factors and functional capacity, we examined whether care recipients’ functional capacity, personality, and their interactions predicted caregiver burden in each country (Model 4). Models 1 to 4 were performed separately in the two studies. Lastly, another set of regression analyses were conducted to explore differential predictive patterns in both countries, by testing three-way interaction effects (e.g., country*ADL*neuroticism, country*ADL, country*neuroticism, neuroticism*ADL) on caregiver burden (Model 5). Pairwise deletion dealt with missing data. To examine the two-way interactions and three-way interactions, all continuous predictor variables were mean-centered to examine the difference in the influence of centenarian’s personality and functioning on caregiver burden. Furthermore, the PROCESS procedure was conducted to test significance of slopes at different levels of personality (Hayes, 2013).

Results

Comparisons in Caregiver Burden, Functional Status, and Personality

The first goal of this study was to examine country differences in mean levels of caregiver burden, and its functional and personality predictors, as shown in Table 2. Significant differences between the two cultures were found in caregiver burden, F (1, 436) = 30.97, p < .001; cognitive functioning, F (1, 502) = 36.65, p < .001; number of diseases, F (1, 476) = 19.92, p < .001; neuroticism, F (1, 495) = 9.46, p < .01; extraversion, F (1, 496) = 11.63, p < .05; conscientiousness, F (1, 495) = 3.98, p < .05; and hearing problem, x2 (1) = 10.82, p < .01. In the Japanese study, higher levels of caregiver burden, lower levels of cognitive status, a greater number of diseases, higher levels of neuroticism, extraversion, and conscientiousness, and more hearing problems were observed,than in the American study.

Table 2.

Comparisons in Study Variables between Two Countries

United States (n = 234a) Japan (n = 304a) F/x2
Caregiving Burden (0 to 88) 18.26 (±12.91) 26.37 (±17.31) 30.97***
ADL (1 to 10) 5.99 (±2.40) 5.53 (±3.18) 3.31
MMSE (0 to 30) 17.12 (±8.62) 12.45 (±8.64) 36.65***
Number of Disease (0 to 6) 1.20 (±.95) 1.66 (±1.14) 19.92***
Neuroticism (−9 to 8) −3.96 (±4.12) −2.91 (±3.47) 9.46**
Extraversion (−7 to 7) 2.84 (±2.95) 1.87 (±3.31) 11.63**
Openness (−6 to 6) −.33 (±2.91) .05 (±2.85) 2.18
Agreeableness (−8 to 8) 4.06 (±3.09) 3.67 (±3.73) 1.62
Conscientiousness (−7 to 8) 4.43 (±3.43) 3.82 (±3.40) 3.98*
Vision problem 86 (54.1%) b 192 (63.2%) b 3.58
Hearing problem 91 (57.6%) b 221 (72.7%) b 10.82**
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*

p < .05.

**

p < .01.

***

p < .001.

a

. Sample size varies depending on the number of missing values.

b

. Presents frequencies and %.

Predictors Associated With Caregiver Burden in the United States and Japan

Block-wise multiple regression analyses showed significant correlates of caregiver burden in the two countries (Tables 3 & 4). There was no multicollinearity in the regression analyses. In terms of demographic characteristics, the relationship of caregiver was significantly associated with caregiver burden for Americans (β = .44, p < .01 for children; β = .33, p < .05 for family), whereas being female (β = .16, p < .05) and being children caregivers (β = .23, p < .05) were significant in Japanese caregivers’ burden. As far as functional capacity, both groups of participants showed different significant predictors. For GCS caregivers, cognitive functioning (β = −.23, p < .05) and number of diseases (β = .18, p < .05) were significant predictors of caregiver burden, whereas only physical functioning (β = −.22, p < .05) was significant in the TCS caregiver burden, after controlling for demographic characteristics. Personality factors were significantly associated with caregiver burden in both groups. For GCS caregivers, neuroticism (β = .20, p < .05), agreeableness (β = −.17, p < .05), and conscientiousness (β = −.18, p < .05) were significant; whereas, openness (β = −.20, p < .01) and agreeableness (β = −.33, p < .001) were significant for the TCS caregivers.

Table 3.

Predictors of Caregiving Burden in the U.S. (n = 234)

Variables Model 1 Model 2 Model 3 Model 4
β R2 FΔ β R2 FΔ β R2 FΔ β R2 FΔ
Demographics .08 2.77* .17 3.35** .39 10.83***
 Centenarian’s age .02 −.05 −.03
 Centenarian’s sex (male=0; female=1) .01 .04 .01
 Children caregiver (=1 vs. others=0) .44** .35* .37**
 Family caregiver (=1 vs. others=0) .33* .26 .23
 Living together (=1 vs. nursing facility=0) .16 .20* .18*
Centenarian’s functional capacity
 Physical functioning −.09 −.06
 Cognitive functioning −.23* .16
 Number of disease .18* .21**
 Hearing problem .32 .46**
 Visual problem −.11 −.14
Centenarian’s personality
 Neuroticism .20*
 Extraversion −.13
 Openness .07
 Agreeableness −.17*
 Conscientiousness −.18*
Interaction terms
 Physical functioning*Neuroticism .14* .38 4.15*
 Physical functioning*Extraversion −.16* .38 5.35*
 Cognitive functioning*Extraversion −.17* .39 5.51*
 Number of disease*Openness −.15* .38 4.04*
 Visual problem*Agreeableness −.33** .40 7.74**
 Hearing problem*Agreeableness −.26* .37 4.01*
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*

p < .05.

**

p < .01.

***

p < .001.

Table 4.

Predictors of Caregiving Burden in Japan (n = 304)

Variables Model 1 Model 2 Model 3
β R2 FΔ β R2 FΔ β R2 FΔ
Demographics .08 3.39** .13 2.04 .30 8.86***
 Centenarian’s age −.06 −.11 −.09
 Centenarian’s sex (male=0; female=1) .16* .12 .09
 Children caregiver (=1 vs. others=0) .23** .24* .26**
 Family caregiver (=1 vs. others=0) .05 .08 −.08
 Living together (=1 vs. nursing facility=0) −.10 −.05 −.03
Centenarian’s functional capacity
 Physical functioning −.22* −.29**
 Cognitive functioning .05 .10
 Number of disease .02 −.01
 Hearing problem .10 .06
 Visual problem .03 .00
Centenarian’s personality
 Neuroticism .05
 Extraversion .04
 Openness −.20**
 Agreeableness −.33***
 Conscientiousness −.01
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*

p < .05.

**

p < .01.

***

p < .001.

Furthermore, Model 4s, including two-way interaction effects on caregiver burden, were examined by country. Six interaction effects were significant on caregiver burden among GCS caregivers only: physical functioning and neuroticism (β = .14, p < .05), physical functioning and extraversion (β = −.16, p < .05), cognitive functioning and extraversion (β = −.17, p < .05), number of diseases and openness (β = −.15, p < .05), vision problem and agreeableness (β = −.33, p < .01), and hearing problem and agreeableness (β = −.26, p < .05). No significant two-way interaction effects on caregiver burden was found among TCS caregivers.

With regard to country, Models 5, including three-way interactions for functioning capacity*personality*country (with constituent two-way interactions and main effects) on caregiver burden, were performed to examine whether associations between functional capacity and personality, varied by country. No significant three-way interaction effects on caregiver burden was found.

Interaction Effect of Personality on Caregiver Burden

In order to further characterize the nature of the six, two-way interaction effects, the PROCESS model was applied to perform slope tests (Hayes & Matthes, 2009; Hayes, 2013). Slope tests found two significant interactions: number of diseases and openness, and vision problems and agreeableness. In other words, the association between caregiver burden and the number of diseases, was stronger when GCS caregivers reported that the centenarian’s openness was low. When GCS caregivers perceived low levels of openness and fewer diseases in the centenarians, GCS caregivers reported lower levels of caregiver burden. When GCS caregivers reported low levels of openness and a greater number of diseases in the centenarians, GCS caregivers reported higher levels of caregiver burden. When caregivers scored higher on the centenarian’s openness, the number of diseases seemed to have little effect; these caregivers reported similar levels of caregiver burden (Figure 1).

Figure 1.

Figure 1.

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Caregiver burden and interaction between centenarian’s openness and disease among GCS participants

The relationship between caregiver burden and vision problems was also stronger when GCS caregivers reported that the centenarian’s level of agreeableness was high. When GCS caregivers perceived higher levels of agreeableness in the centenarians with vision problems, these caregivers reported lower levels of caregiver burden, when compared to caregivers who took care of centenarians without vision problems. When caregivers scored lower on the centenarian’s agreeableness, vision problems seemed to have little effect. In addition, the level of caregiver burden was not significantly different regardless of the centenarian’s vision problems (Figure 2).

Figure 2.

Figure 2.

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Caregiver burden and interaction between centenarian’s agreeableness and vision problem among GCS participants

Discussion

As the number of oldest-old adults has increased, informal or family care has become more and more important all over the world. According to the sociocultural stress and coping model (Aranda & Knight, 1997; Knight & Sayegh, 2010), societal context and cultural values play a critical role in the context of caregiving, and may better explain cross-cultural, and/or cross-national differences, in resources and coping strategies (e.g., Löckenhoff et al., 2016; Sayegh & Knight, 2011). Moreover, the multiaxial model of coping accounts for that factors such as individual interpretation, family norms, cultural biases coping strategy could determine coping strategies in caregiving context (Kuo, 2011). With the burden that is placed on caregivers receiving more attention, this study aimed to address caregiver burden for those caregivers of centenarians, and the cross-national differences in the caregiving context, between two countries: Japan and the United States. Results indicated that Japanese caregivers reported higher levels of caregiver burden, than their American counterparts. Our findings further suggested that the centenarian’s differing functional capacities and personality traits predicted levels of caregiver burden in both groups. In addition, the influence of the centenarian’s level of agreeableness on caregiver burden may be important regardless of cultural values in the two countries.

To our knowledge, this is the first research study which examined a cross-cultural, and/or cross-national comparison, in the context of caregiving with centenarians. Findings of the current study are consistent with other prior studies on younger care recipients (than centenarians) in that caregiver’s burden was significantly associated with care recipient’s functional capacities and personality traits. The cross-national comparison further indicated longevity not only influenced individuals, but also their family and society. Results also suggested the importance and need for caregiving, along with unique ways to provide informal and formal care for centenarians in at the societal and cultural levels. The growth in the number of the oldest-old presents a challenge in finding available informal caregivers from younger generations, due to decreased fertility rates and increased job mobility (Uhlenberg & Cheuk, 2008). As the need to maintain sufficient informal caregiving and further enhance societal support and services (Takagi, Davey, & Wagner, 2013), it is important to pay attention to the future of care for centenarians. Caregivers of centenarians may be the secret to successful care, such as reducing their burden for caregiving, which leads to better long-lasting family care. The study of caregiving may serve to provide a successful care mastery model for informal or family caregivers of centenarians, including those individuals with chronic diseases, such as Alzheimer’s disease.

The major finding of this study was that caregivers showed different levels of caregiver burden from two countries. In past research, caregiver burden was shown to be lower for American caregivers and at moderate levels, for Japanese caregivers (Zarit et al., 1980). In this study, Japanese caregivers reported higher levels of burden than American caregivers. This may be explained because higher levels of cognitive impairment, a greater number of diseases, and more centenarians with hearing problems were observed in the Japanese study, compared to the American study. However, multivariate regression analyses showed that those factors were not significantly associated with caregiver burden.

Filial obligation for family caregiving may be another possible explanation for higher levels of caregiver burden among Japanese caregivers. In Asian culture, filial piety has played a dominant role in the decision to live with parents in old age, and provide care (Pharr, Francis, Terry, & Clark, 2014). In contrast, providing care to parents is more of a personal choice among European American caregivers (Pharr et al., 2014). Pharr and colleagues (2014) concluded that caregiving was not embedded in life experiences nor is it expected, among European American caregivers; whereas, caregiving was deeply rooted in the cultural norm and performed without question, among Asian caregivers. Therefore, it may be concluded that physical and emotional strain may be more pronounced among Asian caregivers because caregiving was not a choice.

The most noteworthy finding of this study was the similarities and differences in predictive patterns of caregiver burden, which indicated that culture and/or country plays a significant role in the context of caregiving. The theory of construing the self-supported this result (Markus & Kitayama, 1991). It was theorized that appraisal of aging, caregiving, and perception of personality traits may be influenced by culture. Personal traits and preferences, as well as, individual values as independent and separate from others, are important in the West. I n contrast, social roles and norms lead to the expectation of being interdependent with others and emphasizes relationships with others, in the East (Markus & Kitayama, 1991, 2010). With this in mind, centenarians higher in openness was significantly associated with caregiver burden in Japan, whereas centenarians higher in conscientiousness was significantly associated with caregiver burden in the U.S. If centenarians in the U.S. tended to be conscientious, meaning that they tried to be self-controlled, caregivers might have difficulty taking care of them, thereby raising the level of burden. There is an old saying in Japan: “Once you get old, you should follow younger generations.” Japanese centenarians with higher levels of openness, meaning that they would follow a younger caregiver’s opinions, instead of going with their own, may have led to lower levels of caregiver burden among Japanese caregivers. Denissen, van Aken, and Dubas (2009) suggested that the personalities of parents and their adolescent children predicted the quality of their relationship; however, evidence incorporating oldest-old parents and their adult children, remains sparse. Future studies should focus on caregiving relations in very old parents and their adult children.

This study found that the care recipient’s personality traits were significantly associated with caregiver burden. In accordance with prior research, our regression models showed that agreeableness was a common protective predictor for caregiver burden in both countries. Riffin, Löckenhoff, Pillemer, Friedman, and Costa (2013) addressed the importance of individual and interpersonal aspects of caregiving experiences, and showed that agreeableness of care recipient was closely linked to the caregiver’s physical health. White, Hendrick, and Hendrick (2004) also found that personality traits were most closely related to interpersonal processes and relationship satisfaction. Whereas these studies did not include a centenarian’s personality, the findings of the current study reinforces the importance of the care recipient’s personality in the context of caregiving, and the quality of life among caregivers.

Lastly, functional capacity among centenarians showed different predictive patterns of caregiver burden between the two countries, when the interaction effect of personality was examined. The relationship between caregiver burden and functional capacity (i.e., number of diseases and vision problems) differed from the levels of the centenarian’s personality (i.e., openness and agreeableness, respectively) in American caregivers, whereas no interaction effects of personality were significant in the relationship between functional capacity and caregiver burden, in the Japanese caregivers. This might be explained by cultural differences in coping style and social support. Appraisal of caregiver burden or receiving social support might be an explanation in a racial or ethnic group dominated by familism (Knight, & Sayegh, 2010; Knight et al., 2002), rather than the care recipient’s characteristics. In addition, there is a greater amount of medical and social care support which may serve to buffer caregiver burden in Japan. A close examination of cultural differences in coping styles, social support, and societal conditions of providing care should be the next step in future studies.

Limitations and Conclusion

This study has yielded several important findings; nevertheless, potential limitations should also be noted. First, although we used two centenarian studies in two different countries, the samples of this study were from only one geographic area of each country (i.e., Tokyo in Japan and Georgia in the U.S.). Thus, the results of this study might not be generalized to other Eastern and Western countries.

Second, for the Georgia Centenarian Study, we identified caregivers as proxy informants; for example, we first identified spouses, then adult children, then other family members, and community members. Some caregivers did not see themselves as caregivers, so their level of caregiver burden might have been lower than those who saw themselves as sole caregivers. In Japan, caregivers were mostly children: eldest sons and daughters-in-law were culturally expected to care for their older parents. Caregiver burden might differ according to more specific relations to the centenarians. This study did not include caregiver characteristics such as the caregiver’s health, number of caregiving hours and duration, or psychological characteristics (e.g., perceived social support) that may be associated with caregiver burden. This may explain differences in the level of caregiver burden in the two countries.

Third, we used centenarian’s personality as reported by the caregivers. Numerous researchers have demonstrated that proxy informants are reliable and suitable for self-reports (MacDonald, Martin, Margrett, & Poon, 2010). However, we should consider that a disagreement about personality may result in differences from proxy to self-reports for these centenarians.

Fourth, we examined national differences in mean levels of the major variables and used equivalent factor loadings across studies. Unfortunately, caregiver burden did not show measurement invariance between the two countries and used 22 original items. Future study should focus on measurement invariance for caregiver burden among centenarian caregivers, between two countries.

Fifth, other possible factors that might have affected national differences were not considered, such as economic resources or the education of the care recipients. That information was difficult to collect because centenarians may rely on their family, community, or other societal support, such as Social Security benefits, Medicare, and Medicaid, for financial resources. Therefore, centenarian care recipients may pay little attention to their day-to-day financial resources. Moreover, education was difficult to compare due to the different educational systems in the two countries. A formal educational system had not been established until after WWII in Japan, whereas compulsory schooling in the U.S. began in the mid-18th century.

Lastly, although this study examined the cross-cultural, and/or cross-national comparison, in the context of caregiving, differences in societal conditions of providing care between the U.S. and Japan were not addressed. For example, the Japanese government initiated mandatory public long-term care insurance in 2000 (Kaye, Harrington, & LaPlante, 2010; Tamiya et al., 2011), whereas long-term care insurance in the U.S. is an individual or family’s choice. Societal support for individuals and family caregivers would impact caregiving context.

In conclusion, we found similarities in the context of caregiving and unique differences in the relationship between a centenarian care recipient’s personality and caregiver burden in two different countries: Japan and the U.S. The impact of longevity may not only vary for individuals, but also for family and society. Future researchers should consider the role of culture in the individual, the family, and society, with a variety of measures, to better provide an underpinning for policies involving centenarians and their families.

Acknowledgments

This research was funded by the program for Promoting the Enhancement of Research Universities from Osaka University, Osaka, Japan.

The Georgia Centenarian Study (Leonard W. Poon, PI) was funded by 1P01AG17553 from the National Institute on Aging, a collaboration among the University of Georgia, Tulane University Health Sciences Center, Boston University, University of Kentucky, Emory University, Duke University, Wayne State University, Iowa State University, Temple University, and University of Michigan. Additional authors include S. M. Jazwinski, R. C. Green, M. MacDonald, M. Gearing, W. R. Markesbery (deceased), J. L. Woodard, M. A. Johnson, J. S. Tenover, I. C. Siegler, W. L. Rodgers, D. B. Hausman, C. Rott, A. Davey, and J. Arnold. Authors acknowledge the valuable recruitment and data acquisition effort by M. Burgess, K. Grier, E. Jackson, E. McCarthy, K. Shaw, L. Strong, and S. Reynolds, data acquisition team manager; S. Anderson, E. Cassidy, M. Janke, and J. Savla, data management; M. Poon, project fiscal management.

The Tokyo Centenarian Study was supported in part by a grant from the Japanese Ministry of Health and Welfare for the Scientific Research Project on Longevity, a grant for studying the multidisciplinary approach to centenarians and its international comparison (Principal Investigator, Nobuyoshi Hirose); a grant from the Japanese Ministry of Education, Science, and Culture (No.15730346); and aid for research from the Keio Health Consulting Center. We also would like to thank Dr. Hiroki Inagaki for preprocessing cognitive assessment data for the Tokyo Centenarian Study.

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