Depressive Symptoms Among Caregivers of Older Adults With Both Diabetes and Functional Limitations and Moderation by Caregiver Expressive Social Support

Abstract

Purpose

The purpose of the study was to explore how caring for older adults with both diabetes and functional limitations impacts caregiver depressive symptoms and whether this impact is moderated by caregivers’ expressive social support and psychological resilience.

Method

Cross-sectional data of 278 dyads, each comprising an older adult with functional limitations and his/her primary family caregiver were analyzed. Older adult diabetes status (yes/no) was based on ever-diagnosis of diabetes. Caregiver depressive symptoms, expressive social support, and psychological resilience were measured using standard scales. Multivariable linear regression was used to assess the association of interest and its moderation by caregiver expressive social support and psychological resilience.

Results

Caregivers of older adults with both diabetes and functional limitations had a higher depressive symptoms score compared to caregivers of older adults with only functional limitations. This association was inversely moderated by caregiver expressive social support. As caregiver expressive social support increased, the difference in depressive symptoms between caregivers of older adults with diabetes and functional limitations and caregivers of older adults with only functional limitations reduced.

Conclusion

Family caregivers of older adults with functional limitations and diabetes have a higher depressive symptoms score. However, enhancing caregiver expressive social support could mitigate this risk. Service providers should prioritize support for caregivers in such vulnerable situations and strive to enhance their expressive social support.

Family caregivers play an important role in long-term care provision for older adults.¹ It is estimated that in Singapore, the setting of this study, at least 6% to 8% of adults ages 18 to 59 years provide unpaid care to a family member.² Caregivers’ responsibilities include assisting care recipients with basic activities of daily living (ADLs), instrumental ADLs (IADLs), socioemotional needs, and use of health and social care services. Caregiving is not only physically but also psychologically demanding—caregivers have been found to have higher psychological distress than the general population and substantial depressive and anxiety symptoms,^3,4 which at times are comparable with their care recipients.⁵ Depression is a key adverse psychological consequence of caregiving,⁶ and the prevalence of depression among caregivers of older adults has been found to be higher compared to noncaregivers.^1,7,8 Based on Pearlin et al’s⁹ stress process model, studies have determined that poor functional and health status of care recipients are “stressors” associated with caregiver depression.^10,11 Family caregivers of older adults with functional limitations, such as ADL or IADL limitations, have been reported to experience higher level of depression than noncaregivers.¹² A study in Netherlands showed that care recipients’ functional limitations and multimorbidity were associated with mental health problems among spousal caregivers,¹³ and another study in the United States found that care recipients’ functional status predicted depressive symptoms among family caregivers.¹⁴ Similarly, previous research has shown a high level of depressive symptoms and stress among caregivers providing intensive care to older adults with chronic diseases.^6,15,16 Caregivers of older adults with chronic diseases may need to provide physically demanding care and often coordinate routines and schedules with other family and formal caregivers and health and social care services throughout the course of the care recipient’s illness.^17,18 One such common yet complex chronic disease is diabetes mellitus (hereafter, “diabetes”). In previous literature, family caregivers of patients with more severe diabetes have been found to be an increased risk of depression, poorer quality of life, higher caregiving strain, and higher level of burnout compared to either noncaregivers or caregivers of care recipients with fewer complications of diabetes.^19
-22

These separate streams of literature highlight the negative psychological consequences, in particular, depression, for caregivers when they care for older adults with functional limitations and for older adults with diabetes. However, it is not known if the presence of both diabetes and functional limitations in older adults, versus only functional limitations, is associated with greater adverse psychological consequences among their family caregivers. This study compares the extent of depressive symptoms between caregivers of older adults with both diabetes and functional limitations and caregivers of older adults with only functional limitations. Furthermore, this is done among caregivers of community-dwelling older adults ages 75 years or older, thereby expanding the literature beyond clinical settings. This is important because previous studies have mostly studied caregivers in the context of patients with diabetes who have undergone surgery or hospitalization for their diabetes complications.^19
-22 There is limited literature on the family caregiving experience for older adults with diabetes outside the context of hospitalization or health care services.

Additionally, it has been argued in previous research that although care recipient’s health conditions and functional limitations are linked with caregiver depressive symptoms, availability of emotional support for caregivers and caregiver self-esteem can reduce negative experiences of caregiving and subsequently, caregiver depressive symptoms.²³ Expressive social support, that is, the extent to which the caregiver has someone from his/her family and friends to trust and confide in,²⁴ is often regarded as a protective factor against caregivers’ depression and anxiety.^25,26 There is substantial literature on social support and depression in caregivers—greater social support can relieve caregiver burden, which in turn lowers caregiver depressive symptoms.^27
-32 Strong expressive social support can help caregivers cope with difficult times by helping share sentiments and feelings, reducing stress through “reassurances” and through the perception that support is available from others when required.^33,34 The extent to which caregivers experience psychological distress, specifically, depressive symptoms, can therefore vary by the extent of expressive social support that they have. This moderating role of social support on the impact of caregiving stressors on caregivers has been documented before.^29,34,35 In a study of caregivers of persons with dementia where social support was measured through multiple distinct constructs, the receipt of social support, caregivers’ satisfaction with the support they received, and social networks separately buffered the impact of greater caregiving intensity on caregiver burden.³⁵ Another study of caregivers of patients with Alzheimer’s disease reported that the relationship between patient factors, that is, their cognitive function and depression, and caregiver burden was buffered by social support (a composite measure of subjective and objective social support and social support utilization); however, the relationships between patient factors and caregiver anxiety or depression were not moderated by social support.²⁹ Expressive social support was also found to moderate the relationship between care-related work interruptions as a main stressor and caregiver depressive symptoms among caregivers of older adults with functional limitations.³⁴

Similarly, another protective factor or resource that may help caregivers cope with stressors is their psychological resilience, defined as “the ability to adapt positively to life conditions” that allows people to recover in face of difficulties and “bounce back.”³⁶ Higher psychological resilience has been reported to be associated with lower burden and depressive symptoms among caregivers.³⁷ Caregivers with higher resilience can adapt and cope with caregiving difficulties and therefore can be protected against psychological distress from caregiving burden.^38,39 A systematic review has summarized the strong inverse association between resilience level of caregivers and caregiving burden and emotional distress.³⁹ The moderating role of psychological resilience has been studied in the context of caregivers of persons with mental illness and with dementia: For example, it has been found to buffer the association between perceived stigma and psychological distress among caregivers of patients with schizophrenia⁴⁰ and between perceived role overload and sleep disturbances among caregivers of older persons with dementia.⁴¹ In addition, Teahan et al’s⁴² systematic review found that resilience is a necessary resource for caregivers of people with dementia with intensive caring activities and needs. Although resilience or carers’ capacity to adapt to adversity and psychological distress is highly influenced by context of care, resilience may be a potential buffer in the association between caregiving stressors and caregiver’s mental well-being in a general population of caregivers.

In addition to the empirical evidence cited so far, theoretically, the stress process model^9,43 suggests that differences in social support and coping among caregivers can explain the differences in or potentially buffer the impact of primary stressors (eg, care recipients’ functional limitations and health care needs) on caregiver outcomes (eg, depression). Thus, although the protective role of expressive social support and psychological resilience in the context of caregiver well-being has been well documented and supported by theory, their moderating role vis-à-vis caregiver outcomes remains underexplored. This study aims to assess whether these potentially modifiable caregiver factors buffer the impact of caring for older adults with both diabetes and functional limitations on caregiver depressive symptoms.

Thus, based on previous studies that demonstrate the negative psychological consequences among caregivers when they care for older adults with functional limitations and for older adults with diabetes, this study tests two hypotheses:

Hypothesis 1: The extent of depressive symptoms is higher among caregivers of older adults with both diabetes and functional limitations compared to caregivers of older adults with only functional limitations.

Hypothesis 2: Caregiver expressive social support and psychological resilience moderate the association of caring for older adults with both diabetes and functional limitations (compared to those with only functional limitations) with caregiver depressive symptoms.

Methodology

Data Source

This study analyzes data from the baseline survey of the Caregiving Transitions Among Family Caregivers of Elderly Singaporeans (TraCE) study, conducted in 2019-2020. The TraCE study is a longitudinal study aimed at understanding the health and social lives of caregivers of community-dwelling older adults in Singapore. It surveyed older care recipient/caregiver dyads up to 4 times: at baseline and up to 3 follow-ups at 6- to 12-month intervals. For identifying older care recipients, a total of 1895 adults ages 75 years or older, who had participated in 2 national surveys in Singapore, were administered a screener to assess their ADLs and IADLs status. Six ADLs (take a bath or shower, dress up, walk around the house, stand up from or sit down on a bed or chair, use the sitting toilet, eat) and 7 IADLs (take public transport to leave home; leave home to purchase necessary items or medication; take care of financial matters such as paying utilities; dust, clean-up, and other light housework; prepare own meals; take medication as prescribed; use the phone) were considered. Older adults who reported that they received human assistance for any of the considered ADLs or IADLs were classified as care recipients. For each older care recipient, a family member or friend who was most involved in at least 2 of following activities in context of the care recipient—(a) direct care, (b) care supervision, and (c) decision-making—was identified as his/her primary family caregiver. A total of 278 older care recipient/caregiver dyads were included in the baseline survey of the study. Further details of participant recruitment and conduct of the TraCE study are described elsewhere.^44,45

Measures

Independent variable: care recipient’s diabetes status

Care recipients (or their caregiver if care recipients could not respond themselves due to their health condition), all of whom had functional limitations, were asked if they had ever been diagnosed by a health care professional with diabetes. The response informed the variable care recipient with diabetes (yes/no).

Outcome: caregiver depressive symptoms

The 11-item Center for Epidemiologic Studies-Depression scale (CES-D),⁴⁶ which has been employed previously in Singapore to assess caregiver depressive symptoms,^47,48 was used. Each item (eg, “I felt that everything I did was an effort”; “I felt sad”) was asked in the context of the past week and had 3 response options: none/rarely (scored as 0), sometimes (scored as 1), and often (scored as 2). The total score, that is, the sum of the individual item scores, ranges from 0 to 22 (Cronbach’s α in analysis sample = 0.83), with a higher score indicating a higher number of symptoms associated with depression. The continuous variable was used as the outcome in the primary analysis. A dichotomous variable, clinically relevant depressive symptoms, indicated by a total score of 7 and above,⁴⁹ was used as the outcome measure in sensitivity analysis.

Moderator: caregiver expressive social support

Expressive social support among caregivers was measured using Pearlin et al’s⁴³ 8-item scale, which has been used in previous studies in Singapore.^50,51 Caregivers were asked to what extent they agreed or disagreed to 8 statements about help and support they got from their friends and relatives other than the care recipient. Each item (eg, “You have someone whom you feel you can trust”; “The people close to you let you know that they care about you”) was scored on a 4-point scale, assessing the extent of agreement, from strongly disagree (scored as 1) to strongly agree (scored as 4). Item scores were added for a continuous score ranging from 8 to 32 (Cronbach’s α in analysis sample = 0.76), with a higher score indicating greater expressive social support.

Moderator: caregiver psychological resilience

Psychological resilience among caregivers was assessed using the 2-item Connor and Davidson resilience scale (CD-RISC-2®),⁵² which, too, has been used to assess resilience among caregivers in Singapore.^53,54 Each item (“adapt to change”; “bounce back from adversity”), asked in the context of the past month, had 5 response options from not true at all (scored as 0) to true nearly all the time (scored as 4). The CD-RISC-2 score was calculated by adding the score of the 2 items, and it ranges from 0 to 8 (Spearman’s α in analysis sample = 0.59), with a higher score indicating greater psychological resilience.

Covariates: care recipient and caregiver characteristics

Care recipient and caregiver demographics and health conditions were included as covariates in the statistical analysis. Care recipient’s demographics included age, sex, ethnic group (Chinese/Malay/Indian/others), and educational attainment (no formal education/primary/secondary and above). Caregiver demographics included age, sex, educational attainment, housing type (1- to 3-room flat/public rental flat/4- to 5-room flat or above, condominium, or private flat/bungalow, semidetached, or terrace house), and perceived financial adequacy for monthly household expenses (more than adequate/adequate/occasionally adequate/usually inadequate).

The care recipient’s health conditions included any chronic conditions other than diabetes (yes/no), any ADL limitation (yes/no), and any IADL limitation (yes/no). Caregiver health conditions included any ADL or IADL limitation (yes/no), any chronic condition (yes/no), self-rated health (excellent/very good/good/fair/poor), and any physical function difficulty (assessed through Nagi’s⁵⁵ disability model; yes/no). Additional caregiver characteristics included as covariates were provision of care to others (ie, someone other than care recipient; yes/no), cohabitation with care recipient (yes/no), and relationship with care recipient (spouse/other).

Data Analysis

First, descriptive statistics were used to examine the outcome, moderators, and covariates, overall and stratified by care recipient’s diabetes status. Second, multivariable linear regression analyses were conducted to assess the association of care recipient’s diabetes status (yes/no) with caregiver depressive symptoms score, controlling for caregiver expressive social support, caregiver psychological resilience, and the various care recipient and caregiver characteristics listed as covariates previously. Third, interaction terms of care recipient’s diabetes status with caregiver expressive social support and with caregiver psychological resilience were added to the linear regression model to test for their role as moderators of the association. Sensitivity analysis was conducted by using binary logistic regression analyses, first without and then with the interaction terms, to assess the association of care recipient’s diabetes status with caregiver clinically relevant depressive symptoms and its moderation. All analyses were conducted using Stata 15.

Ethical Approval and Informed Consent

The TraCE study was approved by the Institutional Review Board (IRB) of the National University of Singapore (IRB Reference No. LS-18–387C). Written informed consent was taken either from caregivers and care recipients both or from only the caregiver if the care recipient was unable to respond due to health reasons. In the latter situation, the caregiver responded as a proxy for questions addressed to the care recipient.

Result

Table 1 shows descriptive analyses of the 278 care recipient/caregiver dyads. About 34% of the care recipients had diabetes. The mean depressive symptoms score (CES-D) of caregivers of care recipients with diabetes was 5.0 (SD 4.1) and of caregivers of care recipients without diabetes was 4.3 (SD 4.1). Although 29.8% of caregivers of care recipients with diabetes had clinically relevant depressive symptoms, the corresponding proportion was lower at 25.0% among caregivers of care recipients without diabetes (P = .39). The mean scores of psychological resilience (CD-RISC-2®) and expressive social support (Pearlin et al’s⁴³ 8-item scale) were 24.1 (SD 3.2) and 5.8 (SD 1.6), respectively, among caregivers of care recipients with diabetes, and they were 23.7 (SD 3.3) and 5.4 (SD 1.6), respectively, among caregivers of care recipients without diabetes. However, in this bivariate analysis, caregivers of care recipients with and without diabetes differed only in terms of psychological resilience (P = .046). In terms of care recipient characteristics, only age was significantly different between those with diabetes (mean age: 84.4; SD 4.8) and without diabetes (mean age: 86.0; SD 5.5), the former being slightly younger (P = .016). In the context of caregiver characteristics, none of the considered covariates differed between caregivers of care recipients with diabetes and caregivers of care recipients without diabetes.

Table 1

Distribution of Caregiver Depressive Symptoms, Caregiver Psychological Resilience, Caregiver Social Support, and Covariates (Care Recipient and Caregiver Characteristics) by Care Recipient Diabetes Status

Variable		Care recipient with diabetes^a n (%) or mean (SD)
Variable	Total(N = 278)	Yes(n = 94; 33.8%)	No(n = 184; 66.2%)	P value
Outcome
Caregiver depressive symptoms, continuous	4.6 (4.1)	5.0 (4.1)	4.3 (4.1)	.19
Caregiver clinically relevant depressive symptoms				.39
Yes (score ≥7)	74 (26.6%)	28 (29.8%)	46 (25.0%)
No (score <7)	204 (73.4%)	66 (70.2%)	138 (75.0%)
Moderators
Caregiver expressive social support^b	23.8 (3.3)	24.1 (3.2)	23.7 (3.3)	.25
Caregiver psychological resilience^b	5.6 (1.6)	5.8 (1.6)	5.4 (1.6)	.046
Care recipient characteristics
Age (y)	85.4 (5.3)	84.4 (4.8)	86.0 (5.5)	.016
Sex				.11
Male	93 (33.5%)	37 (39.4%)	56 (30.3%)
Female	185 (66.5%)	57 (60.6%)	128 (69.7%)
Ethnic group				.39
Chinese	189 (68.0%)	59 (62.8%)	130 (70.7%)
Malay	52 (18.7%)	19 (20.2%)	33 (17.9%)
Indian	34 (12.2%)	14 (14.9%)	20 (10.9%)
Others	3 (1.1%)	2 (2.1%)	1 (0.5%)
Highest education				.15
No formal education	154 (55.4%)	55 (58.5%)	99 (53.8%)
Primary	72 (25.9%)	18 (19.1%)	54 (29.3%)
Secondary and above	52 (18.7%)	21 (22.3%)	31 (16.8%)
Any chronic conditions other than diabetes	273 (98.2%)	94 (100.0%)	179 (97.3%)	.11
Any ADL limitation	172 (61.9%)	64 (68.1%)	108 (58.7%)	.13
Any IADL limitation	270 (97.1%)	93 (98.9%)	177 (96.2%)	.20
Caregiver characteristics
Age (y)	61.8 (12.0)	60.3 (11.9)	62.5 (12.0)	.14
Sex				.56
Male	74 (26.6%)	23 (24.5%)	51 (27.7%)
Female	204 (73.4%)	71 (75.5%)	133 (72.3%)
Highest education				.90
No formal education	30 (10.8%)	10 (10.6%)	20 (10.9%)
Primary	57 (20.5%)	16 (17.0%)	41 (22.3%)
Secondary and above	191 (68.7%)	68 (72.4%)	123 (66.8%)
Housing type				.53
1- to 3-room flat/public rental flat	78 (28.1%)	27 (28.7%)	51 (27.7%)
4-room or above flat/condominium/private flat	189 (68.0%)	65 (69.1%)	124 (67.4%)
Bungalow/semi-detached/terrace house	11 (4.0%)	2 (2.1%)	9 (4.9%)
Perceived financial adequacy^b				.73
More than adequate	12 (4.4%)	2 (2.1%)	10 (5.4%)
Adequate	149 (54.2%)	54 (57.4%)	95 (51.6%)
Occasionally adequate	61 (22.2%)	20 (21.3%)	41 (22.3%)
Usually inadequate	53 (19.1%)	17 (18.1%)	36 (19.6%)
Any chronic condition	220 (79.1%)	74 (78.7%)	146 (79.3%)	.90
Self-rated health				.88
Excellent	14 (5.0%)	6 (6.4%)	8 (4.3%)
Very good	24 (8.6%)	8 (8.5%)	16 (8.7%)
Good	130 (46.8%)	44 (46.8%)	86 (46.7%)
Fair	97 (34.9%)	33 (35.1%)	64 (34.8%)
Poor	13 (4.7%)	3 (3.2%)	10 (5.4%)
Any ADL or IADL limitation	9 (3.2%)	2 (2.1%)	7 (3.8%)	.45
Any physical function difficulty	71 (25.5%)	22 (23.4%)	49 (26.6%)	.56
Provision of care to others	29 (10.4%)	12 (12.8%)	17 (9.2%)	.36
Cohabits with care recipient	240 (86.3%)	78 (83.0%)	162 (88.0%)	.24
Relationship with care recipient				.68
Spouse	64 (23.0%)	23 (24.5%)	41 (22.3%)
Others	214 (77.0%)	71 (75.5%)	143 (77.7%)

Abbreviations: ADL, activity of daily living; IADL, instrumental activity of daily living.

All care recipients have functional limitations (ie, either limitations in ADLs or IADLs).

The proportion with missing values is 6.1% for caregiver psychological resilience, 0.7% for caregiver social support, and 1.1% for perceived financial adequacy.

Among care recipients with diabetes, 17% were not using any prescribed medicines for their diabetes condition, 67% were taking oral medicine(s), 4.3% were taking injectable medicines, and 11.7% were taking both. About 60% of care recipients with diabetes reported having been ever-diagnosed by health care professional with 1 or more diabetes complications (including diabetic neuropathy, diabetic retinopathy, diabetic nephropathy, cardiovascular problems, ulcers, or wounds on feet and/or legs).

Table 2 presents the adjusted associations of care recipient’s diabetes status with caregiver depressive symptoms score from the multivariable linear regression analyses. Caregivers of care recipients with diabetes had a higher depressive symptoms score (by 1.00 unit; β = 1.00, 95% CI, 0.04-1.96) than caregivers of care recipients without diabetes (Model 1). Furthermore, both caregiver expressive social support (β = −0.15, 95% CI, −0.29 to −0.004) and psychological resilience (β = −0.62, 95% CI −0.93 to −0.30) had an inverse association with caregiver depressive symptoms score, indicating that an increase in these constructs was associated with a decline in caregiver depressive symptoms.

Table 2

Association of Care Recipient Diabetes Status With Caregiver Depressive Symptoms Score and Moderation of the Association by Caregiver Social Support and Caregiver Psychological Resilience: Results From Multivariable Linear Regression Analyses^a

Predictors	Model 1	Model 2	Model 3
Predictors	β (95% CI)	β (95% CI)	β (95% CI)
Care recipient with diabetes (reference: care recipient without diabetes)	1.00 (0.04 to 1.96)	8.48 (1.31 to 15.65)	0.60 (−3.22 to 4.43)
Caregiver social support	−0.15 (−0.29 to −0.004)	−0.05 (−0.22 to 0.11)	−0.15 (−0.29 to −0.003)
Caregiver psychological resilience	−0.62 (−0.93 to −0.30)	−0.61 (−0.92 to −0.30)	−0.64 (−1.01 to −0.27)
Care recipient with diabetes × caregiver social support	—	−0.31 (−0.60 to −0.01)	—
Care recipient with diabetes × caregiver psychological resilience	—	—	0.07 (−0.57 to 0.71)

Bold figures indicate β coefficients whose 95% confidence interval does not include the value of 0. Model 1 includes care recipient diabetes status, caregiver psychological resilience, and caregiver social support. Relative to Model 1, Model 2 additionally includes an interaction term between care recipient diabetes status and caregiver social support, and Model 3 additionally includes an interaction term between care recipient diabetes status and caregiver psychological resilience. All three models include care recipient and caregiver characteristics as covariates. All care recipients have functional limitations (ie, limitations in activities of daily living or instrumental activities of daily living).

Table 2 also provides results from models with interaction terms of care recipient’s diabetes status with caregiver expressive social support (Model 2) and with caregiver psychological resilience (Model 3). Expressive social support moderated the association between care recipient’s diabetes status and caregiver depressive symptoms (Model 2: β = −0.31, 95% CI, −0.60 to −0.01). Figure 1 shows the marginal effects of caregiving for care recipients with and without diabetes on caregiver depressive symptoms score by the extent of caregiver expressive social support. With each unit increase in caregiver expressive social support, depressive symptoms score among caregivers of care recipients with diabetes declined, whereas depressive symptoms score among caregivers of care recipients without diabetes remained relatively constant. Consequently, the difference in depressive symptoms score between caregivers of care recipients with and without diabetes reduced with the increase in caregiver expressive social support. There was no evidence for moderation by caregiver psychological resilience (Model 3). The sensitivity analysis, presented in Table 3, considering the binary outcome of caregivers with clinically relevant depressive symptoms (yes/no), also supported the role of caregiver expressive social support as a moderator.

Figure 1.

Average marginal effects of care recipient diabetes status on caregiver depressive symptoms score, moderated by caregiver expressive social support.

Table 3

Association of Care Recipient Diabetes Status With Clinically Relevant Depressive Symptoms Among Caregivers and Moderation of the Association by Caregiver Social Support and Caregiver Psychological Resilience: Results From Binary Logistic Regression Analyses^a

Predictors	Model 1	Model 2	Model 3
Predictors	Odd ratio (95% CI)	Odd ratio (95% CI)	Odd ratio (95% CI)
Care recipient with diabetes (reference: care recipient without diabetes)	1.42 (0.63, 3.19)	9.26 (2.41, 14.13)	0.58 (0.02, 13.61)
Caregiver social support	0.87 (0.75, 1.00)	0.97 (0.82, 1.15)	0.87 (0.75, 1.00)
Caregiver psychological resilience	0.76 (0.58, 0.99)	0.74 (0.56, 0.97)	0.72 (0.52, 0.99)
Care recipient with diabetes × caregiver social support	—	0.68 (0.48, 0.98)	—
Care recipient with diabetes × caregiver psychological resilience	—	—	1.18 (0.68, 2.04)

Bold figures indicate odds ratios whose 95% confidence interval does not include the value of 1. Model 1 includes care recipient diabetes status, caregiver psychological resilience, and caregiver social support. Relative to Model 1, Model 2 additionally includes an interaction term between care recipient diabetes status and caregiver social support, and Model 3 additionally includes an interaction term between care recipient diabetes status and caregiver psychological resilience. All three models include care recipient and caregiver characteristics as covariates. All care recipients have functional limitations (i.e., limitations in activities of daily living or instrumental activities of daily living).

Discussion

The multivariable linear regression analyses conducted in this study confirmed the first hypothesis—caregivers of care recipients with diabetes and functional limitations had a significantly higher depressive symptoms score than those of care recipients only with functional limitations. The second hypothesis was partially supported, with only caregiver expressive social support, but not caregiver psychological resilience, moderating the association of caring for older adults with both diabetes and functional limitations (vs only functional limitations) with caregiver depressive symptoms.

The results of this study, in the context of Hypothesis 1, point to the additional detrimental impact of caring for an older adult with diabetes and functional limitations (vs only functional limitations) on the mental health of their primary family caregiver. This may be reflective of the caregiver’s role in supporting and providing long-term, regular attention and care for diabetes management, including periods of intense care that older adults with both diabetes and functional limitations require at home or from health care services and the worry about complications that may arise from the care recipient not receiving adequate or timely care. This finding is aligned with the previous literature on caregivers of individuals with diabetes or with more complications of diabetes,^19,20 although the comparison group in those studies was either noncaregivers or caregivers of care recipients with less severe diabetes. Several studies have also stated that presence of diabetes among care recipients heavily affects the well-being of both caregivers and care recipients,^22,56 emphasizing the need to orient diabetes management around the care dyad. Practically, this finding suggests that health care services or practitioners managing older adults with both diabetes and functional limitations and long-term or social care services/agencies looking after such older adults should be mindful of the increased psychological vulnerability of their primary family caregivers.

The second hypothesis was partially supported in this study, finding evidence for the moderating role of caregiver expressive social support. Many aspects of expressive social support, including having a close confidant, regular and high frequency of contact, and a high quality of relationship, which have been shown to have positive influence on the prevention of depressive symptoms among caregivers,^25
-29 may have contributed to its moderating role. In addition, the significant direct negative association between caregiver expressive social support and caregiver depressive symptoms that was observed in this study is consistent with previous caregiving studies.^30
-32 A meta-analysis also pointed out that social support, regardless of type, was associated with lower depressive symptoms among caregivers.⁵⁷ Together, these findings provide empirical support for Pearlin et al’s⁹ stress process model, which posits that burden from caregiving can be reduced and buffered by the caregiver’s social support. They also suggest that interventions to enhance expressive social support of caregivers from their family and friends may benefit caregiver mental well-being—such interventions may not only have a direct beneficial effect but also buffer the additional detrimental impact of caring for an older adult with diabetes and functional limitations (vs only functional limitations). From a practical perspective, family members and friends of caregivers of older adults with both diabetes and functional limitations should strive to provide not only instrumental help, such as physical help with care-related tasks, but also expressive social support to the caregiver, through moral support, encouragement, and being a confidant.

The finding that the relationship between caregiving for older adults with both diabetes and functional limitations and caregiver depressive symptoms did not vary by caregiver psychological resilience suggests that resilience may be unable to overcome the adverse psychological impact of the complexity and chronicity of caregiving for older adults with both diabetes and functional limitations. Nonetheless, caregiver psychological resilience had a statistically significant direct negative association with caregiver depressive symptoms in this study, suggesting that it is an important psychological resource for family caregivers irrespective of the care recipient’s diabetes status. Previous studies have also suggested that building and bolstering psychological resilience among caregivers can improve caregiver coping capacity and protect them from negative effects of caring.^38,39 Several intervention studies have shown the positive impact of high psychological resilience among caregivers, which can help diminish the risk of stress and burden.^58,59 This study’s findings also support a focus on building psychological resilience among caregivers of older adults with functional limitations.

Although the focus of this study was on whether the diabetes status of care recipients affects their caregivers, it is important to note the caregivers in the study were themselves relatively old (average age: 62 years; partly owing to the age threshold of 75 years or older, used to identify care recipients), about one-fourth had physical function difficulty, and around three-fourths had chronic diseases themselves. This is concerning because the double burden of caring for older adults with chronic diseases while managing their own has been shown to have detrimental impact on health outcomes of caregivers and their care recipients.^60,61 With rapid population aging and projections of a rise of chronic diseases in Singapore, for example, that 1 in 3 older adults would have diabetes in 2050,⁶² it is likely that care recipient/caregiver dyads where both members are older adults and have chronic diseases, including diabetes, will only increase. Thus, dyadic interventions that target chronic conditions of both older adults and their family caregivers are recommended to improve health outcomes for both parties.⁶³

This study has some limitations. First, a definitive conclusion about the causal direction of the relationship between caregiving for older adults with both diabetes and functional limitations (vs only functional limitations) and caregiver depressive symptoms cannot be drawn from this cross-sectional study. Nonetheless, in the temporal order of the factors being studied, it is unlikely that the presence of depressive symptoms among caregivers led to the development of diabetes among their care recipients. Second, the findings in the context of diabetes may not be generalizable to other chronic conditions that older adults with functional limitations might have and require constant caregiving. The study did, however, account for older care recipients’ other chronic conditions in the regression models. Third, the analysis could not further stratify older care recipients with diabetes in terms of either the severity or duration of diabetes due to inadequate numbers for meaningful comparison (for severity of diabetes) and lack of data (for duration of diabetes). As shown in this study’s data, older care recipients with diabetes are a heterogeneous group, varying in the context of medicines used and diabetes complications, which may affect the specificity of the findings. It is possible that caregivers of older care recipients with more severe diabetes (eg, with complications) may have more depressive symptoms than those caring for older care recipients with less severe diabetes. Future studies with a larger sample size and more detailed data should be considered to answer such questions. Finally, although the higher mental health risk among caregivers for older adults with both diabetes and functional limitations is shown, qualitative studies need to be conducted to understand the specific caregiving tasks or responsibilities contributing to the higher risk.

Conclusion

Among family caregivers of older adults with functional limitations, those caring for older adults who also have diabetes had a higher depressive symptoms score. However, this detrimental psychological consequence was reduced with the increase in caregiver expressive social support. Service providers and family members of family caregivers should be mindful of the additional psychological burden posed by the presence of diabetes among older care recipients and strive to enhance expressive social support of their caregivers.

Footnotes

Author Contributions

Conceptualization – HLQ, AV, RM. Data curation – HLQ, RM. Formal analysis, methodology – HLQ, AV, RM. Project administration – AV, RM. Validation – AV, MMI, RM. Writing – original draft – HLQ. Writing – editing and review – AV, MMI, RM.

Declaration of Conflicting Interests

The authors declare no conflict of interest.

Funding

This research is supported by the Singapore Ministry of Health’s National Medical Research Council under its Health Services Research – Competitive Research Grant (NMRC/HSRG/0095/2018). This work is also supported by the Duke-NUS Signature Research Programme funded by the Ministry of Health, Singapore. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Ministry of Health.

ORCID iD

Ha-Linh Quach

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