DOI: https://doi.org/10.21203/rs.3.rs-1889627/v1
Background: In the context of an ageing population and age-related conditions increasing, more and more middle-aged and older persons are involved in grandchildren care. This study aims to investigate the association between intergenerational care based on living arrangements and cognitive function, and explore the mediating effects of social activities and depressive symptoms on grandchildren care and cognition.
Methods: This study selected 5490 Chinese people (≥45 years old) from 2018 China Health and Retirement Longitudinal Study (CHARLS). Participants answered questions related to socio-demographics, Mini-mental State Examination, grandchildren care, the intensity of grandchildren care, Center for Epidemiologic Studies Depression Scale and social activity.
Results: This study found that caring for grandchildren and co-habited with spouse had a significant positive effect on cognitive function among the middle-aged and elderly people (B=0.829, p<0.001). Furthermore, providing intensive or no-intensive children care positively influenced cognitive function. In contrast, providing intergenerational care but not co-habited with spouse negatively affected cognition (B=-0.545, p<0.05). Moreover, caring for grandchildren had direct and indirect effects on cognition, as mediated by social activities and depressive symptoms.
Conclusion: This study highlights that providing grandchildren care and co-habited with spouse is associated with better cognition. The social activities and depressive symptoms act as moderated roles between caring for grandchildren and cognition. The findings emphasize the living arrangement, social engagement and psychological health could be considered when encouraging grandparenting care as a complement to formal care.
Population aging issue is of significant importance which will lead to significant increase in age-related conditions, with far-reaching implications for individuals, society and economy such as cognitive decline [1, 2]. There are about 50 million people in the world affected by dementia, and nearly 10 million new cases are increasing each year, a figure that is forecasted to triple by 2050 [3]. One study predicts that the dementia population will reach 23.3 million by 2030 and the total cost of dementia is expected to reach $114.2 billion in China [4]. Cognitive impairment has become a serious public health problem, placing a heavy burden on the family and society and posing significant challenges to economic development and geriatric care [5]. Therefore, it is urgent to find a solution to this public health issue. Growing evidences showed intergenerational care plays an important role in exploring solutions to this problem [6–10].
In the context of the deepening aging of population [11], more and more older adults take on intergenerational care obligations [9]. In a study of 10 European countries, around half of grandparents provide care for their grandchildren [12]. A study shows that 39% of grandparents have responsibilities for the primary caregiving of their grandchildren in the United States [13]. Intergenerational care is also one of the important forms of diversified family structures and family functions in China. Statistics from China Longitudinal Aging Social Survey (CLASS) 2014 suggest that 40% older people are involved in caring for their grandchildren [14]. Furthermore, some researches proposed that providing grandchildren care had a positive effect on cognitive function [6–10]. Nevertheless, some studies also found that grandparent who provided more intensive grandchildren care showed the lower cognitive scores [15, 16]. Relevant studies available in Chinese people suggested that grandchild caregiving was positively associated with cognition [7, 8]. Although more attention paid to the link between the grandchild caregiving and cognition, the underlying mechanism still need to be further explored.
The relationship between intergenerational caregiving and cognition may be related to social activities and depression, which in turn affects cognition [18–26]. In previous researches, one study of 24 Spanish grandmothers aged 60 and over interviewers showed that in most cases caring for grandchildren could increase their daily activities [17]. Some studies also found that caring for grandchildren could reduce grandparent’s depressive symptoms [18, 19]. Furthermore, numerous studies have demonstrated that older adults who are more socially engaged had higher cognitive function than those with less social engagement [20–23]. Additionally, some studies showed that depression was associated with increased the risk of cognitive decline [24, 25]. However, the relationship and action path among depressive symptom, social activities, caring for grandchildren and cognition remained unknown, which further highlighting the significance of exploring the association between them.
Based on this, we attempt to contribute to the literature on a handful of research further investigation of the association between intergenerational caregiving based on living arrangements and cognitive function in middle-aged and older people. We also further investigate the mediating roles of intergenerational care and cognition. Therefore, we propose the following hypotheses: firstly, there would be a relationship between caring for grandchildren based on living arrangements and cognitive function. Secondly, depressive symptoms and social activities would have mediation effects between caring for grandchildren and cognition in middle-aged and elderly people.
Data for this study were extracted from the China Health and Retirement Longitudinal Study (CHARLS) [26], which is a nationally representative longitudinal survey, hosted by Peking University, with a PPS (Prob-ability Proportional to Size) method, targeting residents aged 45 and above in randomly selected households, and including assessments of the social, economic, and health circumstances. The national baseline survey for CHARLS was conducted in 2011 with 17,708 individual participants from 150 counties of 28 provinces and it has been followed up every two to three years since. CHARLS aims to collect a set of high-quality microdata representative of Chinese households and individuals aged 45 and older to meet scientific and policy research needs on aging- related issues [26].
The data was used in our study from the CHARLS 2018 survey, with a total of 19,528 respondents. This study involves three modules of the database: basic information, households, health status and functioning, we selected 5490 valid participants after screening and eliminating samples with incomplete variables.
The cognitive function was measured by the Chinese version of the Mini-mental State Examination (MMSE) [27]. The MMSE consists of 24 items that assess orientation, episodic memory, attention and computational power, language and visuospatial processing. The total score ranges from 0 to 30, with higher scores representing better cognitive function [28]. In CHARLS 2018, orientation was measured by time (day, month, year, season, and date of the week) and location (state, county, city or town, floor of the building, name of the location) identification, ranging from 0 to 10 points. Episodic memory was tested using the immediate and delayed word recall methods, both of them ranged from 0 to 3 points. The attention and computational power were assessed by asking participants to calculate 100 minus 7, and keep minus 7 continuously for five times (0–5 points). Language skills were measured by naming objectives, repeating a sentence, following orders, reading skills and writing a sentence (0–8 points). The visual construct was measured by redrawing a picture accurately which had been displayed previously (0–1point).
Grandparent caregiving was measured by the following questions in the CHARLS 2018 questionnaire: (1) During last year, did you or your spouse spend time in taking care of your grandchildren? Takes the value of 1 if caregiving is provided and 0 if it is not or no grandchildren. (2) How many hours per week did you spend in taking care of your grandchildren? The intensity of grandchild care was measured by categorical variables: none (0 h); non-intensive grandchild care (1–39 h); and intensive grandchild care (≥ 40 h) [18].
The mediating variables of this study were social activities and depressive symptoms. According to CHARLS 2018, social activities was defined as any activities that respondents were participated in, such as interacting with friends; playing mah-jongg/chess/cards or attending community clubs; providing help for family/friends/neighbors who do not living together; attending a sport/social/other club; taking part in community-related organizations; participating in voluntary or charity work; caring for a sick or disabled adult outside the household; attending an educational or training course; stocking investment and using the internet or others. Frequency of participation in social events was defined by asking the respondents “How often did you do these activities in the last month?” If the answer is not regularly are assigned a value of 1, almost every week are assigned a value of 2, almost daily are assigned a value of 3. Social activities intensity was measured by adding up the total score for the frequency of participation in each social activity. If not attending any social activities, takes a value as 0. The range of frequency of social activities were from 0 to 33. Depressive status was measured by the 10-item Center for Epidemiologic Studies Depression Scale (CES-D). This scale has high reliability and validity in Chinese population [29]. The scale consists of 10 items. Each item used a four-point Likert scale, negative symptoms are assigned as rarely or none of the time (< 1 day) = 0, some or a little of the time (1–2 days) = 1, occasionally or a moderate amount of the time(3–4 days = 2, most or all of the time (5–7 days) = 3. On the contrary, two positive symptoms take values of 3, 2, 1, and 0. The scale’s score is between 0 and 30, with higher scores indicating higher level of depressive symptoms.
Control variables were added to this study, including age (≥ 45 years), gender (female = 0, male = 1). Number of types of chronic diseases was measured by whether the respondent reported having following chronic diseases: hypertension, dyslipidemia, diabetes or high blood sugar, cancer or malignant tumor, chronic lung disease, heart problem, liver disease, kidney disease, stomach or other digestive diseases, stroke, memory-related disease, psychiatric problem, arthritis or rheumatism and asthma (none = 0; one type of chronic disease = 1; two types of chronic disease = 2; three types of chronic disease and above = 3). Self-reported health status (very poor = 1, poor = 2, fair = 3, good = 4, very good = 5). Life satisfaction (completely satisfied = 5, very satisfied = 4, somewhat satisfied = 3, not very satisfied = 2, not at all satisfied = 1).
In this study, all the data analysis and processing were carried out using the IBM SPSS Statistics version 25. Mann-Whitney U test was performed to test differences between providing grandchildren care and non-providing grandchildren care. Multivariate linear regression analysis was performed to examine the effect of caring for grandchildren on cognitive function. Finally, the bootstrap method was used to analyze the mediation effects of social activities and depressive symptoms between providing intergenerational care and cognitive function.
Table 1 reported the basic characteristics of the whole respondents and the comparison of non-caregivers and caregivers subgroups. Of the whole participants, the median age of participants was 67 years old. The median score of cognitive was 21 and the median score of depressive symptoms was 7. Moreover, most participants have no chronic diseases (51.6%), were somewhat satisfied with life (51.9%), and most of them reported health status were fair (47.0%).
|
Variable |
Total |
Caring for grandchildren |
p |
|
|---|---|---|---|---|
|
n (%) |
No n (%) |
Yes n (%) |
||
|
5490 (100.0%) |
3250 (59.2) |
2240 (40.8) |
||
|
Cognitive function median (P25, P75) |
21 (16, 25) |
20 (15, 24) |
22 (18, 26) |
0.000 |
|
Social activity median (P25, P75) |
0 (0, 3) |
0 (0, 3) |
1 (0, 3) |
0.000 |
|
Gender |
0.071 |
|||
|
female |
2850 (51.9) |
1720 (52.9) |
1130 (50.4) |
|
|
male |
2640 (48.1) |
1530 (47.1) |
1110 (49.6) |
|
|
Age median (P25, P75) |
67 (63,73) |
70 (65, 76) |
65 (62, 69) |
0.000 |
|
Number of types of chronic diseases |
0.735 |
|||
|
0 |
2834 (51.6) |
1666 (51.3) |
1168 (52.1) |
|
|
1 type |
1596 (29.1) |
963 (29.6) |
633 (28.3) |
|
|
2 types |
649 (11.8) |
379 (11.7) |
270 (12.1) |
|
|
3 types and above |
411 (7.5) |
242 (7.4) |
169 (7.5) |
|
|
Self-reported health status |
0.014 |
|||
|
Very poor |
521 (9.5) |
296 (9.1) |
225 (10.0) |
|
|
Poor |
616 (11.2) |
353 (10.9) |
263 (11.7) |
|
|
Fair |
2583 (47.0) |
1516 (46.6) |
1067 (47.6) |
|
|
Good |
1357 (24.7) |
825 (25.4) |
532 (23.8) |
|
|
Very good |
413 (7.5) |
260 (8.0) |
153 (6.8) |
|
|
Depressive symptoms median (P25, P75) |
7 (3, 13) |
8 (4, 14) |
7 (3, 13) |
0.001 |
|
Life satisfaction |
0.724 |
|||
|
Completely satisfied |
288 (5.2) |
175 (5.4) |
113 (5.0) |
|
|
Very satisfied |
1675 (30.5) |
989 (30.4) |
686 (30.6) |
|
|
Somewhat satisfied |
2847 (51.9) |
1667 (51.3) |
1180 (52.7) |
|
|
Not very satisfied |
466 (8.5) |
292 (9.0) |
174 (7.8) |
|
|
Not at all satisfied |
214 (3.9) |
127 (3.9) |
87 (3.9) |
|
|
Caring grandchildren and co-habited with spouse |
0.000 |
|||
|
No |
3250 (100.0) |
621 (27.7) |
||
|
Yes |
0 (0.0%) |
1619 (72.3) |
||
|
Caring grandchildren and not co-habited with spouse |
0.000 |
|||
|
No |
3250 (100.0) |
1619 (72.3) |
||
|
Yes |
0 (0.0%) |
621 (27.7) |
||
There were significant differences between non-caregivers and caregivers on most characteristics. The median age of those providing intergenerational care was 65 years old. Overall, 40.8% of grandparents provided grandchildren care. Among these participants those who provided grandchildren care, most of them were co-habited with spouse (72.3%). And the differences of cognitive function and depressive symptom between caregivers and non-caregivers were statistically significant (P < 0.001). Compared with non-caregivers, caregivers scored significantly higher in cognitive function, and lower rate of depressive symptoms. Furthermore, social activities, self-reported health status also had significant differences between non-caregivers and caregivers.
As shown in Table 2, caring for grandchildren and co-habited with spouse had a significant positive effect on cognitive function of the middle-aged and elderly people after controlling the confounding variables (B = 0.829, p < 0.001). In contrast, caring for grandchildren but not co-habited with spouse had a significant negative effect on cognition of the middle-aged and elderly people (B=-0.545, p < 0.05).
|
Variable |
Cognitive function |
|
|---|---|---|
|
Β (95%CI) |
p |
|
|
Intergenerational care based on living arrangements (reference: no care) |
||
|
Caring grandchildren and co-habited with spouse |
0.829 (0.498, 1.160) |
0.000 |
|
Caring grandchildren not co-habited with spouse |
-0.545 (-1.001, -0.089) |
0.019 |
|
R2 adjusted |
0.213 |
|
| Adjusted for age, gender, number of types of chronic diseases, depressive symptoms, self-reported health status, life satisfaction, social activities. | ||
As shown in Table 3, for those participants who co-habited with spouse, the provision of intensive children care was more likely associated with increased in cognition than those providing no children care or non-intensive children care.
On the contrary, providing intensive grandchildren care showed greater declines in cognitive function for those did not live with spouse. Nevertheless, providing non-intensive children care and not co-habited with spouse did not pass the statistical significance test, the regression coefficient was negative, indicating a harmful effect on caregiver’s cognitive function.
|
Variable |
Β (95%CI) |
p |
|---|---|---|
|
Intensive of grandchildren care (reference: no care) |
||
|
Caring grandchildren and co-habited with spouse |
||
|
Non-intensive children care |
0.783 (0.348, 1.219) |
0.000 |
|
Intensive children care |
0.843 (0.428, 1.258) |
0.000 |
|
Caring grandchildren not co-habited with spouse |
||
|
Non-intensive children care |
-0.281 (-0.902, 0.340) |
0.375 |
|
Intensive children care |
-0.696 (-1.342, -0.050) |
0.035 |
|
R2 adjusted |
0.213 |
|
| Adjusted for age, gender, number of types of chronic diseases, depressive symptoms, self-reported health status, life satisfaction, social activities. | ||
Table 4 model 1 showed that the upper and lower bounds of bootstrap 95% confidence interval of the social activities’ effect did not contain 0, so it is considered that social activities played a mediating role between caring for grandchildren and cognitive function. Model 2 showed that the upper and lower bounds of bootstrap 95% confidence interval of the depressive symptoms’ effect did not contain 0, so there was also a mediating effect of depressive symptoms between caring for grandchildren and cognitive function.
From Fig. 1 model 1, it can be seen that caring for grandchildren has a significant positive effect with cognitive function without mediating variables (B = 0.608, p < 0.001). After adding social activities as the mediating variable into the model, caring for grandchildren still has a significant positive effect on cognitive function of middle-aged and elderly people (B = 0.500, p < 0.01). Figure 1 model 1 also reported that caring for grandchildren had a positive effect on social activities (B = 0.204, p < 0.01). Moreover, social activities had a significant positive effect on cognitive function (B = 0.526, p < 0.001), which meant the higher frequency of social engagement, the better cognitive function.
As shown in Fig. 1 model 2, when depressive symptoms were added as a mediating variable into the model, caring for grandchildren still had significant positive association with the cognitive function (B = 0.502, p < 0.01). What’s more, caring for grandchildren had a significant negative effect on depressive symptoms (B= -0.627, p < 0.001). Depressive symptoms had significant negative impact on cognitive function (B= -0.167, p < 0.001), which meant the lower scored depressive symptoms, the higher scored cognitive function.
Therefore, the social activities and depressive symptoms partially mediated the effect between caring for grandchildren and cognitive function in middle-aged and elderly people.
|
Pathway |
Effect |
BootSE |
BootLLCI |
BootULCI |
|---|---|---|---|---|
|
Model 1 |
||||
|
Direct effect |
0.500 |
0.153 |
0.200 |
0.800 |
|
Indirect effect |
0.107 |
0.035 |
0.038 |
0.176 |
|
Model 2 |
||||
|
Direct effect |
0.502 |
0.154 |
0.199 |
0.805 |
|
Indirect effect |
0.105 |
0.029 |
0.048 |
0.166 |
| [ Insert Fig. 1 here] | ||||
| Figure 1 The conceptional framework of the mediation models. | ||||
| All models were adjusted for age, gender, number of types of chronic diseases, self-reported health status, life satisfaction. | ||||
| * p < 0.05, ** p < 0.01, *** p < 0.001 | ||||
Our findings showed that providing intensive children care and co-habited with spouse was more positively associated with cognition compared with those who provided no children care or non-intensive children care. Moreover, social activities and depressive symptoms partially mediated the effect between taking grandchildren care and cognition of middle-aged and elderly people.
This study showed that grandparents played a key role in China’s childcare system. There was 40.8% middle-aged and elderly people provided varying degrees of intergenerational care. The result of this study was similar to those of the studies conducted in CLASS 2014 [14] and another study [30]. This trend is due to China’s traditional culture and the concept of filial piety, the grandparent has moral responsibility for his children and grandchildren [31]. Moreover, the conflict between work and child care for mothers is intense, and the high rate of women's labor force participation in China [32]. Therefore, Chinese parents need to rely on grandparents to help them balance work and childcare. Furthermore, in rural China, due to the surplus of agricultural labor [31], adult children often migrate to city in search of better employment opportunities and leaving their children with grandparents [33]. Additionally, there is a serious lacking of formal daycare facilities of children in China [34].
This study suggested that social activities and depressive symptoms played intermediary roles between caring for grandchildren and cognitive function in middle-aged and elderly people. Our finding was consistent with a study which demonstrated that higher frequency engaged in social interaction with lower risk of cognitive decline [35]. As well as consistent with some studies showed that providing grandchildren care could reduce the depressive symptoms [17, 30, 36] and improve the cognitive function of the older adults [7, 8, 10]. A cohort study showed that depression was a risk factor of dementia [37]. A study by Vinkers et al. also found cognitive impairment associated with exacerbation of depressive symptoms [24]. What’s more, some studies showed that caring for grandchildren can promote mental health in older adults [30, 36]. Thus, caring for grandchildren could help grandparent get the emotional support, reduce the depressive symptoms and then improve their cognition. Social activities also played a key role in the relationship of the provision of grandchildren care and cognition. Based on the role reinforcement theory, caring for grandchildren as a social role provided grandparents emotional support from grandchildren and made social connections, gaining social integration and satisfaction from social participation [38, 39]. One pilot RCT, which included social activities as an intervention component, the cognitive function of older adults was significant improved [40]. Another study showed that social engagement can be viewed as a cognitively stimulating form of daily activity [41]. Moreover, providing grandchildren care increased grandparents' opportunities for social engagement, made grandparents gain more social support, enhanced their emotional health and thus promoting their cognition in social interactions [25, 30].
Caring for grandchildren and co-habited with spouse could improve cognition in middle-aged and elderly Chinese people. Especially, providing intensive grandchildren care and co-habited with spouse was associated with better cognition. Grandparenting is a particularly good example of a social role. Cognition can be maintained due to its positive nature [42]. This is consistent with the earlier studies, which showed that caring for grandchildren was positively associated with cognition in middle-aged and elderly people [7, 8]. Moreover, a study showed that the intensive grandchildren care is associated with lower depressive symptoms [18]. In addition, A study suggests that older adults without a spouse are at greater risk for depression than those with a spouse [43]. The presence of a spouse can facilitate emotional communication and emotional support for older adults, thus counteracting some of the potential risks of depression [30]. Empirical researches provided the evidence that physiological stress and depressive symptoms are the risk factors of cognitive decline [44, 45]. Therefore, co-habiting with spouse and providing intergenerational care, the spouse could relieve some of the physical and psychological burden, reduce the risk of depression thus improve the cognition of the grandchild caregivers. In contrast, our findings suggested that providing intergenerational care but not co-habited with spouse was associated with a decline in cognitive function in middle-aged and older people. A study in Europe pointed that intensively engaged in grandchildren care had lower cognitive function than the others [16]. It can be physically and psychologically demanding that helping another person with daily activities [42], which may increase stress on caregivers, limit their social engagement, thus negatively affecting cognitive function [15].
The CHARLS questionnaire cannot determine the grandparent and grandchildren's living situation, it is not possible to analyze the effect of intergenerational caregiving on caregiver’s cognition in intergenerational families. Moreover, caregiver status is defined by the hours per week spent caring for the child and whether the caregiver cohabite with spouse. However, no distinction is made between co-parenting caregivers and guardians, and between participating caregivers and primary caregivers due to the database limitation. In addition, the MMSE is a self-reported screening scale, and a clinical diagnosis of cognitive impairment is not available.
The present study highlights that providing grandchildren care and co-habited with spouse is associated with better cognition. The social activities and depressive symptoms play mediating roles between intergenerational care and cognition. In the context of the deepening aging of population and age-related conditions increasing, more and more old people participant in intergenerational care. The findings emphasize the living arrangements, social engagement and psychological health could be considered when encouraging grandparenting care as a complement to formal care.
Acknowledgements
Thanks for all participants of the National School of Development workshop in Peking University and thanks for their efforts in the China Health and Retirement Longitudinal Study (CHARLS) of 2018.
Authors’ contributions
We thank XH and YX designed research; XH, GQ, JZ and YX conducted research; XH analyzed data and wrote the manuscript; YX revised the paper, JZ and GQ had primary responsibility for the final content. All authors revised it critically for important intellectual content.
Funding
Not applicable.
Availability of data and materials
The database (CHARLS2018), which is used in this paper, is publicly available.
(http://charls.pku.edu.cn/en).
Ethics approval and consent to participate
Ethics approval for the study was granted by the Ethical Review Committee of Peking University. The IRB approval number is IRB00001052-11015. Informed consent was obtained at the time of participation. All methods of this study were performed in accordance with the relevant guidelines and regulations. All experimental protocols were approved by Institutional Review Board at Peking University.
Consent for publication
Not applicable.
Competing interests
Authors declare no competing interest.