Association of Low Emotional and Tangible Support With Risk of Dementia Among Adults 60 Years and Older in South Korea

Key Points Question Are low levels of social support associated with risk of dementia in older adults? Findings In this cohort study of 5852 adults 60 years and older, low emotional support was associated with an increased risk of dementia; however, low tangible support was not. Low emotional support was associated with a 61% increased risk of all-cause dementia and a 66% increased risk of Alzheimer disease in women but not in men. Meaning These findings suggest that older women with low emotional support should be considered a vulnerable population at risk for dementia and be provided with sufficient empathetic understanding and listening as well as material aid or behavioral assistance.


Introduction
Social support, a qualitative aspect of social relationships, affects physical and mental health via behavioral, psychological, and physiological pathways; high social support promotes healthpromoting behaviors, self-efficacy, adaptive coping styles, and stress-buffering while also modulating hypothalamic-pituitary-adrenal axis, cardiovascular reactivity, and the immune system. 1 Low social support was associated with various adverse health outcomes such as coronary heart disease, 2 depression, 3 and mortality. 4 Social isolation in late life has been accepted as a potentially modifiable risk factor for dementia. 5 Social isolation could be determined by the level of social support that reflects the quality and function of social relationships. 1 However, the association of social support with risk of dementia has been debated. Low social support has been associated with risk of dementia in some prospective studies [6][7][8][9] but not others. [10][11][12][13] The conflicting results of these studies might be attributable, at least in part, to a limited evaluation of social support. First, most of the previous prospective studies did not differentiate the subtypes of social support; rather, they evaluated the level of social support using only a single-item questionnaire with categories such as "being satisfied with relationships," "getting help from others," or "being understood by others" [6][7][8][10][11][12] or using multiple-item questionnaires without differentiation of the subtypes. 13 However, the association of social support with the risk for dementia may be different by its subtypes because neural substrates of social support differed by their subtypes. 14 The 2 major subtypes of social support include emotional support, which provides empathy, caring, or understanding, and tangible or instrumental support, which provides help, aid, or assistance with tangible needs. 1 In a prospective study from Japan, 9 emotional support from friends or neighbors was associated with reduced risk of dementia, but tangible support from friends or neighbors was not associated with the risk of dementia in older adults with disabilities. A replication study is needed to clarify whether association of social support with dementia risk differed by the subtypes of social support in healthy older adults. Furthermore, most previous studies have not considered the effect of sex on the association between social support and the risk of dementia. Because women have been found to be more dependent on emotional support from a widespread social network than men during their lifetimes, 15 the level of each subtype of social support and its association with the risk for dementia may differ by sex.
In this prospective cohort study of a representative population of older South Korean adults, we compared the associations of emotional and tangible support with risk of dementia. In addition, we examined whether these associations with risk of dementia are dimorphic by sex.

Study Design, Setting, and Participants
The Korean Longitudinal Study on Cognitive Aging and Dementia (KLOSCAD) is a population-based prospective cohort study of older adults. 16 November 30, 2020). For the present analyses, we included 5852 participants from the baseline assessments after excluding those who were diagnosed as having dementia (n = 408), severe psychiatric disorders including major depressive disorder (n = 323), or major neurological disorders (n = 15) or those who did not complete the assessment for social support (n = 220). Among the 5852 participants, 4603 (78.7%) completed the first follow-up assessments; 3783 (64.6%), the second; 3097 (52.9%), the third; and 2306 All the participants were fully informed about the study protocol and provided written informed consent. This study was approved by the institutional review board of the Seoul National University Bundang Hospital. We followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies.

Assessments of Social Support
We evaluated the level of perceived emotional and tangible social support using the Medical Outcomes Survey social support survey. 17 The level of each subtype of social support is rated by the sum of the scores of 4 items. For emotional support, we asked how often someone was available "who you can count on to listen to you," "to confide in," "to share your worries with," and "who understands your problems." For tangible support, we asked how often someone was available "to help you if you confined to bed," "to take you to the doctor," "to prepare your meals," and "to help with daily chores." Each item was rated on a Likert scale from 1 (none of the time) to 5 (all of the time).
The mean (SD) scores of the total 5852 participants were 15.1 (4.3) for emotional support and 16.3

Assessments of Covariates
Trained research nurses assessed sociodemographic factors (age, sex, educational level), healthpromoting or -aggravating behaviors (current alcohol consumption, smoking, and the level of physical activities), burden of comorbidities, depressive symptoms, and economic status. We defined the low level of physical activities as less than 600 metabolic equivalent task minutes per week of exercises, 25 high comorbidities as 5 points or greater on the Cumulative Illness Rating Scale score, 26 depression as 16 points or greater on the Geriatric Depression Scale score, 27 and economic disadvantage as being covered by the National Medicaid insurance.
In face-to-face interviews, research nurses evaluated the marital status, presence of cohabitants, and current occupational status as indicators for the social network of each participant.
They also evaluated the total amount of social activities (mean hours per month) such as familial gatherings, religious and peer group connections, and volunteer activities during the past year.

Statistical Analysis
We calculated the age-and sex-adjusted prevalence and incidence of low social support by direct standardization method using the 2010 National Census data. We compared the baseline characteristics of participants according to sex using a χ 2 test for categorical variables and an unpaired t test for continuous variables. We compared the sex-adjusted characteristics by the level of social support using logistic regression and analysis of covariance. We then calculated the age-and sex-adjusted incidence rates of all-cause dementia and AD by sex and the subtype of support. We compared the incidence of all-cause dementia and AD by sex and the subtype of support using the χ 2 test. To examine whether LES and LTS at baseline assessment are associated with the risks of incident all-cause dementia and AD, we used Cox proportional hazards analyses adjusted for age, sex, educational level, alcohol consumption, smoking, physical activity, comorbidities, depression, economic status, marital status, cohabitants, occupation, and social activities. As sensitivity analyses, we performed the Cox proportional hazards analyses by entering social support of increasing strata (<25th, 25th-75th, and >75th percentiles) and continuous variables. We also used Cox proportional hazards analyses entering the interactions between sex and each type of social support as independent variables. All statistical analyses were performed using SPSS Statistics, version 19.0 (IBM Corporation). Two-sided P < .05 indicated statistical significance.

Results
Among the 5852 participants in the baseline assessment (2537 men

Discussion
In a previous study using claims data for older adults with disabilities from a long-term care insurance system in Japan, 9 emotional support was associated with a 15% lower risk of incident dementia by 15% in women and an 18% lower risk of incident dementia in men, whereas tangible support did not change the risk of incident dementia. However, to our knowledge, the differential association between emotional and tangible support with the risk of dementia has not been investigated in older adults. This study demonstrated that LES was associated with increased risks of all-cause dementia and AD by approximately 40% among older women but not men. However, LTS was not associated with the risks of all-cause dementia and AD in both sexes. Emotional support-that is, the feeling of being understood, cared for, reassured, and provided with chances for emotional expression-may protect against the development of dementia by buffering the effect of stressful events. 28 Chronic repeated stress may lead to synaptic suppression and dendritic remodeling in AD-related brain   29 In a previous study, 30 the association between LES and cognitive decline was mediated by hippocampal atrophy. In contrast to the emotional support that may cover a wide range of stressful events, tangible support may buffer stress from a specific need associated with a certain event. 28 This study also found that the association of LES with the risk of dementia differed by sex.
Because women have been shown to be more dependent on a wide range of emotional support resources under stressful situations compared with men, 15 the shrinkage of a supportive social network may put women at greater risk for dementia than men, which may contribute at least in part to the sex-dimorphic association of LES with risk of dementia. Compared with men who depend on close relationships such as a few family members, women depend on larger and more variable social networks. 31,32 With advancing age, the size of social networks other than family decreases faster than that of a family network. 33 Therefore, women may become more vulnerable to LES and the subsequent risk of AD as they grow older. However, the role of sex in the association between LES and dementia risk should be interpreted cautiously, because some of our interaction analyses were not statistically significant.
Previous epidemiological studies 34,35 have found a higher incidence of AD in women than in men, which may be the result of sex differences in risk factors. 36 Furthermore, women are known to be more vulnerable to AD-related pathology (eg, β-amyloid and tau deposition) than men. 37 The present study found that the sex-specific association was independent of covariates as well as the higher incidence of LES in women than in men. Therefore, along with the other sex-specific risk factors, the sex-dimorphic association of LES with risk of AD may contribute to the high incidence of AD in women. Further investigation is needed to clarify the role of LES in the association between sex and risk of dementia.
The findings of the present study suggest that previous conflictive findings regarding the association of social support with dementia risk may be attributable to the partial or ambiguous assessment of social support. These conflicts become more distinct when these previous studies are classified by subtype of social support. In line with the results of the present study, studies that only evaluated the emotional aspect of social support (eg, being understood or listened to by others) 6,8,9 reported a significant protective association of social support with risk of dementia, whereas studies that only examined the tangible aspect of social support (eg, getting help or being cared for by others when sick) 9,12 reported no such association. Meanwhile, studies using single-or multiple-item questionnaires without clear distinctions between emotional and tangible subtypes (eg, being satisfied with relationships or having good relationships) 7,10,11,13 inconsistently reported associations between social support and dementia risk. By evaluating and differentiating multiple subtypes of support using comprehensive and structured assessment tools, the findings of the present study suggest that the association between social support and risk of dementia largely depends on the subtype of social support.
Our findings further suggest that the cognitive function of women with LES should be tracked carefully in primary care and outpatient clinics. In terms of public health, we also suggest that older women with LES should be considered a population at risk for dementia and should therefore be provided with emotional support from their community. Few studies have examined the effectiveness of enhancing social activities against cognitive decline in cognitively normal older adults. Two studies that used activities focusing on cognitive and physical functions but not emotional support found no significant improvement in cognition. 38,39 Another study that used activities strengthening emotional support found a limited but significant improvement in cognition. 40 Future investigations are needed to develop intervention strategies focusing on emotional support and to identify the effectiveness of those strategies to prevent dementia in women. Limitations Several limitations should be acknowledged in this study. First, we evaluated the level of perceived social support but not the level of actual social support received. Although a previous study 17 reported that perceived social support could reflect the degree of availability of support more accurately than the support received, the possible discrepancies between perceived and received social support should be noted. Second, although we adjusted covariates such as marital status, cohabitants, occupation, and frequency of participation in social activities that may be related to social relationships, we did not directly evaluate the sources of social support and the size of social networks. Third, our findings should be generalized with caution because social relationships and their association with the risk for dementia may differ by race and ethnicity, culture, and social structures. Our findings should be replicated in different settings or countries with various social environments. Fourth, this study is also subject to an attrition bias. Additionally, whether LES was the prodromal condition or a risk factor for dementia was unclear because the follow-up duration by the onset of dementia was relatively short.

Conclusions
To our knowledge, this cohort study is the first to demonstrate that the association between social support and risk of dementia is differentiated by the subtypes of social support and sex. The level of perceived emotional support is worthy of being included in the risk assessment of dementia in older adults, particularly in women.