The relationship between hearing loss and cognitive function in the elderly: the mediating effect of social isolation

Abstract

Background

Hearing loss is an important factor affecting cognitive function in the elderly. However, the relationship between hearing loss, social isolation, and cognitive function remains unknown. This study aims to explore the relationship between hearing loss and cognitive function in the elderly and analyze the mediating role of social isolation.

Method

From June to November 2023, a total of 450 elderly people (Male 161, Female 289) were recruited in Tangshan City by convenience sampling, including 252 young-old, 168 middle-old, and 30 very old. The study used the general demographic questionnaire, hearing handicap inventory for the elderly-screening (HHIE-S), Montreal Cognitive Assessment (MoCA), and Lubben social network scale (LSNS-6) to collect cross-sectional data from the elderly participants. Data analysis was performed using SPSS 24.0 and PROCESS macro.

Result

The mean age of older adults was 72.77 ± 7.96years, ranging from 60 to 87 years old. The hearing loss score of the elderly was 10.00 ± 7.75 points, the cognitive function score was 24.06 ± 4.22 points, and the social isolation score was 15.73 ± 4.83 points. A negative correlation was observed between hearing loss and cognitive function in the elderly (r=-0.418, P < 0.001). In addition, hearing loss was also negatively correlated with social isolation in the elderly (r=-0.385, P < 0.001). However, a positive correlation was found between social isolation and cognitive function (r = 0.537, P < 0.001). Furthermore, hearing loss in the elderly was found to not only directly affect their cognitive function but also indirectly affect their cognitive function through the mediating effect of social isolation, with a mediating effect value of -0.170.

Conclusion

This study revealed that hearing loss, social isolation and cognitive function in the elderly are not optimistic. Hearing loss can not only directly affect cognitive function but also indirectly affect cognitive function through the mediating effect of social isolation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-025-06261-5.

Introduction

The aging population poses a major challenge to global public health, and hearing loss has emerged as a growing concern among the elderly [1]. However, hearing loss has an insidious onset [2]. As age increases and physiological functions deteriorate, the incidence of hearing loss in the elderly also increases [3]. Data from the World Health Organization (WHO) show that approximately one-third of the elderly aged ≥ 65 years have varying degrees of hearing loss [4]. Hearing loss in the elderly refers to the decline in hearing function in both ears due to aging, genetic factors, noise damage, and disease [5]. Notably, hearing loss in the elderly is irreversible and exerts a negative impact on their quality of life, social relationships, mental health, and cognitive function [6, 7]. The 2020 report of the Lancet Commission shows a link between hearing loss and cognitive decline. The report pointed out that the risk of cognitive impairment in elderly people with hearing loss is 31.7% [8]. Relevant epidemiological evidence shows that hearing loss is an independent factor affecting cognitive decline [9]. Golub’s research found an increased risk of cognitive dysfunction per 10 dB of worsening of hearing loss [10]. Cognitive function is defined as the ability of the higher-order nerves of the cerebral cortex to acquire, transform, and use objective information from the outside world. Cognitive function is a health factor that is significantly impacted during the aging process. As age increases, the prevalence of cognitive impairment shows a growing trend [11]. Impaired cognitive function refers to the abnormal decline in cognitive function, affecting an individual’s daily or social abilities. A survey based on the health status of Chinese elderly people revealed that 31.5% of Chinese elderly suffered from cognitive dysfunction [12]. Impaired cognitive function has emerged as a long-term health problem that primarily affects the elderly, thereby increasing the burden of social care [13]. Moreover, social isolation is an important health risk factor for the elderly [14]. Social isolation refers to a state in which an individual has less contact with the outside world, lacks a sense of social belonging and social satisfaction, and lacks high-quality social relationships. Social isolation is used to measure the size of an individual’s social network, the number of social connections, and the frequency of participation in social connections. A previous study reported that an incidence of social isolation of 27.5% among the elderly in China [15]. The gradual shrinking of the social network of the elderly is an unavoidable reality. Due to the changes in social roles and the influence of chronic diseases, the elderly’s social interactions are limited, resulting in a decline in their ability to establish social relationships, making them a high-risk group for social isolation [16]. Elderly people with hearing loss are more likely to feel frustrated or embarrassed due to communication difficulties, which may lead to their withdrawal from social situations and social isolation [17]. Hearing loss makes it more difficult for the elderly to communicate with other people, thereby weakening the willingness of others to interact with the elderly, causing the elderly to suffer from social exclusion and increasing the risk of social isolation[18].In addition, in order to cope with hearing loss, the elderly themselves will experience changes in speech and behavior, causing them to feel social fatigue or even social phobia, further reducing their desire to participate in social activities. Long-term social isolation will lead to a lack of language and emotional stimulation in the elderly, which may have a direct negative impact on brain structure and function, thereby increasing the risk of cognitive dysfunction [19]. Previous studies have often used independent perspectives to analyze the current status and factors influencing hearing loss, cognitive function, and social isolation in the elderly. However, only a few studies have explored the influencing pathways between hearing loss, cognitive function, and social isolation in the elderly in China. Such research is warranted, considering that China is the world’s largest developing country with the largest elderly population. Therefore, this study aims to explore the relationship between hearing loss and cognitive function in the elderly in China, as well as the mediating role of social isolation. The following hypotheses are made: (1) elderly people with hearing loss are more likely to have cognitive dysfunction; (2) social isolation plays a mediating role between hearing loss and cognitive dysfunction in the elderly.

Method

Study design and participants

This study is an exploratory study, which provides a basis for further research and refers to the methods of similar studies [20–23]. Therefore, this study adopted a cross-sectional research design method. Using convenience sampling, 450 elderly people in Tangshan were selected as research subjects from June to November 2023, including 252 young-old, 168 middle-old, and 30 very old.

Inclusion criteria for this study:

1. Age ≥ 60 years old.

2. Informed consent, voluntary participation and cooperation in the investigation.

Exclusion criteria:

1. Currently wearing hearing aids or cochlear implants and other hearing aids.

2. Mental disorders or deafness that prevent cooperation.

Research tools

This study used a self-designed General Information Questionnaire. The general information questionnaire used in this study included gender, age, marital status, educational level, living conditions, smoking status, and chronic disease status [Additional File 1].

The hearing handicap inventory for the elderly-screening (HHIE-S) is widely used to measure hearing loss in Chinese elderly [24, 25]. HHIE-S includes two dimensions, namely social scene (5 items) and emotion (5 items), with a total of 10 items. The total score of the scale ranges from 0 to 40 points, with a higher score indicating a more severe hearing loss. A score of 0 to 8 indicates no hearing loss, a score of 10 to 22 indicates mild to moderate hearing loss, and a score of 24 to 40 indicates severe hearing loss [26]. The Cronbach’s α coefficient of this scale in this study was 0.875.

The Montreal Cognitive Assessment (MoCA) including memory, language, attention, abstract thinking, orientation, visuospatial structural skills, and executive functioning, for a total score of 30. The score of < 26 indicates cognitive dysfunction, while a higher score indicates a better cognitive function [27]. The Montreal Cognitive Assessment is suitable for the economic and cultural context of China. It has been validated in previous studies based on the Chinese population [28, 29]. The Cronbach’s α coefficient of this scale in this study was 0.848.

The Lubben social network scale (LSNS-6) has been widely used to assess social isolation among Chinese elderly [30, 31]. The scale includes two dimensions: family network and friend network. Each dimension contains three items, for a total of six items. Each item is scored from 0 to 5 points, with a total score ranging from 0 to 30 points. A lower score is associated with a higher risk of social isolation. A total score of < 12 points indicates that the elderly are socially isolated, while a score of < 6 points in the family network or friend network dimension indicates family isolation or friend isolation, respectively [32]. The Cronbach’s α coefficient of the scale in this study was 0.860.

Data collection

From June to November 2023, data were collected from the elderly who met the inclusion criteria, ensuring that the participants fully understood the purpose and significance of this study, thereby improving the participation of the elderly and the reliability of the data. The researchers conducted face-to-face surveys and collected data using a unified questionnaire. All personnel involved in data collection received uniform training to ensure they were able to communicate with elderly with potential hearing and cognitive difficulties. Before collecting data, all participants were informed of the purpose of the survey and that their information would be kept confidential. Each interview took about 15–20 min. The researcher distributed and collected the questionnaires on-site, and the questionnaires were filled out by the respondents. The questionnaires were collected and checked individually; the respondents were requested to fill in the missing items in time. A total of 480 questionnaires were distributed in this study, and 450 valid questionnaires were collected, achieving an effective rate of 93.75% (450/480).

Ethical considerations

This study has been reviewed by the PWU Ethics Committee (ERB2023_0165).

Statistical analysis

IBM SPSS 24.0 software was employed to analyze the research data. Frequencies and percentages were used to describe statistics. The measurement data was described as mean ± standard deviation(x̅±s). This study employed the Pearson test to evaluate the correlation between hearing loss, cognitive function, and social isolation. This study utilized Model 4 in the Process 4.0 program to assess the mediating effect of social isolation on the relationship between hearing loss and cognitive function in the elderly. Moreover, the bootstrap method was used to verify the mediating variable, with a test level of α = 0.05.

Results

General situation of the elderly

A total of 450 elderly people were surveyed in this study, including 161 males (35.8%) and 289 females (64.2%). The age of the elderly ranged from 60 to 87 years old, with an average age of 72.77 ± 7.96 years old. A total of 234 elderly people had spouses while 216 elderly people did not. Table 1 shows the details of the demographic characteristics of the elderly participants.

Table 1.

Demographic characteristics of elderly participants

Category		n	Percentage (%)
Age	60–74(Young-old)	252	56.000
	75–84(Middle-old)	168	37.333
	≥ 85(Very old)	30	6.667
Gender	Male	161	35.778
	Female	289	64.222
Marital Status	No spouse	216	48.000
	Have spouse	234	52.000
Education Level	Elementary school	144	32.000
	Middle School	222	49.333
	Bachelor degree and above	84	18.667
Living Status	Gregarious	246	54.667
	Living alone	204	45.333
Smoking	No	222	49.333
	Yes	228	50.667
Number of Chronic Diseases	≤ 1	138	30.667
	2	228	50.667
	≥ 3	84	18.667

Current status of hearing loss, cognitive function, and social isolation in older adults

The results of this study revealed that the hearing loss score of the elderly was 10.00 ± 7.75 points (mild-moderate hearing loss), with an incidence of 45.8% (206/450). The hearing loss score for males was 11.10 ± 7.81 points, and the hearing loss score for females was 9.38 ± 7.67 points. The cognitive function score of the elderly was 24.06 ± 4.221 points, and the incidence was 30.2% (136/450). The cognitive function score of males was 24.88 ± 3.99 points, and that of females was 23.60 ± 4.28 points. The social isolation score of the elderly was 15.73 ± 4.83 points, with an incidence of 30% (135/450). The social isolation score of males was 15.91 ± 4.75 points, and that of females was 15.64 ± 4.88 points.

Correlation analysis among hearing loss, cognitive function, and social isolation in the elderly

The results of this study showed that the hearing loss scores of the elderly were negatively correlated with their cognitive function scores (r=−0.418, P < 0.001). In addition, the hearing loss scores of the elderly were negatively correlated with their social isolation scores (r=−0.385, P < 0.001). However, the social isolation scores of the elderly were positively correlated with their cognitive function scores (r = 0.537, P < 0.001). Table 2 presents the results in detail.

Table 2.

Correlation analysis among hearing loss, cognitive function and social isolation in the elderly

	Hearing Loss	Social Isolation	Cognitive Function
Hearing Loss	1
Social Isolation	−0.385***	1
Cognitive Function	−0.418***	0.537***	1

* p < 0.05 ** p < 0.01 *** p < 0.001

The mediating effect of social isolation on the relationship between hearing loss and cognitive function in the elderly

Model 4 in PROCESS was used for linear regression analysis. The control variables were set as the main demographic characteristics, with hearing loss as the independent variable, social isolation as the mediating variable, and cognitive function as the dependent variable. Figure 1 shows the mediating effect of social isolation between hearing loss and cognitive function. The results of Model 1 and Model 2 in Table 3 indicate that hearing loss in the elderly has an impact on their cognitive function (β=−0.418, P < 0.001) and social isolation (β=−0.385, P < 0.001). After social isolation was introduced as a mediating variable in Model 3, both hearing loss and social isolation scores were found to have an impact on cognitive function (β=−0.248, P < 0.001. β = 0.442, P < 0.001). The partial regression coefficient of hearing loss increased from − 0.418 to −0.248, indicating that social isolation plays a partial mediating role between hearing loss and cognitive function in the elderly. Table 3 presents the results in detail.

Fig. 1.

The mediating effect of social isolation on the relationship between hearing loss and cognitive function

Table 3.

Regression analysis results of hearing loss and social isolation on cognitive function of the elderly

Predictor variables	Model 1		Model 2		Model 3
	β	t	β	t	β	t
Hearing Loss	−0.418	−9.279	−0.385	−8.821	−0.248	−5.952
Social Isolation					0.442	10.630
R 2	0.174		0.148		0.341
Adjusted R 2	0.173		0.146		0.338
F	94.661***		77.811***		115.657***

Model 1: Cognitive function, Model 2: Social isolation, Model 3: Cognitive function

* p < 0.05 ** p < 0.01 *** p < 0.001

In order to explore the potential mediating effect of social isolation on the relationship between hearing loss and cognitive function, the bootstrap test method was employed and 5000 random repeated samplings were set. The analysis suggested that the 95% confidence interval (CI) generated by the test did not contain 0, indicating that the mediating effect of social isolation on the relationship between hearing loss and cognitive function was statistically significant. Hearing loss can affect cognitive function directly or indirectly through the mediating effect of social isolation, with a direct effect of −0.248 and a mediating effect of −0.170. Table 4 presents the results in detail.

Table 4.

Bootstrap test of the mediating effect of social isolation on the relationship between hearing loss and cognitive function in the elderly

Effect	β	SE	95% CI
			Lower	Upper
Total Effect	−0.418	0.043	−0.502	−0.334
Direct Effect	−0.248	0.042	−0.329	−0.166
Mediating Effect	−0.170	0.022	−0.215	−0.128

Discussion

Current status of hearing loss, cognitive function, and social isolation in the elderly

The results of this study revealed a hearing loss score of 10.00 ± 7.75 points and an incidence of hearing loss of 45.8% in the elderly, which was similar to the results of previous studies [33]. Hearing loss has become the third largest public health problem in the world, and the incidence of hearing loss is significantly accelerating with the aging of the population. According to the 2021 World Hearing Report by the World Health Organization, hearing is the sense that people rely on most when communicating and interacting with each other. The impact of hearing loss can last throughout life. Among the elderly over 60 years old, more than 65% suffer from varying degrees of hearing loss [34]. Although hearing loss is not life-threatening, it can have a negative impact on many aspects of the lives of older people. Hearing loss can reduce quality of life and social opportunities, leading to social isolation and cognitive decline in the elderly, and increasing the risk of dementia [35]. Hearing loss exerts a negative impact on the social function and cognitive function of the elderly [36]. At present, the incidence of hearing loss among the elderly in China is relatively high. The Healthy China Action Plan (2019–2030) sets the maintenance of the hearing health of the elderly as an important indicator for achieving healthy aging [37]. Therefore, community health service personnel should pay more attention to improving hearing health awareness among the elderly and conduct appropriate health education. The elderly with severe hearing loss should be guided to use hearing aids or cochlear implants and carry out auditory training to reduce the impact of hearing loss on their quality of life.

In this study, a social isolation score of 15.73 ± 4.83 points was found among the elderly. The incidence of social isolation among the elderly was 30%, which was similar to the results of previous studies conducted in China [38]. Nonetheless, social isolation remains a prevalent issue among the elderly. Notably, social isolation is characterized by decreased frequency of social interactions, less social contact, and decreased intimacy with family and friends [39]. The rapid development of the internet has greatly impacted the way people interact with each other; however, the lack of digital socialization among the elderly may lead to a digital divide and social isolation [40]. Older people are the most vulnerable to social isolation. Relevant studies have indicated more severe social isolation as age increases, which may be attributed to a greater concurrent disease burden [41]. In addition, studies have shown that long-term social isolation can reduce the amount of physical activity in the elderly, increase chronic stress, and cause the elderly to maintain higher levels of inflammatory biomarkers interleukin-6 and C-reactive protein, accelerating the decline of cognitive function in the elderly[42].Therefore, social isolation in the elderly should be promptly identified, focusing on elderly people with a higher risk of social isolation, and promptly detecting and improving their negative emotions. Specifically, community health service agencies can undertake measures such as organizing regular activities for the elderly, enabling them to meet their emotional and social needs.

In the present study, a cognitive function score of 24.06 ± 4.22 points was found among the elderly, with a cognitive dysfunction rate of 30.2%. These results are similar to the survey results of Zhao [43], indicating poor cognitive function in the elderly. Cognitive function is an important function of the individual brain, involving multiple abilities such as memory, thinking, speech and understanding, and is also one of the indicators for measuring the quality of life of the elderly [44]. Related studies have found that the occurrence of cognitive decline in the elderly is related to multiple factors, such as age, disease, living conditions, and knowledge reserves [45, 46]. Therefore, community health service personnel should pay particular attention to elderly people with low cognitive reserves who live alone, and provide individualized cognitive training according to the degree of cognitive dysfunction, such as memory training, orientation training, language communication skills training, and calculation training. Moreover, community health service personnel should encourage the elderly to engage in reasonable physical exercise, such as aerobic training or game-based sports activities, thereby limiting the decline of cognitive function.

The relationship between hearing loss and cognitive function in the elderly

The results of this study demonstrated a negative correlation between hearing loss and cognitive function in the elderly (r=−0.418). More severe hearing loss in the elderly was associated with a higher incidence of cognitive dysfunction, which is consistent with the research results of Chi Yanyu [47]. Hearing loss in the elderly accelerates the decline of cognitive function and increases the risk of dementia [48].Related studies have found that the risk of cognitive impairment in patients with mild, moderate and severe hearing loss is 2 times, 3 times and 5 times that of the normal population, respectively[49].Increased hearing loss is associated with increases in amyloid-beta and tau proteins, two pathological markers of dementia[50].Epidemiological study identifies hearing loss as one of the most modifiable risk factors for dementia[51]. It is worth noting that cognitive decline may begin when an individual has subclinical hearing loss, so it is urgent to implement early dementia prevention strategies for people at risk of hearing loss [52]. Hearing loss in the elderly is related to aging of the peripheral and central auditory systems. The multisensory system theory states that sensory function plays a crucial role in information processing and is closely associated with the brain’s cognitive network. Hearing loss in the elderly can decrease the activation of the central auditory pathway in the brain, followed by an increase in compensatory activation of the brain’s cognitive control network, leading to auditory-limbic connectivity dysfunction and atrophy of the afferent nerves in the frontal and parietal lobes, ultimately increasing the risk of cognitive decline in the elderly [53, 54]. An animal experiment also confirmed that hearing loss can lead to a decline in cognitive function. C57BL/6J mice developed hearing loss in old age, revealing changes in the ultrastructure of the synapses in the CA3 region of the hippocampus, resulting in a decline in cognitive function [55]. In addition, studies have reported that improving hearing can compensate for the brain’s information-processing ability and thus improve cognitive function. Early intervention in elderly people with hearing loss can effectively alleviate the decline in cognitive function in the elderly population within 3 years [56]. Therefore, community health service personnel should emphasize the screening of hearing conditions in the elderly population in the community for early detection, early diagnosis, and early treatment. These goals are of great significance to reducing hearing loss in the elderly and improving their cognitive function.

The mediating effect of social isolation on the relationship between hearing loss and cognitive function in the elderly

The results of this study show that hearing loss can not only directly affect cognitive function but also indirectly affect cognitive function through the mediating effect of social isolation. Long-term hearing loss may cause individuals to lose their social skills, thereby leading to a decline in cognitive function [57]. As a vulnerable group in society, the elderly suffer from a lower quality of social relationships due to retirement, living alone, and widowhood, leading to a high incidence of social isolation [58]. In particular, when faced with changes in hearing, elderly people are more likely to be unable to extract words from conversations in noisy environments due to decreased attention, resulting in communication difficulties for the elderly, which in turn exacerbates conflicts in their interpersonal relationships, reduces their opportunities to participate in social activities, and increases the risk of social isolation [59]. Long-term lack of language and emotional stimulation may have a direct negative impact on brain structure and function, thereby increasing the risk of cognitive dysfunction in the elderly [60]. In addition, if hearing loss in the elderly remains unaddressed, the condition may worsen, resulting in impaired speech recognition. This may further deteriorate language communication and social skills in the elderly, leading to social isolation [61]. Social isolation can directly cause changes in brain structure related to memory and reduce the brain capacity of the elderly. Socially isolated people exhibit a higher risk of dementia compared to those without social isolation [62]. According to the explanation of the buffering model of social relations, social isolation is essentially a source of stress. Elderly people with social isolation cannot obtain effective social support through social relationship networks to buffer the negative impact of stress[63].In addition, according to the stress theory of cognitive function, individual stress adaptation failure and the resulting stress response will change the structure of the hippocampus in the elderly brain and damage the learning and memory forms mediated by the hippocampus, which may lead to cognitive decline[64].Therefore, family members should support the elderly in using hearing care and hearing aids. Furthermore, community health service personnel can educate the elderly about protecting hearing and ear health, thereby reducing the degree of hearing loss. Additionally, the elderly can be encouraged to actively participate in various social activities, overcoming social barriers and reducing the negative impact of social isolation on hearing loss and cognitive function. Such measures may alleviate hearing loss in the elderly and delay the occurrence of cognitive dysfunction.

Limitations

Nevertheless, the limitations of the present study should be acknowledged. First, the single-center nature of the study may limit the generalizability of the findings to other countries or populations. Second, the data used in this study originated from a cross-sectional survey, so no causal relationship can be established between hearing loss, social isolation, and cognitive function. It is suggested that subsequent studies can adopt longitudinal research methods to further explore the relationship between hearing loss, social isolation and cognitive function. Third, the reliance on self-report questionnaires may introduce response bias, as patients could over- or under-report their hearing loss, social isolation, and cognitive function. It is recommended that future studies use multiple tools for evaluation. Fourth, the proportion of female samples in this study is relatively high, which may bias the research results. It is recommended that future studies pay attention to the male-female ratio of samples during data collection.

Conclusion

This study revealed that hearing loss, social isolation and cognitive function in the elderly are not optimistic. Hearing loss can not only directly affect cognitive function but also indirectly affect cognitive function through the mediating effect of social isolation. This study explores the association mechanism between the three, providing a basis for exploring intervention strategies to delay cognitive decline in the elderly and promote healthy aging.

Abbreviations

HHIE-S

Hearing handicap inventory for the elderly-screening

MOCA

Montreal Cognitive Assessment

LSNS-6

Lubben social network scale

Authors’ contributions

All authors contributed to the study conception and design. Writing-Original Draft Preparation: JINWEN BAI, FANGFANG ZHEN & KUN YANG. Conceptualization: JINWEN BAI, FELINA C. YOUNG & MARIA DELLA C. RANESES. Data analysis: FANGFANG ZHEN, KUN YANG. Writing–Review & Editing: JINWEN BAI, KUN YANG.

Funding

This research received no specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Data availability

The data are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study has been approved by the PWU Ethics Committee (ERB2023_0165) and all procedures were conducted in accordance with the Declaration of Helsinki. All participants gave informed consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.