Assessing cognitive impairment in home-dwelling Chinese elders aged 80+: a detailed survey of 13,000 participants focusing on demographic factors, social engagement, and disease prevalence

Introduction Cognitive Impairment (CI) in the elderly, encompassing conditions ranging from Mild Cognitive Impairment (MCI) to dementia, represents a growing public health concern globally. This study aims to investigate the prevalence and correlates of CI among individuals aged 80 and above. Methods The study conducts 13,027 elderly individual’s door-to-door surveys, followed by the cross-tabulation of analysis data, logistic regression analysis, and health condition assessments to examine various determinants of CI. Results The current study’s key findings demonstrate sub-statical correlations between CI and various factors, including educational attainment, marital status, and gender. Pronounced differences are evident between urban and rural demographics. Furthermore, aspects of social engagement, notably communication proficiency and sensory capabilities, exhibit a strong association with CI. Logistic regression analysis highlights that residing in rural areas (Odds Ratio [OR] = 0.637) and being female (OR = 0.71) are linked to a decreased risk of CI. In contrast, behavioral and health-related variables present a complex picture. Specifically, aggressive behavior (Adjusted OR = 1.881) and symptoms of depression (Adjusted OR = 0.549) contrast with conditions such as asthma (OR= 2.857) and cerebral infarction (OR=1.348), which elevate the risk of CI. Intriguingly, hyperlipidemia (OR= 0.671) appears to confer a protective effect against CI. Conclusion The study highlights the complexity of factors affecting CI in the elderly, advocating for a comprehensive approach to understanding and managing cognitive health.


Introduction
Cognitive Impairment (CI) manifests as a spectrum of cognitive deficits in the elderly, impacting essential domains such as orientation, memory, calculation, attention, language, executive function, reasoning, and visualization abilities (1).This condition is broadly classified into mild cognitive impairment (MCI) and dementia, based on severity (2).Dementia, particularly prevalent among the older population, has emerged as a significant public health concern due to its substantial socio-economic and healthcare implications.For instance, in 2010, the prevalence of dementia in the U.S. population aged over 70 was approximately 14.7% (3).
In China, the incidence rate of dementia for individuals aged 60 and above is reported to be 9.9 cases per 1000 person-years.Alzheimer's disease and related dementia show an increasing trend with age, evidenced by an 8% prevalence in those over 65, rising sharply to about 43% in adults over 85.Projections indicate that the number of individuals in the 'oldest old' category (over 80 years) will triple by 2050 (4).The prevalence of MCI, a transitional state between the normal cognitive aging process and early dementia, exhibits significant variability in China, with estimates ranging from 9.7% to 23.3% (5).
CI in older adults, a condition characterized by memory deficits, learning challenges, and impaired concentration, significantly compromises their quality of life.This impairment not only elevates the risk of dementia and mortality but also stems from a multifactorial etiology, including vascular issues, neuronal degeneration, and strokes (6).Empirical evidence indicates that around 10% of individuals who suffer strokes had pre-existing dementia, a figure that increases in post-stroke scenarios, especially among recurrent stroke patients (7).Central to its progression are factors such as gender (8), advancing age (9), smoking habits (10), limited mental and physical engagement (11), and reduced social interactions, which cumulatively exacerbate cognitive decline.Moreover, cardiovascular metabolic risk factors (12), including diabetes, hypertension, metabolic syndrome, and other vascular disorders (13), are strongly correlated with an acceleration of cognitive decline.Additional factors contributing to this impairment range from atrial fibrillation and depression to obesity (14), traumatic brain injury, hearing loss, alcohol misuse (15), and exposure to air pollution (16).The spectrum of cognitive impairment in the elderly spans from mild, often undiagnosed deficits to more severe conditions like dementia.
The Mini-Cog, a concise and innovative tool for dementia screening, combines two simple cognitive tasks: recalling three words and drawing a clock.Created by Borson and colleagues in 2000 (17)., this approach improves upon the Clock Drawing Test (CDT) and the Mini-Mental State Examination (MMSE), as evidenced by multiple studies.With an average administration time of just 3 minutes, it is faster than the MMSE and is preferred by elderly patients due to its omission of potentially uncomfortable orientation questions.It has been validated as an effective tool for screening dementia and cognitive impairment in various settings, including preoperative clinic evaluations.
Understanding the trajectory of cognitive impairment over a lifetime is crucial for developing strategies to prevent its onset and slow its progression towards dementia.However, data regarding the association of cognitive impairment with demographic factors, social engagement, and disease prevalence, particularly in individuals aged 80 and above, remains sparse.Our study aims to bridge this gap by investigating whether cognitive impairment, as detected using the Mini-Cog test, correlates with demographic characteristics, social engagement levels, and disease prevalence in older adults.To this end, we have designed a cohort study targeting adults aged 80 years and above.

Methods
Our research was a comprehensive 8-month-long (April to December 2022) population-based, cross-sectional study conducted in Lishui District, Jiangsu, China (Figure 1).The study commenced with an initial cohort of 13,823 individuals aged 80 or older, identified with the assistance of the Lishui Civil Affairs Bureau.The research team comprised a total of 57 researchers who underwent uniform training to ensure their proficiency in basic assessment knowledge and skills.This training was essential to guarantee that each of the 57 doorto-door researchers adhered to unified assessment requirements, thereby ensuring the scientific accuracy of the research data.
As the study progressed, an additional 1,293 elderly individuals were identified and incorporated, thereby expanding our study population.However, the dynamics of participant involvement underwent notable changes over the course of the study.Specifically, of the initial participant group, 263 individuals passed away, 1,553 were not found at their registered residences during follow-up visits, 54 opted to withdraw from the study, 58 relocated to nursing homes, 47 were hospitalized, and 113 remained unreachable for various reasons.After adjusting for these participant changes, the study successfully completed evaluations with a total of 13,027 elderly participants, as shown in Figure 1.

Measurements
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Cognitive impairment
In our study, we utilized the Mini-Cog assessment method as outlined by Borson et al. (15) to screen for cognitive impairment (18).This evaluation awards one point for each item correctly recalled and up to two points for the clock-drawing task, culminating in a maximum score of five points.Data were collected for both the recall and clock-drawing tasks for all participants.However, consistent with Borson's scoring protocol, the clock-draw performance was scored only for patients who recalled between one and two words.'Cognitive Impairment' was defined as a score of two or less, and 'No Cognitive Impairment' as a score greater than two, in accordance with the methodology established by Borson et al.

Disease survey questionnaire
To elucidate the correlation between CI and diverse medical conditions, a survey encompassing various diseases was executed.The surveyed conditions included hypertension, hyperglycemia, hyperlipidemia, cardiac disorders, cerebral infarction, leg and foot discomfort, pain, gastrointestinal diseases, back pain, stroke, pulmonary ailments, asthma, gout, osseous disorders, cancer, ocular conditions, renal diseases, gallstones, rheumatism, among others.

Data analysis
In this investigation, we utilized SPSS software (IBM Corp., Armonk, NY, USA; Version 25.0.0.0) for a comprehensive analysis of the data.The threshold for statistical significance was established at p < 0.05.Depending on the nature of the measurement scales, group comparisons were executed using either Student's t-tests for continuous variables or chi-square tests for categorical variables.
In our univariate analyses, we scrutinized variations in mini-cog scores across diverse demographic categories within the population aged 80 years and older.This analysis revealed significant disparities, highlighting the diversity within this age group.Moreover, the study assessed the predictive capability of mini-cog scores for the likelihood of disease onset using binary logistic regression analysis, applying a Forward Stepwise method.The significance level for this analysis was maintained at p < 0.05.

Demographic factors in CI
These figures indicate the necessity for targeted approaches to address CI within various demographic segments (Table 1).The table details demographics and health characteristics of individuals with and without CI.In urban areas, 2244 individuals (75.6%) have no CI, while 6674 (66.4%) do.Rural areas have 725 (24.4%) without impairment and 3384 (33.6%) with it.Regarding marital status, the majority of non-impaired individuals are married (57.5%), while a significant proportion of impaired individuals are widowed (48.2%).The Flowchart of the study.
For education, a notable 78.2% of cognitively impaired individuals are illiterate.In terms of income, most in both groups rely on wages/ pension.Living situations show 34.5% of non-impaired and 34.7% of impaired individuals living alone.Gender-wise, more females (55.5%) have CI compared to males.Disease presence is nearly equal in both groups, and mental illness is found only among the cognitively impaired (4.1%).

Demographic, economic, social CI influences
In our logistic regression analysis examining the impact of various factors on CI (Table 3), significant associations were found across demographic, behavioral, health, insurance, work ability, and social relationship variables.Residence in a rural area was associated with a decreased likelihood of the outcome, as evidenced in both unadjusted (OR = 0.637, 95% CI (0.58, 0.7) and adjusted models (OR = 0.672, 95% CI (0.595, 0.759), with statistical significance (p < 0.001).Similarly, female gender was significantly linked to a lower likelihood of the outcome in both models (Unadjusted: OR = 0.71, 95% CI (0.654, 0.771); Adjusted: OR = 0.708, 95% CI (0.652, 0.769), p < 0.001).Income sources showed varying impacts; income for children was significant only in the unadjusted model (OR = 1.183, 95% CI (1.009, 1.386), p = 0.038), while pension income showed a strong negative association in both models.Behavioral and health factors presented contrasting associations with the outcome.Aggressive behavior increased the likelihood of the outcome (Adjusted OR = 1.881, 95% CI (1.082, 3.27), p = 0.025), whereas depression symptoms were inversely associated (Adjusted OR = 0.549, 95% CI (0.32, 0.944), p = 0.03).Basic health conditions, specifically having a disease, were not significant in the unadjusted model but showed a significant positive association after adjustment (OR = 1.304, 95% CI (1.172, 1.45), p < 0.001).Participants with New  Work ability and social relationships also demonstrated significant impacts.A marked decline in work ability and deterioration in social relationships were strongly associated with the outcome.The most pronounced effects were observed in participants with markedly worse work ability (Adjusted OR = 0.214, 95% CI (0.139, 0.329), p < 0.001) and those only able to recognize household members (Adjusted OR = 0.166, 95% CI (0.069, 0.399), p < 0.001).These findings emphasize the multifaceted nature of CI and the importance of considering a broad range of factors in its understanding and management.
Conversely, Hyperlipidemia and Waist/Lower Back Condition were associated with a reduced likelihood of CI.Hyperlipidemia showed a significant protective effect in the adjusted model (OR= 0.671, 95% CI(0.458,0.985),though it was not significant in the unadjusted model.The waist/lower back condition consistently showed a negative association in both models (Unadjusted OR=0.578, 95% CI(0.4,0.834); Adjusted OR=0.581, 95% CI (0.402,0.839).Difficulty in Leg Movement was also found to moderately increase the likelihood of CI (Unadjusted OR=1.42, 95% CI(1.101,1.83);Adjusted OR=1.408, 95% CI(1.091,1.817).These findings highlight the varied influence of different health conditions on the risk of CI, underscoring the need for tailored approaches in its management and prevention.

Discussion
These figures highlight key differences and potential correlations between gender and various such as social (19), educational, and health factors with CI (20), where social factors (21) include urbanrural residence, marital status, income source, living conditions.The urban-rural divide (22) in cognitive scores could be attributed to differences in access to healthcare, educational opportunities, and lifestyle factors.Marital status, particularly being married, seems to confer a protective effect on cognitive health, potentially due to social support and shared responsibilities (23).
The strong link between educational attainment (24) and cognitive function underscores the importance of education in cognitive health.Higher education levels may provide better cognitive stimulation and access to information on health-promoting behaviors.Income source, particularly from pensions or wages, suggests a possible link between financial stability and cognitive health (25).
Living arrangements' influence on cognitive function highlights the role of social interactions and support systems in maintaining cognitive health (26).The gender differences observed point towards potential biological and social factors influencing cognitive health.
There is a complex relationship between health condition and functional abilities among the study participants.While certain domains, such as communication, vision, hearing, life skills, work ability, time/space orientation, person orientation, and social interaction, showed significant associations with functional abilities, the presence of disease did not exhibit a significant impact.These findings highlight the multifaceted nature of functional abilities and the need for a comprehensive assessment.
CI or dementia refers to a clinical syndrome characterized by challenges in memory, language, and behavior, resulting in limitations in performing daily activities.Moreover, the results of this study reveal that the capacity to execute daily life skills (27), maintain occupational effectiveness, and preserve orientation in time and space emerged as notable determinants of functional abilities.
The significant association of rural residence with a decreased likelihood of the outcome contrasts with common perceptions and may reflect underlying socioeconomic and healthcare disparities (28).Gender differences, particularly the lower likelihood of the outcome among females, align with previous studies suggesting gender-specific risk factors and resilience mechanisms.The differential impact of income sources, notably the significant negative association of pension income, could be indicative of socioeconomic stability's influence on health outcomes.The contrasting associations of behavioral factors, such as aggressive behavior (29) and depression (30) symptoms, with the outcome underscore the complexity of behavioral health's role.The significant association after adjustment for having a disease highlights the importance of considering comorbid conditions in evaluating health outcomes.
The substantial impact of social insurance types, especially the New Rural Cooperative Medical Insurance, suggests that healthcare accessibility and quality are critical determinants of health outcomes.These findings emphasize the importance of functional and social aspects in health, going beyond mere clinical or behavioral considerations.This aligns with the growing recognition of holistic health approaches, integrating physical, mental, and social well-being.
The results of this study underscore that respiratory and circulatory conditions (31), such as asthma (32) and cerebral infarction (33), significantly elevate the risk of CI.The observed increase in odds ratios for asthma and cerebral infarction emphasizes the need for vigilant monitoring and management in patients with these conditions.
Conversely, our study revealed a notable protective effect of hyperlipidemia and waist/lower back conditions (34) against CI.This counterintuitive finding, particularly for hyperlipidemia, which is often considered a risk factor for various health issues (35), suggests a potential area for further investigation.It raises questions about the underlying mechanisms that might confer this protection and how these might be leveraged in clinical practice.
The moderate increase in the likelihood of CI associated with difficulty in leg movement (36) could be indicative of broader mobility or lifestyle-related factors impacting health outcomes.This observation aligns with studies emphasizing the importance of physical mobility in overall health (37).
This study conducted an extensive door-to-door survey, meticulously targeting individuals aged over 80 years within a specific locale, with the objective of performing a thorough evaluation.The investigation revealed a range of demographic, social, and health challenges prevalent among older adults living in their own homes and examined their association with CI.This research thus offers a foundational dataset for future studies.It is crucial to acknowledge the limitations of this study, notably its focused demographic and methodological approach.Further investigation into the health status disparities between elderly individuals residing independently and those in nursing homes or healthcare facilities is essential.Additionally, the selection of participants should incorporate considerations of regional differences.

Conclusion
The study reveals correlation between CI and demographic and health factors.Urban-rural differences are evident, for social engagement playing a significant role.Logistic regression analysis highlights rural residence and female gender as protective against CI, while behavioral and health factors present a complex picture.Hyperlipidemia shows a protective effect.These findings underscore the multifaceted nature of CI and the importance of comprehensive assessment and intervention strategies.

TABLE 1 Demographic
Factors in CI.

TABLE 2
Cross-Tabulation of Social Engagement and CI.
2073Basic Self-Care, Assistance: Able to manage personal basic life affairs (e.g., eating, toileting) and can wash up with reminders.

TABLE 3
Demographic, Economic, Social Factors associated with CI.
Model A: unadjusted; Model B is an adjusted model, incorporating all relevant variables(Residence, Gender, Income, Aggressive Behavior, Basic Health Condition, Social Insurance,Work Ability, Social Relationships); CI: confidence interval; (p ≤ 0.05).

TABLE 4 Disease
Factors Influencing CI.