The Impact of Mental Health on Cognitive Functioning among Community-Dwelling Elderly and Its Mechanisms: A Large-Scale Cross-Sectional Study of 10,370 Participants

Abstract Background To delve deeply into the impact of depression and anxiety on cognitive function in the elderly, as well as the mediating mechanisms involved. Methods Data were derived from the baseline survey of a cross-sectional study on the health status of community-dwelling elderly individuals in Guangxi, China, conducted from July 2022 to July 2023. Valid data from 10,370 elderly individuals aged 60 years and older were analyzed. Cognitive function of the elderly was assessed using the Memory Impairment Screen (AD8), while depression symptoms and anxiety symptoms were evaluated using the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder Scale-7 (GAD-7), respectively. Univariate and multiple linear regression analyses were conducted to explore the influencing factors of cognitive function in the elderly. Pearson correlation analysis was used to investigate the correlations among depression symptoms, anxiety symptoms, cognitive function, and related factors. Chain mediation analysis was performed using AMOS 26.0 software to explore the mechanisms of the effects of age and mental health on cognitive function among community-dwelling elderly individuals. Results A total of 10,370 elderly individuals were surveyed in this study, including 4,590 males and 5,780 females, aged 65–103 years (mean age: 73.41 ± 6.67 years). The mean score on the AD8 scale was 1.05 ± 1.71, with 2,484 (23.95%) individuals identified as having mild cognitive impairment and 1,705 (16.44%) individuals with cognitive dysfunction. The mean score on the PHQ9 scale was 1.22 ± 2.30, with 580 individuals (5.59%) classified as having mild depression, 121 (1.17%) with moderate depression, 33 (0.32%) with moderately severe depression, and 7 (0.07%) with severe depression. The mean score on the GAD7 scale was 0.70 ± 1.89, with 368 individuals (3.55%) identified as having mild anxiety, 78 (0.75%) with moderate anxiety, and 22 (0.21%) with severe anxiety.Multivariate linear regression analysis showed statistically significant differences in the effects of gender, age, category, years of education, marital status, PHQ9, and GAD7 on cognitive function among the elderly (P < 0.05). There was a positive correlation between PHQ9 scores and AD8 scores (r = 0.361, P < 0.001) in the elderly, as well as a positive correlation between GAD7 scores and AD8 scores (r = 0.287, P < 0.001). Additionally, a strong positive correlation was observed between PHQ9 scores and GAD7 scores (r = 0.690, P < 0.001). Age was also positively correlated with AD8 scores (r = 0.213, P < 0.001).The study further revealed a chained mediating effect of age, mental health, and cognitive function among the elderly. The total effect estimate was 0.055, which was statistically significant (P < 0.001). The direct effect estimate was 0.04, indicating a significant positive and direct impact of age on AD8 scores (P < 0.001). Conclusions The finding that mental health plays a partial mediating role between age and cognitive function provides a new perspective for understanding the decline in cognitive function. This discovery holds significant theoretical and practical implications for improving the mental health and cognitive function of the elderly, which can contribute to the development of more effective intervention measures and enhance the quality of life for the elderly.