Abstract: Objective To explore the effect of social isolation, sleep quality and their interaction on cognitive function in the elderly. Methods From October to December 2021, stratified sampling method was used to select 520 elderly people from Bengbu City. Lubben Social Network Scale, Pittsburgh Sleep Quality Index and Montreal Cognitive Assessment-Basic were used to evaluate the social isolation, sleep quality and cognitive function of the elderly, and Logistic regression analysis and interaction analysis were used to analyze the association among them. Results A total of 506 elderly were enrolled in the study finally. Among the 506 elderly, 166(32.8%) presented with social isolation, 138(27.3%) with sleep disorders, and 116(22.9%) with cognitive dysfunction. After adjusting age, education level, living status, marital status, and combined chronic diseases, the results of binary Logistic regression analysis showed that social isolation(OR=3.637, 95%CI:2.174-6.205) and sleep disorder(OR= 3.308, 95%CI:1.970-5.556) were the influencing factors of cognitive dysfunction in the elderly. The results of interaction analysis showed that the risk of cognitive impairment in the elderly with social isolation and sleep disorder was 11.811(95%CI:5.923-23.552) times higher than that in the elderly without social isolation and sleep disorder, with a relative excess risk due to interaction(RERI) of 8.167(95%CI:0.199-16.134), with an attributable proportion of interaction(AP)of 0.640(95%CI:0.379-0.902), with the synergy index(S) of 3.276(95%CI:1.374-7.814). Conclusions Social isolation and sleep quality are the risk factors of cognitive function in the elderly, and their effects on cognitive function have additive interaction.

Key words: social isolation, sleep quality, cognitive function, aged