BackgroundThe increasing prevalence of cognitive impairment poses substantial risks to older adults, particularly those with chronic diseases. While existing studies have examined the connection between the empty nest phenomenon and cognitive function, few have attempted to consider endogeneity issues within this relationship, with limited attention given to older adults with chronic diseases. This study investigates the impact of empty nest status on cognitive function among rural Chinese older adults with chronic diseases and explores the possible mechanisms underlying this effect.MethodsA cross-sectional study involved 365 older adults aged 60 or above with chronic diseases in rural areas of Shaanxi province, northwest China. Cognitive function was measured using the Mini-Mental State Examination. Multiple regression models and the instrumental variable (IV) method were employed to examine the association between empty nest and cognitive function.ResultsAmong the 365 older adults aged 60 or above with chronic diseases, 43% experienced cognitive impairment. Results from both multiple regression and IV analyses consistently demonstrate a significant association between empty nest status and higher cognitive function scores (β = 1.757, p = 0.007; β = 3.682, p = 0.034, respectively). Mechanism analysis further supports that the positive association may arise from empty nesters receiving more social support from children and friends, and perceiving loneliness experiences as inadequate. Heterogeneity analysis reveals that the association between empty nest status and cognitive function is more pronounced among male adults with chronic diseases.ConclusionsThis study challenges the notion that empty nest status is a risk factor for cognitive decline in older adults with chronic diseases in rural China. The positive impact is attributed to the robust social relationships of empty nesters, encompassing sustained support from their social network, and the absence of an increase in loneliness. Therefore, future interventions aimed at improving cognitive function in older adults may benefit from promoting the development of social relationships.