Background: Since limited, specific assessments of social environments have previously been used, with the effect of a change in social interaction proving rare in previous studies, this study sought to clarify the specific association between changes in social interaction and symptoms of dementia.Methods: The participants were elderly people, aged > 60 years, from a suburban community. All the participants formed part of the investigation from 2008 to 2011. The Index of Social Interaction was used to measure social interaction among elderly people. Data of dementia were obtained from Health and Welfare Center of local government. The chi-square test and a logistical regression analysis were used to examine the relationship between changes in social interaction and dementia.Results: There were 321 participants without missing data. The results showed that "reading newspapers" was a positive change in social interaction in relation to the risk of dementia (odds ratio = 3.45, confidence interval: 1.04-11.45).Conclusion: This study focused on changes in social interaction and found that a positive change could help prevent dementia. Specifically, this study indicated that elderly people's engagement with the social environment and in intellectual activities would prevent dementia. Copyright (C) 2016, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC.