Purpose: This study aimed to identify the risk factors for dementia that influence the health-related quality of life (HRQoL) in late middle-aged adults. Methods: A cross-sectional descriptive study was conducted with subjects from G Metropolitan City. Using convenient sampling methods, a total of 221 nurses were recruited. The data gathered included knowledge of dementia, anxiety, preventive behaviors, the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K), and responses to the International Physical Activity Questionnaire (IPAQ)-short form Patient Health Questionnaire (PHQ)-9, and Short Form-12 Health Survey Questionnaire version 2 (SF-12v2). Descriptive statistics, Pearson's correlation co- efficients, and hierarchical multiple regression analysis were utilized for the data analysis. Results: The results revealed that physical HRQoL was significantly associated with dementia-related anxiety, sleep quality, and depression, while being positively influenced by preventive behaviors. Mental HRQoL showed significant associations with dementia-related anxiety, sleep quality, depression, and physical activities, and positively impacted by preventive behaviors. Monthly income and memory emerged as the most significant variables affecting physical HRQoL, explaining 29.9...