Abstract

Apolipoprotein E (APOE) ε4 is a recognized genetic risk factor for dementia and has been explored in connection with depression. However, the interplay between APOE ε4, depressive symptoms, and cognitive function remains unclear. Given the rising prevalence of dementia and late-life depression among older adults, this study focused on individuals aged 65 and older. We classified 514 neurology outpatients into two groups based on their APOE ε4 carrier status and categorized cognitive function into three levels—subjective cognitive decline, mild cognitive impairment, and dementia—following DSM-5 diagnostic criteria. Cognitive function was assessed using the Seoul Neuropsychological Screening Battery-II (SNSB-II), while depressive symptoms were measured with the Geriatric Depression Scale (GDepS). We analyzed differences in depressive symptoms based on APOE ε4 carrier status and levels of cognitive impairment, as well as their interaction. The results revealed that APOE ε4 carriers had significantly higher levels of depressive symptoms compared to non-carriers (p=.032), aligning with previous research. Additionally, depressive scores varied significantly across cognitive impairment groups (p=.018), with post hoc analyses indicating that individuals with dementia reported higher depressive scores than those with mild cognitive impairment. Although the main effects were significant, the interaction effect was not. These findings suggest that older adults carrying the APOE ε4 allele may need regular monitoring and proactive mental health interventions for depressive symptoms, even in the absence of significant cognitive decline. Furthermore, this study provides essential data for developing personalized mental health management models that take genetic risk factors for depression into account.