The main aim of this study was to assess whether combining SCC with blood biomarkers of neurodegenerative diseases (glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL), and phosphorylated tau181 (p-tau181)) and information on apolipoprotein E (APOE) ε4 increases the predictive value of SCC for risk of all-cause dementia among community-dwelling older adults and whether it contributes to the differentiation between the risk of all-cause dementia and the risk of a first depressive episode in the absence of dementia. The gene discussed is APOE; the disease is dementia.