The enrichment analysis of the 153 dysregulated proteins in subjects with dementia compared with those in individuals with MCI (Figure 3C, Table S4) showed that they are mainly enriched in the immune system (adjusted p = 3.54 × 10−11); 15 of these proteins were shown to be involved in the cytokine–cytokine receptor interaction pathway (adjusted p-value = 0.0001), including CCL28, CCL27, CXCL13, CD40, IL4R, IL1B, IL17C, IL17D, TNFRSF11A, TNFRSF14, and TNFRSF13B. The gene discussed is IL17D; the disease is dementia.