We identified 20 proteins, ABCA1, ACOT7, ALDH3A2, ATP2B3, CAT, CBS, COMT, DNAJC10, EEF1A2, GAP43, GCA, GGT1, GOLPH3, KIAA1217, PARK7, PRNP, TOM1L2, TTR and VCP, that were mainly linked with dementia, impaired cognition, and mental retardation, as shown in Figure 6B. Furthermore, we mapped the 426 altered proteins against the KEGG PATHWAY mapper, revealing that these proteins were mainly involved in metabolic pathways, neurodegeneration pathways and neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, and Huntington disease (Figure 6C,D). Here, COMT is linked to early-onset autosomal dominant Alzheimer disease.