Critically, the expression levels of six of these 20 putative AD genes (PGAP6, ARHGAP1, CD163, CYP4F3, LAMP1, SLC11A1) correlated with neuropsychological testing scores in the dementia subjects, suggesting that the genes associated with disease severity of dementia can be different from those with altered expression levels in AD as compared to CN subjects. This evidence concerns the gene SLC11A1 and Alzheimer disease.