As an independent test of the power of BioAge to predict normal chronological age, we applied this biomarker to an independent cohort of prefrontal cortex samples from non-demented individuals (GSE1572). This gene expression data were used to qualitatively describe aging in an earlier study [3]. BioAge score in these samples strongly and significantly correlated with chronological age of the subjects in the range from 26 to 106 years (ρ = 0.75, p = 8E–7) (Fig. 2B). In addition, BioAge corresponded to the second principal component in the GSE1572 dataset (ρ = 0.90, p = 4E–11), validating that aging is a major reproducible source of variance in gene expression in PFC. Similar prediction of chronological age using gene expression was recently proposed [33].
