**Figure 3.** **Comparison of methylation clocks for sorted brain cells.** (**A**) The seven methylation clocks applied on matched samples from six children (≤18 years old) and 15 adults (separated by the vertical dotted line). Samples include unsorted brain tissue, and FACS sorted cells that are positive (NeuN+) and negative (NeuN-) respectively for a neuronal marker. The dashed diagonal line shows y=x, a perfect correlation between methylation age and chronological age, for reference, and the diagonal dotted lines display the regression lines of chronological age to methylation age for the three sample types. (**B**) Boxplot of age acceleration for the three sample types for the pediatric samples (boxplot for adult samples in Supplementary Figure 4). For the PhenoAge methylation clock, the NeuN+ cells have significantly lower age acceleration than NeuN- (adj. p = 0.024) and unsorted brain (adj. p = 0.0003).