We downloaded already-processed data from BrainSpan (http://download.alleninstitute.org/brainspan/Methylation/) and Spiers, et al.23 from GEO (under accession GSE58885) and obtained composition estimates per sample using the same 405 probes and five cell types as above. Comparisons between composition estimates and age and/or brain region were performed using linear regression. Re-analysis of Spiers, et al.23 for a main effect of age, adjusting for the composition estimates from the 5 cell types, was performed using limma46.
