Fig.1

Overview of study concept a We selected post mortem Formalin Fixed Paraffin Embedded (FFPE) samples from eight different brain regions from individuals of the 90 + Study, aged 90 and older. All consecutive cases available to the lab from 2017 to 2019 were considered. After removing cases based on co-pathologies and data quality, a total of 47 individuals were included in the final analyses for this paper (see Methods). b Neuropathological scoring was carried out to define the Alzheimer’s Disease (AD) severity score as well as its three subscores: NIA-AA A (amyloid beta), B (neurofibrillary tangles), and C Score (neuritic plaques). c Small biopsy punches were used to assure precision tissue dissection from FFPE. Before and after LFB-H&E staining was carried out to control the accuracy of the dissected region. d After DNA extraction and bisulfite conversion, we used the Illumina 850 k EPIC BeadChip and followed the manufacturer’s protocol to determine DNA methylation. e Data analysis focused on cell type deconvolution from bulk data. AD Alzheimer’s disease, LFB-H&E Luxol fast blue hematoxylin and eosin, NIA-AA National Institute of Aging Alzheimer’s Association, Olig Oligodendrocytes, OPC Oligodendrocyte Precursor Cells