A single-cell transcriptomic atlas of six anatomical regions in the aged human brain with and without Alzheimer disease (AD) provides clues to cellular vulnerability to disease, a study in Nature reports. Various region-specific subtypes of excitatory and inhibitory neurons were reduced in brains from people with AD and shared elevated expression of genes in the reelin signalling pathway. In addition, astrocytes showed a high number of differentially expressed genes between the two groups across all regions. Gene expression in astrocytes was associated with cognitive resilience, highlighting an important role of these cells in AD vulnerability.