Neuronal connections have long been suspected to subserve the spread of pathology from one brain area to remote areas in many neurodegenerative diseases, including Alzheimer’s disease.1 Combining molecular imaging for in vivo assessment of Alzheimer’s disease pathology to functional MRI, studies revealed that collections of widespread brain regions communicating together in healthy subjects mirror the stereotyped topography of grey matter atrophy,2 glucose hypometabolism,3 amyloid-β deposition4 and tau deposition,5 in Alzheimer’s disease. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.