of unnatural causes, death was likely related to aging issues other than the health of the brain. Since non-demented individuals likely died from causes largely unrelated to neurodegeneration, each individual death is conceptually a random event along the generalized brain aging trajectory. In AD patients, the drivers of aging were stronger and variable across the cohort; and death was generally related to the health of the brain that became incompatible with life regardless of the chronological age. The extrapolated BioAge of normal patients would not reach the highest AD levels until the age of 140 years. Thus, AD can be viewed as an aberrant aging of the brain, which retains the gene expression hallmarks of normal aging combined with additional patterns associated with pathological drivers of the disease and response of the brain tissue to disease-related processes.
