Summary
A Nature Review proposes that Alzheimer’s disease develops through discrete molecular, cellular and network transitions rather than a single linear cascade from amyloid-β to Tau pathology and neurodegeneration. The framework places amyloid-associated Tau phosphorylation at a pivotal biological threshold.
A peer-reviewed Nature Review proposes a different way to describe how Alzheimer’s disease develops: not as one smooth sequence from amyloid-β accumulation to Tau pathology and then neurodegeneration, but as a series of biological transitions organised around critical inflection points.
Authors Bart De Strooper and Eric Karran argue that these transitions occur when stress-driven loss of cellular homeostasis produces a qualitative change in how cells behave. The resulting altered states can spread through local tissue domains, form a mosaic across the brain and progressively involve vulnerable information-processing centres linked to cognitive performance.
The article was published online on 16 September 2026 as an early-access, accepted version. Nature identifies it as a Review, and says that the version may receive further edits before being replaced by the final Version of Record.
From a linear cascade to biological states
The commonly used description of Alzheimer’s places amyloid-β accumulation at the beginning of a cascade, followed by changes in Tau and neuronal damage. The new framework instead divides disease progression into molecular, cellular and network phases. Each phase represents a different biological state, and movement between states occurs when a threshold is crossed.
In this context, homeostasis refers to the ability of cells and tissues to maintain stable internal conditions while responding to stress. The authors propose that Alzheimer’s progression involves a gradual erosion of this resilience. Once stress exceeds the capacity to compensate, cellular behaviour can shift rather than change continuously in small increments.
The model also gives local brain regions an important role. Disease-related states may emerge in individual tissue domains at different times, producing a patchwork—or mosaic—of affected and less affected areas. As these states accumulate and reach brain centres involved in information processing, their effects may become more closely associated with cognitive decline.
Tau phosphorylation as a pivotal transition
The review identifies the induction of amyloid-associated Tau phosphorylation as a central inflection point. Phosphorylation is a chemical modification in which phosphate groups are added to a protein; for Tau, changes of this kind are associated with a shift in neuronal stress responses.
Within the authors’ framework, this transition separates tissue domains dominated by amyloid-related changes from domains in which neuronal Tau stress responses have emerged. It therefore marks more than another step in a fixed sequence: it represents a change in the biological state of the affected tissue.
This distinction may help explain why the amount and location of pathology do not always map directly onto symptoms. Different brain regions can cross biological thresholds at different times, while the cognitive consequences depend partly on whether vulnerable information-processing centres become involved.
Why the framework matters
The proposed model offers a shared architecture for familial and sporadic Alzheimer’s disease while placing greater emphasis on thresholds, timing and the progressive loss of homeostatic resilience. Familial disease is linked to inherited causes, whereas sporadic disease arises without a single inherited cause; the review argues that both forms can be understood through the same pattern of biological transitions.
The practical significance is conceptual but important. Research and treatment strategies based only on the total burden of amyloid or Tau may overlook when a tissue domain changes state and how far that transition has spread. A threshold-based view instead focuses attention on the timing and location of these shifts, and on the biological capacity that allows cells to resist or absorb stress.
The article is a synthesis and conceptual framework, not a clinical trial or a validated diagnostic system. Its value for patient diagnosis or treatment will depend on future work that can identify these inflection points reliably in living people and determine whether changing them alters cognitive outcomes.