We apply the Identity Axis Framework to Alzheimer's disease, identifying it as the first framework entry with two simultaneous and mechanistically distinct identity drift events operating at two different organisational levels. Drift Event 1 (Cellular): Cortical and hippocampal neurons lose their committed neuronal identity. Identity Anchor: MEF2C / NEUROD2. Convergence Hub: DYRK1A. DYRK1A phosphorylates and inactivates MEF2C (Identity Anchor suppression), simultaneously phosphorylates tau (accelerating aggregation), and promotes aberrant cell cycle re-entry. REST, which normally acts as an epigenetic guardian of the correct neuronal attractor, is sequestered in autophagosomes by tau aggregates, removing the checkpoint. The identity axis ratio is RAD = MEF2C / DYRK1A. The drug target is a CNS-penetrant DYRK1A inhibitor (Leucettine L41, GNF2133 — both in or near clinical trials). Drift Event 2 (Memory): Engram cells lose their memory identity — the specific synaptic and epigenetic signature (H3K27ac at Arc, Fos, BDNF, GluR1/2 loci) that encodes a particular memory. Identity Anchor: CREB/BDNF/TrkB. Hub: HDAC2/HDAC3 over-activity. The memory is not erased but inaccessible: the informational structure has drifted below retrieval threshold. Drug target: selective HDAC2 inhibitor + TrkB agonism + CREB activation (PDE4 inhibitor). The Information Preservation Hypothesis: memories that appear lost in early AD are inaccessible, not erased; HDAC2 inhibition may restore access. Confirmed experimentally by Roy et al. 2016 (Nature) optogenetic engram reactivation in APP/PS1 mice. We derive: the geometric subtype structure (cognitive reserve as high RAD) ; the Down syndrome / DYRK1A connection (chromosome 21 trisomy = constitutive DYRK1A overexpression = early threshold crossing = AD onset by age 40) ; the amyloid repositioning (upstream Hub activator, not the Hub itself; explains why lecanemab slows but does not halt) ; the REST inversion geometry (REST is protective in aging, not the Hub — REST loss is downstream of DYRK1A via tau sequestration). Eight falsifiable predictions are stated, all timestamped 2026-03-09.
Eric Robert Lawson (Mon,) studied this question.