Alzheimer's threshold levers — the cholinergic / glutamatergic / network symptomatic operating-point correction, decomposed into DNA-grounded levers (L3-dominant with L1+L2 engaged and a split corrective sign; the neurodegenerative-progression core named, out of reach — the third and deepest PARTIAL fit in the series)

Alzheimer's maps onto the threshold frame as the third and deepest partial fit. The reachable surface is purely symptomatic with a split sign: cholinergic drive restored, glutamate excitotoxicity reduced, inhibition restored. The dominant neurodegenerative-progression axis is an irreversible decay, named but out of reach. Symptomatic levers do not slow progression; a person with dementia remains a person.

The cholinergic-deficit, glutamatergic-excitotoxicity and network-hyperexcitability accounts of Alzheimer's each describe a real, treatable symptomatic surface — a deficient acetylcholine tone, an excess of excitotoxic NMDA drive, and a hyperexcitable cortical network — but every one of them sits on top of a single dominant fault that none of them resolves: neurodegenerative progression, the cumulative, irreversible loss of synapses and neurons that is the disease. That progression is the discriminant — it is what makes Alzheimer's Alzheimer's, and it is a degeneration, not a set-point. This chapter applies the same piece of inherited technology the bipolar, epilepsy, depression, schizophrenia, autism, ADHD and addiction levers chapters used — the threshold-shift intervention logic from the analgesic reproducibility package (Zenodo 10.5281/zenodo.20733420), whose three abstract levers are L1 change the inward (excitatory) current, L2 change the outward (potassium / inhibitory) current, L3 change the up-stream drive — and it produces the third and deepest PARTIAL fit in the series. Alzheimer's is the eighth distribution pattern, and the first whose reachable surface is both purely symptomatic and split-sign. Of nine lever genes, four sit on the up-stream cholinergic-drive lever (L3, restored: ACHE and BCHE the cholinesterases, CHRNA7 the α7 nicotinic subunit, CHRM1 the M₁ muscarinic receptor), two on the inward glutamate-excitotoxicity lever (L1, reduced: GRIN2B and GRIN2A), and three on the inhibitory-restore lever (L2, restored: GABRA1, GABRA5, GABRB3). The corrective sign is split: cholinergic drive is pushed up (restore a deficit), excitotoxic glutamate drive is pushed down (reduce an excess), inhibitory tone is pushed up (restore against network hyperexcitability) — the donepezil / rivastigmine / galantamine direction, the memantine direction, and an inhibitory-restore direction, all as directions, never doses. That engagement of L1 and L2 makes the reachable surface broad — broader than ADHD's, like addiction's — yet the fit is the deepest partial fit yet, for a precise reason. The reachable surface is purely symptomatic: these levers act on the instantaneous operating point, and they do not slow neurodegeneration. The dominant Alzheimer's fault is the PROG neurodegenerative-progression axis — the cumulative degeneration that drives the disease — and it is out of reach for the deepest reason in the series, a reason that compounds both prior partial fits and adds a third. It is a gain/loss, not a fold (the ADHD lesson: a lever that moves a fold has no handle on an amplitude). It is a progression over time — a plasticity (E0-layer) variable, not an instantaneous operating point (the addiction lesson). And it is, beyond both, a degeneration — a cumulative, irreversible loss, an E0 decay that is the structural inverse of addiction's E0 gain: addiction consolidates a trace the levers cannot erase, Alzheimer's loses a substrate the levers cannot rebuild. So even a drive lever that perfectly restores instantaneous cholinergic tone cannot halt the cumulative loss. The PROG axis is named with six real genes — APP the amyloid source, PSEN1 and PSEN2 the γ-secretase subunits, MAPT tau, APOE the strongest common risk allele, and TREM2 the microglial receptor — carried with their own promoter reads alongside but not reached. So the fit is graded [L] partial, the third and deepest non-clean fit in the series. Each gene is placed by reading its own promoter switch stiffness — γ = −mean nearest-neighbour stacking free energy (SantaLucia 1998) over its promoter window, turned into |h_sp| = spinodal(γ) with the frozen engine read-only — and five of the fifteen reads (GRIN2A, GRIN2B, GABRA5, GABRB3 from the autism cache, GABRA1 from the epilepsy cache) are carried over verbatim, with the ten cholinergic and progression genes live GRCh38 strand-aware reads. The DNA reads carry a decoupling that is orthogonal to reach, as addiction's was: the three stiffest promoters in the set are all reachable cholinergic levers (CHRM1, ACHE, CHRNA7), the two softest are also reachable levers (BCHE, GABRA1), and the six out-of-reach progression genes cluster in the middle of the stiffness range — so promoter stiffness predicts neither which axis a gene is on nor whether it can be reached. Two fail-closed disciplines ride along, and the forbidden-claim scanner adds two classes specific to this topic: a cure / reversal class (it rejects reverse / cure / prevent / halt-the-progression / restore-lost-memory / regrow-neurons / miracle-cure framing) and a dignity class (it rejects empty-shell / no-longer-a-person / vegetable / already-gone / not-worth-treating framing), both negation-guarded. The firewall is absolute: the promoter |h_sp| is a gene's own switch stiffness, never a neurodegeneration rate, an amyloid burden, a tau load, a receptor occupancy, a drug's potency, a dose, or a clinical effect. efficacy = 0; not medical advice; the cholinesterase-inhibitor and memantine directions are symptomatic only and do not slow progression; the anti-amyloid antibodies act on the out-of-reach progression axis; a person living with dementia remains a person; the hard problem stays open.

What the cholinergic, glutamate and network accounts establish (a degeneration, not a set-point)

Alzheimer's has been read for half a century through three mechanistic accounts, and each one identifies a real, treatable piece of the disorder. The cholinergic-deficit account (Davies and Maloney, 1976) observed that the basal-forebrain cholinergic neurons degenerate early and that acetylcholine signalling falls with cognitive decline — the rationale for the cholinesterase inhibitors that remain a mainstay of symptomatic care. The glutamatergic-excitotoxicity account observed that tonic over-activation of NMDA receptors contributes to the synaptic and neuronal damage of advancing disease — the rationale for memantine, a low-affinity, use-dependent NMDA channel blocker. And the network-hyperexcitability account (Palop and Mucke, 2007; Vossel and colleagues) observed that Alzheimer's cortex is prone to subclinical epileptiform activity, that this hyperexcitability worsens cognition, and that restoring inhibitory tone is a coherent target. Three accounts, three surfaces — a deficient drive, an excess current, a hyperexcitable network — and all three are surfaces a threshold lever could, in principle, move.

But all three accounts share a feature that this chapter is built around: they are symptomatic. Each describes a part of the operating point that can be nudged toward normal now, and none of them touches the dominant fault that sits underneath. That fault is neurodegenerative progression — the cumulative, irreversible loss of synapses and neurons, driven by amyloid-β accumulation, tau spread, impaired clearance and microglial dysfunction — and it is a different kind of variable from any set-point. It does not oscillate, switch, or sit at a level a lever can shift; it accumulates, in one direction, and what it removes does not come back. Alzheimer's is, before it is anything else, a degeneration. The cholinergic, glutamate and network accounts tell us where the symptomatic surface is; they are silent on whether the progression can be reached at all. That silence is exactly the question the threshold frame is about to make precise — and, as with ADHD and addiction, the honest answer is that the frame catches the symptomatic surface and cannot reach the dominant axis.

The inherited technology, applied an eighth time — the L3-dominant, split-sign, symptomatic pattern

The handle is not invented here. It is the same threshold-shift intervention logic the bipolar, epilepsy, depression, schizophrenia, autism, ADHD and addiction chapters inherited from the analgesic reproducibility package (Zenodo 10.5281/zenodo.20733420). Its premise is general: an operating point is set by a balance of currents and the drives that bias them, so there are exactly three levers on it. L1 — change the inward, excitatory current. L2 — change the outward, repolarising (or inhibitory) current. L3 — change the up-stream drive that sets where the operating point sits. The frame applies unchanged because the Alzheimer's symptomatic substrate, the seven prior levers chapters, and the analgesic package all share the same R19 substrate — the engine's supercritical pitchfork ṣ = g·s − s³ + h, whose spinodal fold IS the switching barrier. Nothing about the engine is touched; the module re-emerges the frozen tree read-only, confirms it byte-unchanged, and registers as the sixteenth atlas citizen (AD-T3b-L).

Alzheimer's is the eighth distribution pattern across the series, and its reachable surface has a property none of the others did: it is both purely symptomatic and split-sign. Of nine lever genes, four sit on L3 (the up-stream cholinergic drive), two on L1 (the glutamate-excitotoxicity current), and three on L2 (the inhibitory-restore axis) — gross shape kin to addiction's L3-dominant-with-L1/L2 engagement, but with a corrective sign that is not uniform. On L3 the direction is restore: cholinergic tone is deficient, so the lever pushes it up (the donepezil / rivastigmine / galantamine direction). On L1 the direction is reduce: excitotoxic NMDA drive is excessive, so the lever pushes it down (the memantine direction). On L2 the direction is restore: inhibitory tone is deficient against a hyperexcitable network, so the lever pushes it up. A lever map that pushes one current up, another down, and a third up — a split corrective sign on a single disorder — is new to the series, and it is the structural signature of a disorder whose symptomatic surface is a balance gone wrong in several directions at once, not a single set-point displaced one way. The pipeline is reused at the level of code, not analogy: five of the fifteen reads — the NMDA subunits GRIN2A and GRIN2B and the GABA_A subunits GABRA5 and GABRB3 from the autism cache, and GABRA1 from the epilepsy cache — are carried over verbatim, because γ is a strand-symmetric property of the sequence and does not change between problems; the ten cholinergic and progression genes (ACHE, BCHE, CHRNA7, CHRM1, APP, PSEN1, PSEN2, MAPT, APOE, TREM2) are fetched fresh (GRCh38, strand-aware).

The third and deepest partial fit: why the dominant axis is out of reach for the deepest reason

This is the result that makes Alzheimer's the most structurally honest chapter in the series, and the third that does not produce a clean fit. The module says so in a partial-fit witness that grades the fit [L] partial, records it as the third partial fit, and marks it the deepest. The reachable side is genuine and broad: the lever frame reaches the instantaneous symptomatic operating point across all three levers — the L3 cholinergic drive, the L1 glutamate-excitotoxicity current, and the L2 inhibitory restore — exactly where the established symptomatic pharmacology acts. But the dominant Alzheimer's fault is neurodegenerative progression, and it sits out of reach for a reason that compounds both prior partial fits and adds a third on top. The first sense is the ADHD lesson, inherited intact: progression is a gain/loss, not a fold — an instantaneous lever moves an operating point, and no operating-point shift sets the amplitude of a cumulative process. The second sense is the addiction lesson: progression is a process over time, a quantity that accrues through the plasticity (E0) layer rather than an instantaneous operating point a lever can shift at all. ADHD's gain was at least instantaneous; addiction's gain was a learned trace; Alzheimer's progression is a process that runs.

The third sense is new, and it is what makes Alzheimer's the deepest partial fit. Progression is not merely a gain, and not merely a learned accrual — it is a degeneration: a cumulative, irreversible loss of synapses and neurons. This is an E0 decay, and it is the structural inverse of addiction's E0 gain. Addiction consolidates a trace into the connectome — the plasticity layer writes something the instantaneous levers cannot erase. Alzheimer's removes substrate from the connectome — the degeneration deletes something the instantaneous levers cannot rebuild. The two disorders meet the same E0 plasticity layer from opposite directions: one as accumulation, one as loss. And loss is, if anything, further out of reach of a threshold lever than gain, because a lever restores a tone, and no tone-restoration regrows a neuron that is gone. So a drive lever that perfectly restores instantaneous cholinergic signalling still leaves the cumulative loss untouched — which is precisely why the cholinesterase and memantine directions are symptomatic only and do not slow progression. The partial grade is the finding, not a failure: it marks exactly where the cross-cutting threshold logic does and does not apply, and it refuses to manufacture a clean fit on a biology whose core is an irreversible degeneration rather than a threshold. The module captures all of this in a domain-restriction witness (SYMP = reached across L1/L2/L3 with a split sign, PROG = named but not reached) and an out-of-reach-targets section that lists the six progression genes by name — making the partiality concrete, axis-structured and gene-named rather than a vague hedge.

L3 is the core — four cholinergic-drive levers, restored (the symptomatic mainstay as directions)

The largest reachable lever is the up-stream cholinergic drive, and it carries four genes — the enzymes and receptors that set the tone of acetylcholine signalling, the surface the symptomatic mainstay of Alzheimer's care has always acted on. ACHE is acetylcholinesterase, the enzyme that hydrolyses acetylcholine in the synapse and the molecular target of the donepezil / rivastigmine / galantamine direction — inhibiting it raises synaptic acetylcholine, the canonical restore-a-deficit move. BCHE is butyrylcholinesterase, the second cholinesterase whose relative role rises as acetylcholinesterase falls in advancing disease, and the co-target of dual-inhibitor rivastigmine. CHRNA7 is the α7 nicotinic acetylcholine receptor, a pre- and post-synaptic cholinergic node, and CHRM1 is the M₁ muscarinic acetylcholine receptor, the principal post-synaptic muscarinic node — both are receptor-level directions on the same cholinergic drive. On all four the corrective sign is restore: cholinergic tone is deficient in Alzheimer's, so the lever pushes it up. These map the real-world symptomatic pharmacology onto the cholinergic-drive lever as directions on a lever, never as doses, drugs, or recommendations.

The crucial discipline is the one the whole frame turns on: a promoter read places a gene on a lever; it says nothing about whether raising or lowering that gene's activity is the therapeutic direction, or how far is too far, or in whom. Every one of the four cholinergic-drive links is graded [O] cited biology, never derived from the substrate. And the cholinergic levers carry the central honesty of this chapter built in: a drive-tone lever modulates the instantaneous tone of cholinergic signalling, which is a real and reachable handle that can relieve symptoms, but it does not reach down into the neurodegeneration that is removing the cholinergic neurons in the first place. Restoring acetylcholine in a circuit that is losing its neurons is, structurally, holding a level steady while the substrate erodes — genuine symptomatic benefit, no effect on the loss. So the cholinergic levers are real, actionable directions on the reachable symptomatic axis, and they are explicitly not a claim to have reached the progression. A direction, never a dose; the agents are named as a sign on a lever, never as something to obtain or titrate, and they do not slow the disease. efficacy = 0.

L1 and L2 engaged — glutamate excitotoxicity reduced, inhibitory tone restored (the split sign)

What gives Alzheimer's its split corrective sign is that the ionic levers pull in opposite directions. The inward lever L1 carries two glutamate genes, and here the direction is reduce. GRIN2B and GRIN2A are the NMDA-receptor 2B and 2A subunits — the glutamatergic machinery whose tonic over-activation contributes to excitotoxic synaptic and neuronal damage in advancing disease, and the substrate where the memantine direction acts by dampening that excess drive (preferentially through the 2B subunit). Because the fault on this lever is an excess, the corrective push is downward — the opposite of the cholinergic levers' upward restore. The outward lever L2 carries three GABA genes, and here the direction is restore again. GABRA1, GABRA5 and GABRB3 are GABA_A-receptor subunits — the inhibitory machinery whose restoration counters the network hyperexcitability (the subclinical epileptiform activity) that is common in Alzheimer's and worsens cognition; GABRA5 in particular carries the extrasynaptic tonic-inhibition role. So Alzheimer's engages all three lever classes on its reachable symptomatic surface, with a sign that splits: drive up (L3), excitotoxicity down (L1), inhibition up (L2).

That split is the structural fingerprint of the disorder's symptomatic surface, and it is worth stating plainly what it means and what it does not. It means the reachable surface is a multi-directional rebalancing — a deficient drive to lift, an excess current to damp, a lost inhibition to restore — rather than a single set-point displaced one way, which is why a single ‘more’ or ‘less’ never described Alzheimer's symptomatic care and why three different drug rationales coexist. It does not mean the fit is any less partial: a broader, multi-directional reachable surface still does not touch the dominant fault, because that fault is not on any of the three instantaneous levers at all. Like addiction, Alzheimer's recruits L1 and L2 — its actionable symptomatic biology is broad; unlike any prior chapter, it recruits them with opposite signs. Each of the five ionic links is graded [O] cited biology, never derived; the glutamate-reduce and GABA-restore directions are genuine handles on the instantaneous network excitability, and they are explicitly not a handle on the progression. Engaging L1 and L2 widens what the frame reaches and splits the sign; it does not let the frame reach the degeneration.

The out-of-reach PROG axis: amyloid, the presenilins, tau, APOE, TREM2 — an E0 decay

The dominant Alzheimer's fault is the PROG neurodegenerative-progression axis — the cumulative, irreversible loss that drives the disease — and it is exactly the axis the instantaneous levers cannot reach. The module names it with six real genes, each carried with its own promoter read alongside but explicitly not a lever. APP is the amyloid precursor protein, the source of the amyloid-β peptide and an autosomal-dominant early-onset familial-Alzheimer's gene. PSEN1 and PSEN2 are the presenilins, the catalytic subunits of the γ-secretase that cleaves APP and the commonest early-onset familial genes. MAPT is tau, whose neurofibrillary tangles track the severity and spread of the disease. APOE is apolipoprotein E, whose ε4 allele is the strongest common genetic risk factor for late-onset Alzheimer's, acting on amyloid clearance and lipid handling. And TREM2 is the microglial receptor whose rare variants impair the microglial response to amyloid and degeneration. Together these six are the progression: the amyloid / γ-secretase, tau, clearance and microglial machinery whose cumulative action is the neurodegeneration.

None of these is a lever, and the reason is the tripled one from the partial-fit section: progression is a gain/loss, not a fold (no instantaneous lever sets the amplitude of a cumulative process), it is a process over time (it accrues through the plasticity layer, not an instantaneous operating point), and it is a degeneration — an E0 decay, a cumulative irreversible loss that is the structural inverse of addiction's E0 gain. This is the precise point the chapter builds toward: addiction's out-of-reach axis was the E0 plasticity layer met as accumulation; Alzheimer's out-of-reach axis is the same E0 layer met as loss. A lever restores a tone; it does not regrow a neuron that the degeneration has removed, just as it could not erase a trace the plasticity had written. So the honest move — and the one this chapter makes — is for the threshold frame to name the progression out of reach rather than pretend a drive or ionic lever can halt a degeneration. It is worth being exact about the real therapeutics here: the anti-amyloid antibodies (lecanemab, donanemab) do act on this PROG axis — they are progression-modifiers, not threshold levers, and they only modestly reduce the rate of clinical decline, with serious caveats. They belong to the dynamics of the out-of-reach axis, not to the symptomatic lever surface this chapter reaches. Each of the six genes is graded [F] NOT REACHED for the lever frame (axis-structured, not dose-structured), with its promoter γ read carried alongside as [V] structural context only.

The DNA grounding: a promoter's own switch stiffness, and a decoupling orthogonal to reach

What places each of the fifteen genes — the four cholinergic levers, the two glutamate levers, the three GABA levers, and the six out-of-reach progression genes — is not a list but a read. For every gene, the module takes its promoter window (transcription start −2000 to +500 bases, Homo sapiens) and computes γ = −mean of the nearest-neighbour base-stacking free energies along that window (the SantaLucia 1998 nearest-neighbour thermodynamics), then turns that γ into the promoter's switch stiffness through the frozen engine's own functions: |h_sp| = spinodal(γ) = 2(γ/3)^1.5 and barrier = γ²/4. The reads span a real range. The four cholinergic levers, stiffest to softest, are the M₁ muscarinic receptor CHRM1 at γ ≈ 1.513 (|h_sp| ≈ 0.716, the stiffest in the whole set), acetylcholinesterase ACHE (γ ≈ 1.510, |h_sp| ≈ 0.714), the α7 nicotinic subunit CHRNA7 (γ ≈ 1.496, |h_sp| ≈ 0.704), and butyrylcholinesterase BCHE (γ ≈ 1.233, |h_sp| ≈ 0.527, the softest in the whole set). The two L1 glutamate levers read GRIN2A at γ ≈ 1.470 (|h_sp| ≈ 0.686) and GRIN2B (γ ≈ 1.361, |h_sp| ≈ 0.611); the three L2 GABA levers read GABRB3 at γ ≈ 1.409 (|h_sp| ≈ 0.644), GABRA5 (γ ≈ 1.372, |h_sp| ≈ 0.619) and GABRA1 (γ ≈ 1.246, |h_sp| ≈ 0.536). And the six out-of-reach progression genes read in the middle of the range: APOE at γ ≈ 1.480 (|h_sp| ≈ 0.693), MAPT (γ ≈ 1.476, |h_sp| ≈ 0.690), APP (γ ≈ 1.447, |h_sp| ≈ 0.670), PSEN2 (γ ≈ 1.427, |h_sp| ≈ 0.656), PSEN1 (γ ≈ 1.398, |h_sp| ≈ 0.636), and TREM2 (γ ≈ 1.377, |h_sp| ≈ 0.622).

That range tells a story, and it is the same orthogonality addiction showed, even more cleanly. Stiffness is orthogonal to reach: the three stiffest promoters in the entire set — CHRM1, ACHE, CHRNA7 — are all reachable cholinergic levers, and the two softest — BCHE and GABRA1 — are also reachable levers, while the six out-of-reach progression genes cluster in the middle of the stiffness range (their |h_sp| values, ≈ 0.622–0.693, sit between the cholinergic extremes). Reachable genes occupy both ends of the stiffness range, and every out-of-reach gene sits in the interior — so promoter stiffness predicts neither which axis a gene is on nor whether it can be reached. That orthogonality is itself the cleanest demonstration of the firewall: if stiffness drove anything, this arrangement could not occur. These are read on the same R19 substrate, with the same engine, that the bipolar, epilepsy, depression, schizophrenia, autism, ADHD, addiction and analgesic packages used — one substrate, one pipeline, now eight problems. And the γ read is a property of the gene's promoter sequence, blind to whether the gene is on or off and to gain / loss / expression level — that is all it is, and it is the reason the next section's ranking can carry γ alongside every target without ever letting it touch the score.

Ranking targets, the Alzheimer's unmet-need signature, and the firewall that adds two guards

The last component prioritises, and it prioritises targets, never drugs or doses. The Alzheimer's ranking spans all fifteen genes (the nine levers and the six out-of-reach progression genes), precisely so the partiality is visible in the ranking itself. A burden-weighted score combines three declared, cited weights — clinical burden (0.40), unmet need (0.35), and genetic-evidence / druggability (0.25) — on cited 1–5 tiers. The Alzheimer's signature is the deepest-partial signature of all: the top of the ranking is non-actionable. The two highest-scoring targets are APP at #1 (score 4.75) and APOE at #2 (4.50) — both out-of-reach progression genes — because they carry the highest burden and the highest unmet need: disease modification is the single greatest unmet need in the field, and nothing selectively reaches the degeneration. They are flagged not actionable, because ranking a target you have already declared out of reach as a next step would be incoherent. The leading actionable target is acetylcholinesterase ACHE at #3 (4.30) — the donepezil / rivastigmine direction — the highest-ranked gene the lever frame can actually move. Alzheimer's unmet-need floor is set at 3, above ADHD's floor of 2, because the reachable routes are only symptomatic and temporary — they relieve symptoms but do not slow the disease, so unmet need stays elevated even where a lever exists.

The consequence is a ranking that itself encodes the deepest partial fit: the highest-burden, highest-unmet targets are the out-of-reach progression genes, and the leading actionable target sits below them. Where the unmet need is highest the target is unreachable (the degeneration), and where the target is reachable the benefit is only symptomatic (no effect on progression) — the signature of a disorder whose treatments relieve the surface while the dominant axis runs untouched. This also produces the firewall made visible, as decoupling. The γ read is carried alongside each target as structural context but is never folded into the score: the stiffest promoter in the set, the M₁ muscarinic receptor CHRM1 (|h_sp| ≈ 0.716), sits at priority #6, not the top; and the top-priority target, the amyloid source APP, has only the seventh-stiffest read. If promoter stiffness drove the ranking, neither target could sit where it does.

A fail-closed forbidden-claim scanner guards the whole package, and for Alzheimer's it adds two classes specific to dementia. The cure / reversal class rejects reverse, cure, prevent, halt-the-progression, restore-lost-memory, regrow-neurons and miracle-cure framing outright, because the reachable surface is symptomatic only and none of it slows, stops, or reverses the disease — the gravest YMYL risk around Alzheimer's is exactly the cure-and-reversal myth that preys on patients and families. The dignity class rejects empty-shell, no-longer-a-person, vegetable, already-gone and not-worth-treating framing, because a person living with dementia remains a person. Both classes are negation-guarded — a sentence that rejects a frame (‘does not slow the disease’, ‘is not a cure’, ‘is not an empty shell’) is allowed, a sentence that asserts one fails the build — and each carries a planted self-test that must fire on its own bait, failing the build if it ever does not. The firewall must be stated once more in full: the promoter |h_sp| is a gene's own switch stiffness, and it is never equated with a neurodegeneration rate, an amyloid burden, a tau load, a receptor occupancy, a drug's potency, a dose, an in-vivo selectivity, or any clinical effect. This module reproduces bit-for-bit with the engine byte-unchanged.

Discipline: symptomatic only, never disease-modifying — a person with dementia remains a person

Everything here is an in-silico reading of promoter sequence and a frame for organising targets, not a clinical measure, a diagnosis, or a prescription. The model asserts mechanism directions and target placements — Alzheimer's symptomatic surface can be engaged through the up-stream cholinergic-drive lever and, like addiction, through the ionic levers too, with a split sign; these cholinergic, glutamate and GABA genes populate those levers; Alzheimer's loads most on L3 but engages L1 and L2; the map reaches the instantaneous symptomatic operating point across all three levers; the dominant neurodegenerative-progression axis is named and out of reach — for the deepest reason in the series, as a gain/loss, a process over time, and a degeneration (an E0 decay, the inverse of addiction's gain); the fit is therefore the third and deepest [L] partial fit — and nothing about which agent acts on any lever, at what dose, in whom, whether any real compound changes anyone's condition, or that anyone should change anything. The agents named as directions (the donepezil, rivastigmine, galantamine and memantine arms) are illustrations of a sign on a reachable lever, never a recommendation, and the recorded structure — the dominant axis out of reach, the progression named but unreached — is there precisely because a generic lever placement is not a clinical direction. Real Alzheimer's is polygenic and heterogeneous, and its established symptomatic pharmacology is only temporarily and modestly effective and does not slow the disease — a limit that is locked, not smoothed over.

Two stricter boundaries close the chapter. First, the reachable levers are symptomatic only. The cholinesterase-inhibitor and memantine directions act on the instantaneous operating point; they can relieve symptoms, and they do not slow, stop, or reverse neurodegeneration. The map does not assert that any lever direction is disease-modifying, and the only therapeutics that touch the progression at all — the anti-amyloid antibodies — act on the out-of-reach axis, are progression-modifiers rather than threshold levers, and only modestly reduce the rate of clinical decline. Second, a person living with dementia remains a person. The dignity class in the scanner is not decoration: Alzheimer's is surrounded by dehumanising language, and this chapter rejects all of it — the disorder is a degeneration of a substrate, not a subtraction of a person, and nothing in the mechanism described here licenses treating anyone as an empty shell or a lost cause. A promoter read and a lever assignment are mechanism boundaries, not a claim about the felt quality of memory, loss, or selfhood in dementia (Axis-A firewall — consciousness_claim = 0, the hard problem stays open). This is not medical advice, not a diagnosis, not a treatment protocol, and not a cure. medium_efficacy_tested = 0; targets ranked, never drugs or doses; no cure, reversal, prevention, or dignity-violating framing; the reachable levers are symptomatic only and do not slow progression; a person living with dementia remains a person.