The Adult Cognitive Disease Wiki

Alzheimer's is not an event. It is a process in time.

The research corpus behind that idea — one hundred and fifty-nine long-form papers and six hundred and thirty-five linked concepts, arranged along the disease's own fifty-year timeline. You don't need to know where to begin: the four charts below are the whole argument in one sitting, and the papers sit underneath them.

The shape of the disease

Four charts · start here

Alzheimer’s is usually introduced as a list of things found in a brain after it has stopped working: plaques, tangles, shrinkage. A list has no shape. This corpus argues the disease does have one — that it happens in a particular order, over a particular stretch of a life, moving through particular places.

How to read these four charts

They are diagrams, not measurements. No one has watched a single brain lose its connections for sixty years, and these curves are not a record of anyone doing so. What they draw is the order and the shape this corpus argues for — which place is reached before which, what falls early, what falls late, and how far apart the two ends of that sequence sit. The heights are illustrative. The sequence is the claim, and it is a claim, not a settled fact: the evidence behind each step, and how firmly it is held, is in the papers these charts summarise.

1It begins long before anyone notices

The first thing lost is not a memory. It is a connection — one of the roughly hundred trillion junctions, called synapses, where a brain cell passes a signal to the next one. Losing them is not an event. It is a slow subtraction, and on this account it starts in early adulthood, in one small nucleus in the brainstem, and runs for decades in complete silence.

That silence is the single most important feature of the disease, and the reason it has been so hard to treat. By the time a person is sitting in a clinic being asked to remember three words, the process being named that day has been running for something like forty years.

The long silence

Connections from the locus coeruleus — the earliest place affected — plotted against age.

The shaded stretch is the part of the disease no one sees. On this account, the earliest-affected connections are approaching half gone by the time a person turns 50, and the diagnosis arrives near the far end of the curve — not at its beginning.

2It travels a fixed route

The disease does not appear everywhere at once, and it does not appear at random. It starts in one place and moves along the wiring to the next, in an order that is much the same from brain to brain. That regularity is the reason it is possible to talk about a shape at all.

The route begins in the locus coeruleus — a speck of tissue in the brainstem, no bigger than a grain of rice, that supplies the whole cortex with noradrenaline and does the work of waking you and holding your attention. The second place reached is its counterpart, the nucleus basalis, which supplies acetylcholine. Both are small, ancient nuclei that send a single thin axon an enormous distance to keep the rest of the brain in a working state; both are, on this account, in trouble before the structures they serve.

Only then does the disease appear in the places that produce the symptoms — the doorway into memory, memory itself, the amygdala — and last of all in the neocortex, the thinking surface, where the losses everyone recognises finally show up.

A fixed route through the brain

The age at which each place has lost about a quarter of its connections.

Read top to bottom, this is the order — locus coeruleus, nucleus basalis, entorhinal cortex, hippocampus, amygdala, neocortex. Read left to right, it is the timetable: roughly 22 years separate the first station from the last, which is why changes in sleep, mood and arousal can precede a memory complaint by decades and be dismissed as ordinary ageing. The rows are sorted by the curves themselves, not by assertion.

3Every place keeps its own clock

Put those six places side by side and the disease stops looking like a switch and starts looking like a wave. Each panel below is one place, drawn against the other five in grey. The curve moves rightward down the sequence: the brainstem is already well down its slope while the neocortex has barely started.

This is what is meant by the disease having a shape in time and space at once. There is no single moment at which someone “gets” Alzheimer’s, and no single place where it lives. There is a front, and it moves.

The wave, place by place

The same measure, the same axes, six times over.

Grey lines are the other five places, repeated in every panel so each can be read against the whole set. The coloured line is the panel’s own.

4And inside each place, it is selective

Zoom into a single region and a fourth dimension appears. The disease does not thin out a piece of cortex evenly, like paint fading. It takes specific connections from specific kinds of cell, and leaves others comparatively alone — for a while.

The clearest case is the PV interneuron, a cell whose job is timing: it inhibits its neighbours in fast, precise rhythm and keeps cortical activity from running away with itself. It is wrapped in a protective mesh called a perineuronal net, and for six decades it is the best-protected cell on the chart. Then the mesh is digested, and it becomes the worst-affected one.

Not every cell falls together

The neocortex, broken out by the kind of cell losing its connections.

For most of a life the PV interneuron loses less than anything around it. The crossing point, late on, is the moment its protection fails — and it is the argument for why the last phase of the disease arrives so much faster than the first.

Why the shape matters

If this account is right, then most of what makes a person recognisably ill happens at the far right of these charts — and almost every drug ever trialled has been given there, in the last few years of a forty-year process. The shape suggests the target is further left.

It also carries a genuinely hopeful implication. What these charts plot is connections, not cells. A silenced neuron that has lost its inputs is in a different condition from a dead one, and this corpus argues that a good deal of what is lost in the late phase is the former — cells that have stopped speaking rather than cells that have gone. Whether that is recoverable is an open question, and one of the most consequential in the field.

The full argument, with the evidence for each step and a grade on how firmly it is held, is in The Temporal Architecture of Collapse. To move through the same material yourself, the interactive Temporal Chart lets you pick any place and take the phases apart.

The lead paper · read this first

The Temporal Architecture of Collapse

One paper frames everything else here. It lays out the three-phase, fifty-year course each other document elaborates: the brainstem eroding decades before symptoms, the mid-life inflammatory turn, and the visible synaptic collapse at the end. Read it once and the rest of the wiki has a shape.

Read the paper →

The fifty-year front · in order

iGroundworkThe substrate beneath every phase32 iiPhase I · age 20–50The locus coeruleus dims21 iiiPhase II · age 50–70The microglial & matrix turn23 ivPhase III · age 70+The synapse fails, visibly25 vConvergence & SynthesisWhere the independent lines meet37

Beyond the map · a candidate for what comes first

The Fifty-Year Prescription

The temporal architecture says in what order the disease happens. It does not say why it begins. This paper is the most developed attempt here at the second question, and it is offered as a plausible account of priority rather than a settled one — a single mechanism followed without a break from a lifelong drift in the ecology of the gut, through the vagal relay and the locus coeruleus, to the withdrawal of a serotonergic tone that had been holding amyloid production down for decades before the first plaque, and on to the antidepressant trials that engage the right target half a century late.

It is a chain, and a chain of thirteen plausible links is not a plausible chain — so every claim is graded where it is used, and the paper closes with forty-one graded claims, eleven predictions, and the specific result that would break each link. The most upstream link, that gut ecology is a cause and not a companion, is the least established, and says so.

Read the paper →

One lesion, a century apart

1907 — today

The oldest idea in this corpus and one of its newest are the same idea. In 1907 Oskar Fischer read the plaque as a process — a lesion growing outward from a dying neuron. A century later two prize entrants re-derived his morphogenesis in molecular terms: amyloid accumulates inside the neuron, and the plaque is the gravestone of a cell killed from within.

1907 · the founder Oskar Fischer The prize's namesake read the plaque as a morphogenetic event with a developmental history. the inside-out plaque Fischer → Gouras → Nixon Amyloid builds inside the neuron years before any plaque; the deposit is a tombstone, not a cause. where it converges The endosomal nexus Retromer failure, lipid peroxidation and autophagic collapse all land in one compartment.

Every stage, in order

All documents →

The full reading sequence — the molecular groundwork, the three clinical phases, then the spread, convergence, synthesis and frontier.

1The Record — Fischer, 1907, and how the field went wrong→ 2Groundwork — the substrate beneath every phase→ 3Phase I — age 20–50, the locus coeruleus, decades before symptoms→ 4Phase II — age 50–70, microglia, the inflammasome, and the matrix→ 5Phase III — age 70+, where the disease finally becomes visible→ 6The Convergence — autophagic collapse and its upstream triggers→ 7The Synthesis — the cross-axis architecture→ 8The Frontier — therapeutics, experiments, and open questions→

The same argument, told at length

Everything above is the evidence — papers, concepts, the apparatus for reading them. The seven monographs are the argument those papers add up to, written as continuous narrative and meant to be read in order.

Groundwork First principles of collapse Every phase of collapse presupposes a substrate: the rule by which a neuron earns the right to stay connected, the ion that carries the signal and the bill, and the organelle that pays it. 4 chapters → Phase I· Age 20–50 Convergent bioenergetic collapse Tau pathology in Alzheimer’s does not begin in the cortex. 2 chapters → Phase II· Age 50–70 Convergent microglial collapse For a century, the microglial biology of Alzheimer's disease has been split between two mature, incompatible accounts: an "attack" framework in which microglia drive neurodegeneration through complement-mediated pruning and matrix digestion, and a "failure" framework in which dystrophic, exhausted microglia abandon the neurons they are meant to protect. 5 chapters → Phase III· Age 70+ Convergent synaptic collapse Phase III is the symptomatic phase — the failure of working memory, of cortical binding, of person and place. 5 chapters → The Crisis Convergent autophagic collapse For over a century, the field of neurodegeneration research has been defined as much by its divisions as by its discoveries. 4 chapters → The Spread Convergent propagation collapse For a century, the field has asked what kills the neuron. 5 chapters → Synthesis Convergent unified collapse The Synaptic, Microglial, and Perineuronal Net theses each performed an act of synthesis on its constituent research programs. 6 chapters → All seven, from the cover → Plus the Library, the Virtual Lab and the interactive views.

Or find your own way in

by concept635 recurring ideasEach concept lists every paper that leans on it. by convergenceThe 7 nodesWhere independent arguments land on one mechanism. by geneThe 205 genes namedLook a gene up by symbol and jump to its papers. the mapThe whole network, drawnEvery paper and concept at once, nodes as hubs. the matrixPhase × lens — every cell a cardThree phases crossed with eight lenses. the censusThe cellular front of failureScrub the disease through its five stations.

A note on this edition

This wiki publishes the science: the papers, the concepts, the convergence nodes and the temporal stages. It withholds the working dossiers on individual researchers, which are graded internal notes — where the text names one, it appears as plain text rather than a link.