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A Deterministic Framework for Neuroimmune Energetic Allocation via Epigenetic Hysteresis

This paper proposes the Host Energetic Allocation Model (HEAM), a deterministic biophysical framework demonstrating that epigenetic hysteresis traps myeloid cells in a high-metabolic state after viral clearance, thereby causing chronic neural energy depletion and explaining the pathophysiology of post-acute infection syndromes like Long COVID.

Original authors: Teerach Dhebhasit

Published 2026-07-10

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CC BY 4.0

Original authors: Teerach Dhebhasit

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ⚕️ This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer

Imagine your body is a bustling city with a strict energy budget. You only have a fixed amount of "fuel" (glucose) circulating in your bloodstream at any given time—about 4 grams of freely available fuel. In this city, the brain is the VIP district. It's the "Selfish Brain," hogging a massive 20% of that fuel just to keep the lights on and the neurons firing, even when you're just sitting still.

Usually, this system works like a spring. If an invader (like a virus) shows up, the immune system's "construction crew" (your myeloid cells) rushes in. They switch their engines to a high-octane, fuel-guzzling mode to fight the bad guys. Once the virus is defeated, the crew packs up, the fuel demand drops, and the brain gets its 20% back. The city returns to normal.

But here is the twist proposed in this new study: What if the crew doesn't pack up?

The "Ghost" in the Machine
The author, Teerach Dhebhasit, suggests that for some people, the fight leaves a permanent "scar" on the construction crew's instruction manual. Even after the virus is completely gone, the crew's DNA keeps them stuck in "high-alert" mode. This is called epigenetic hysteresis. Think of it like a sticky switch that got jammed in the "ON" position.

In this scenario, the immune cells keep acting like they are in the middle of a war, gobbling up glucose at a voracious rate. Because the city's total fuel budget is a strict zero-sum game (you can't create more fuel out of thin air), if the immune cells are stealing extra fuel, the brain must get less.

The Mathematical Trap
The paper uses a computer simulation called the Host Energetic Allocation Model (HEAM) to test this idea. It's not a study of real patients yet; it's a mathematical proof of concept.

The simulation shows that once the immune cells get "trained" by the virus to stay hungry, they get trapped in a topological loop. Even when the virus count drops to zero, the system refuses to snap back to normal. The immune cells lock into a "high metabolic attractor basin"—a fancy way of saying they are stuck in a deep valley of high energy demand that they can't climb out of.

The study ran this simulation 100 times with different virtual people, tweaking their body stats by ±10% or ±15%. In 100% of those simulations, the hosts failed to return to their baseline energy state, gliding instead into a permanent chronic metabolic tax corridor. The brain was permanently starved of its usual fuel share, leading to the "cognitive fatigue" and "brain fog" seen in Long COVID.

What This Is NOT
It is important to know what this paper doesn't say. It does not claim that the virus is still hiding in the body, eating up the fuel. The simulation explicitly shows the virus is gone (cleared by day 35 in the model), yet the fatigue remains. It also does not claim that the brain itself is damaged or inflamed. Instead, it suggests the brain is simply being out-competed for resources by a stubborn immune system that forgot how to turn off.

The Bottom Line
This is a theoretical framework, a "what-if" story told in the language of math and physics. It suggests that the exhaustion of Long COVID might not be a broken engine, but a traffic jam caused by a construction crew that never left the site. The model proves that if your immune cells stay "trained" to be hungry, the math forces your brain to go hungry, too.

The author notes that this is a simplified view—it assumes the body is a well-mixed soup and doesn't yet account for the complex traffic rules of the blood-brain barrier. But the simulation suggests that this "metabolic theft" is a robust, mathematically unavoidable consequence of how our immune memory works, offering a new way to understand why some people just can't seem to get their energy back.

Technical Summary: A Deterministic Framework for Neuroimmune Energetic Allocation via Epigenetic Hysteresis

Problem Statement
The paper addresses the persistent clinical phenomenon of Post-Acute Sequelae of SARS-CoV-2 (PASC), or Long COVID, characterized by debilitating cognitive fatigue, post-exertional malaise, and executive dysfunction. While epidemiological data confirms the scale of the crisis, the precise molecular etiology driving this systemic neuro-energetic collapse remains undefined. Existing hypotheses often rely on ongoing viral replication, localized neuro-invasion, or diffuse neuro-inflammation. The author identifies a critical gap in deterministic frameworks capable of explaining chronic fatigue in the absence of active viral reservoirs, specifically focusing on the energetic constraints of the neuro-immune axis under rigid thermodynamic limits.

Methodology
The study introduces the Host Energetic Allocation Model (HEAM), a theoretical biophysical framework utilizing a system of ordinary differential equations (ODEs) to simulate host energetic allocation over a 120-day horizon. The model operates under a strict zero-sum conservation law, positing that total circulating glucose is a fixed budget (approximately 4 grams at steady state) shared between the central nervous system (CNS), somatic/peripheral buffers, and the myeloid immune compartment.

Key components of the mathematical framework include:

State Variables: The model tracks circulating pathogen load ( $P$ ), persistent H3K27ac epigenetic marks in the myeloid compartment ( $M$ ), and systemic myeloid glucose demand ( $I$ ).
Epigenetic Dynamics: The accumulation of epigenetic memory ( $M$ ) is modeled via a Hill-type activation function reflecting ultrasensitive mTOR-dependent metabolic switching, opposed by zero-order decay kinetics representing chromatin scar resolution.
Energetic Constraints: The CNS is locked to an obligate 20% of resting metabolic rate for baseline function. As myeloid demand ( $I$ ) increases, neural allocation ( $N$ ) must mathematically decrease to satisfy the fixed substrate budget.
Simulation Techniques: The study employs phase space analysis to visualize attractor basins and bistable hysteresis orbits. Additionally, a Monte Carlo stochastic sensitivity analysis was conducted across a heterogeneous virtual cohort ( $N=100$ ) with structural and kinetic variances to test the robustness of the topological trap.

Key Results

Bistable Hysteresis: Phase space analysis reveals a severe bistable hysteresis orbit. While the system snaps into a high-metabolic state during acute infection (Warburg-like phenotype), the removal of the pathogen stimulus does not return the system to its original quiescent state. Instead, high-cooperativity switching locks the myeloid cells into an elevated "upper attractor basin."
Persistent Metabolic Tax: In the HEAM experimental cohort, the persistent epigenetic mark forces myeloid demand into a protracted plateau. This creates a "chronic systemic energy tax" where the myeloid compartment acts as a voracious glucose sink, mathematically mandating the prolonged down-regulation of neural substrate allocation.
Universal Conservation: The Monte Carlo simulations confirm that this topological trap is universally conserved. Despite significant physiological variation (±10% capacity, ±15% kinetic rates), 100% of simulated hosts failed to return to baseline homeostasis, gliding instead into a permanent chronic metabolic deficit corridor.
Analytical Proof: The derivation of the quasi-steady-state limit ( $I^*$ ) demonstrates that a return to baseline myeloid demand is strictly impossible as long as the epigenetic memory scar ( $M$ ) persists, thereby enforcing a state of cognitive substrate deprivation.

Significance and Claims
The paper claims to provide a purely theoretical biophysical mechanism for the macroscopic clinical phenomenology of PASC, independent of persistent viral reservoirs. The primary significance lies in reframing Long COVID not as a result of ongoing neural injury, but as the "mathematical inevitability" of a chronic, pathogen-induced thermodynamic conflict.

By linking molecular epigenetic decay rates to systemic thermodynamic limits, the HEAM suggests that "trained immunity" creates a structural rewiring where scarred myeloid cells outcompete neural networks for glucose. This "obligate post-viral myeloid glucose theft" offers a parsimonious, unified explanation for cognitive fatigue and post-exertional malaise. The author posits that this systemic diversion parallels frameworks like the vagus nerve localized exhaustion hypothesis, providing a deterministic proof of concept for how acute innate immune activation can lead to irreversible post-inflammatory pathology through epigenetic hysteresis.

Limitations
The author acknowledges that the framework relies on simplifying assumptions inherent to deterministic ODEs, including the assumption of a spatially well-mixed system (abstracting blood-brain barrier transport kinetics) and the aggregation of physiological buffers into singular continuous variables. The model does not explicitly account for CNS counter-regulatory feedback loops, suggesting that future multi-compartment stochastic models are required to fully map spatial dynamics.

Technical Summary: A Deterministic Framework for Neuroimmune Energetic Allocation via Epigenetic Hysteresis

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