Parkinson's Disease as Early Latent Bistability: An Ecological Homeostasis Working Model

Abstract

Conventional approaches to Parkinson's disease (PD) seek proximal causes — misfolded proteins,
mitochondrial defects, environmental toxins — and often implicitly assume a roughly monotonic
trajectory from health to degeneration. In contrast, the Ecological Homeostasis (EH) framework treats
PD as a failure of multi-scale regulatory systems to maintain viable neural–immune–metabolic dynamics
within a bounded region of state space under persistent perturbation. Neurodegeneration is interpreted
not as linear decay but as a change in the residence time of the system within competing regimes of
activity, driven by slow parameter drift and noise.
We formalise this perspective using Itô stochastic differential equations (SDEs) to define a viability
envelope V(p), a soft constraint region S_ε(p), and a set-valued attractor A(p) under parameter
vector p. Within this framework, PD is characterised as an Early Latent Bistability (ELB) regime: the
system's dynamics are compatible with both a dopaminergic-coherent regime and a pathological
inflammatory–oxidative regime, but control parameters still allocate most residence time to the
healthy-like regime. ELB is explicitly defined as a model class whose topology includes, as special cases,
both true bistability and critical slowing near a single, deforming attractor.
We define the EH Triad: (i) Geometry — distance Δ(x;p) to regulatory boundaries; (ii) Resilience —
stochastic stability ratio α/β, where α measures corrective regulatory strength and β the effective noise
floor; and (iii) Capacity — mean exit time E[τ] from the healthy viability region. We instantiate these
constructs in a mechanistic PD case study focused on a chronic inflammation → iron dysregulation →
oxidative variance → resilience erosion cascade. We then propose a hierarchical, person-specific
Coherence Index (CI) for longitudinal studies. The EH framework shifts research questions from 'What
causes PD?' to 'Under what conditions is dopaminergic coherence viably maintainable, for which
individuals, and for how long?'