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 monotonictrajectory from health to degeneration. In contrast, the Ecological Homeostasis (EH) framework treatsPD as a failure of multi-scale regulatory systems to maintain viable neural–immune–metabolic dynamicswithin a bounded region of state space under persistent perturbation. Neurodegeneration is interpretednot as linear decay but as a change in the residence time of the system within competing regimes ofactivity, driven by slow parameter drift and noise.We formalise this perspective using Itô stochastic differential equations (SDEs) to define a viabilityenvelope V(p), a soft constraint region S_ε(p), and a set-valued attractor A(p) under parametervector p. Within this framework, PD is characterised as an Early Latent Bistability (ELB) regime: thesystem's dynamics are compatible with both a dopaminergic-coherent regime and a pathologicalinflammatory–oxidative regime, but control parameters still allocate most residence time to thehealthy-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 noisefloor; and (iii) Capacity — mean exit time E[τ] from the healthy viability region. We instantiate theseconstructs in a mechanistic PD case study focused on a chronic inflammation → iron dysregulation →oxidative variance → resilience erosion cascade. We then propose a hierarchical, person-specificCoherence Index (CI) for longitudinal studies. The EH framework shifts research questions from 'Whatcauses PD?' to 'Under what conditions is dopaminergic coherence viably maintainable, for whichindividuals, and for how long?'