Structural Medicine v1.5: Control, Optimization, and Cost-Constrained Irreversibility in Structural Lifespan Dynamics with ADNI Validation

We present Structural Medicine v1.5, a minimal and unified framework for describing emergence, stability, collapse, and control in structural lifespan dynamics. The framework extends previous versions by introducing intervention-dependent decay and optimal control, transforming the model from a descriptive formulation into a control-theoretic system. The dynamics are defined over a structural state space consisting of structural persistence F(t), connectivity Γ(t), and structural density C(t), with evolution governed by coupled nonlinear differential equations. A key contribution of v1.5 is the introduction of cost-constrained intervention through a state-dependent decay function λ(U) = λ₀ + kU², which captures the non-monotonic nature of intervention: moderate intervention stabilizes the system, while excessive intervention accelerates structural collapse. The framework is validated using real-world longitudinal data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). We demonstrate that the empirically estimated decay parameter λ increases monotonically across diagnostic groups (CN → SMC → EMCI → LMCI → AD), with strong statistical significance (p ≪ 0.001). This result establishes a direct connection between theoretical structural dynamics and observable clinical progression. All figures are reproducible via the provided Python script, and the framework is designed to be minimal, interpretable, and extensible across biological, cognitive, and artificial systems.