Incoherent Failure of the Q2→Q4 Cortical Cascade: A Field-Theoretic Mechanistic Hypothesis for Shaw's ADHD Remission Paradox

v20: Multisite rs-fMRI analysis (ADHD-200, n=346, 4 sites), probabilistic tail analysis (13% left-tail), quartile decomposition (Q1:13%/Q2-Q4:29% each), Figures 4-5 embedded, ethical framework §6.4 (WIN-WIN, French precautionary principle), 8 falsifiable predictions, Sibley et al. 2024, Cao et al. 2024, Tomasi et al. 2025. Submitted to Frontiers in Human Neuroscience 27 May 2026. We propose a mechanistic hypothesis for the Shaw ADHD remission paradox — the observation that apparent cortical normalization in adolescence does not guarantee functional remission in adulthood. Within the Cortical Informational Field Theory (CIFT) framework, we formalize two failure modes: coherent failure (Persistent ADHD: Q2+Q4 both subcritical) and incoherent failure (Remitter: Q4 subcritical without Q2 scaffolding). Cortical field simulations (n=15, γ_W=0.15) demonstrate that Remitters show significantly lower MI(E,W)|Q4 than Persistents (t=−4.97, p<0.001, d=−1.81), a finding robust across 9 parameter sweeps. Pharmacological screening of ADHD-200 TCIC (ds002424, n=147) reveals asymmetric drug effects: MPH/AMP partially stabilize Q4 dynamics with no detectable effect on Q2 — the boundary condition that determines long-term gradient coupling. Five falsifiable predictions are proposed