Network Regulatory Disorders (NRD): A Nosological Framework for Persistent Maladaptive System States in Unexplained Chronic Conditions

Chronic conditions such as ME/CFS, fibromyalgia, Long COVID, IBS, and POTS have long been classified separately — by symptom cluster, organ system, or specialty. This paper argues that a structurally distinct class of these conditions shares a common property that existing frameworks have failed to capture: they are persistent, self-sustaining states of dysregulated physiological network regulation, maintained by internal feedback dynamics rather than by ongoing structural pathology. Network Regulatory Disorders (NRD) is introduced as a formal nosological framework for this class. Rather than adding a new diagnostic label, NRD proposes a different classificatory logic — one grounded in dynamic system properties, in which the primary diagnostic object is regulatory configuration rather than symptom cluster. The framework includes a four-regime subclass taxonomy, a diagnostic instrument for characterizing individual system state, and an intervention logic derived directly from the underlying model. NRD is positioned as a biomedical alternative to "medically unexplained symptoms" and related constructs — including the Dutch institutional categories SOLK and ALK — for conditions in which the primary pathology is dysregulated network state rather than structural lesion or disorder of central representation.