Chunk #32 — 3. Disruption of functional networks is associated with clinical impairment — 3.4 Neurobiological and clinical implications of network disruption
Research findings reviewed here demonstrate that functional neuroimaging is able to detect distinct patterns of network disruption across the major neurodegenerative diseases (Table 2). These networks are relatively specific to the clinical profiles and may represent intermediate phenotypes between pathology and clinical syndromes. In AD, the topography of Aβ deposition overlaps with the DMN, broadly defined, whereas HP-tau pathology is most prominent within a DMN subnetwork devoted to episodic memory.122 In FTD, the salience network is profoundly disrupted in the behavioural variant. In PD, alpha-synuclein pathology affects the cortico-striatal motor loops. In DLB, forebrain alpha-synuclein deposition has not been matched to a specific network with resting-state techniques, but neuropathological evidence supports an ascent through the brainstem to the limbic and cortical regions associated with clinical symptoms.92 Disruption of ascending brainstem projection systems may soon prove detectable with network-based methods.123
