Neurodegeneration has multi-scalar impacts, including cognitive, anatomical, and functional disruptions. Disease-specific convergences among these levels can be traced by targeting higher-order domains. In particular, motor and social impairments in Parkinson’s disease (PD) and behavioral variant frontotemporal dementia (bvFTD) are echoed by deficits in action and social verbal meanings, respectively. Yet, no single ecological paradigm can capture those signatures. Here, combining voxel-based morphometry, fMRI, and EEG connectivity with a naturalistic language task, we describe disease-specific signs of PD, bvFTD, and Alzheimer’s disease (AD). We assessed comprehension of four stories highlighting action, non-action, social, and non-social events. PD patients presented selective action-text deficits related to the volume of action-observation regions, connectivity across motor-related and multimodal-semantic hubs, and frontal EEG hypo-connectivity. BvFTD patients exhibited selective social-text deficits, associated with atrophy and spatial connectivity patterns along social-network hubs, and right fronto-temporal EEG hypo-connectivity. AD patients showed impairments in all stories, with widespread atrophy and spatial connectivity patterns, and heightened right occipito-temporal EEG connectivity. Briefly, our ecological task captures multimodal double dissociations between PD and bvFTD with no comparable pattern in AD, opening new avenues for their neurocognitive typification.