Astrocytes in Neurodegeneration: Spatial States, Crosstalk, and Emerging Therapies.

Astrocytes are increasingly recognized as active drivers of neurodegeneration rather than passive responders. Single-cell and spatial transcriptomic analyses reveal that astrocytes occupy heterogeneous, regionally patterned states that align closely with selective neuronal vulnerability. Across Alzheimer's disease, Parkinson's disease, ALS, Huntington's disease, and rare primary astrocytopathies, astrocytes consistently converge on dysfunction across four mechanistic axes: breakdown of glutamate homeostasis, impaired ion and water buffering, lysosomal, and autophagic insufficiency, as well as maladaptive inflammatory-stress signaling. Spatial multi-omics demonstrates that these disruptions are not uniformly distributed but instead map to discrete niches, including plaque-adjacent astrocytes in Alzheimer's disease, CD44-high fibrotic-like astrocytes in the substantia nigra in Parkinson's disease, and EAAT2-low ventral horn astrocytes in ALS, consistent with patterns of selective neuronal vulnerability. Primary astrocytopathies including Alexander disease, vanishing white matter disease, and megalencephalic leukoencephalopathy illuminate the causal power of perturbing individual astrocytic modules, revealing how isolated disruptions in proteostasis, translation control, or ion-water coupling can initiate widespread neurodegeneration. By integrating neuropathological, imaging, and transcriptomic evidence across studies, we derive a consensus-based regional framework of astrocytic vulnerability across neurodegenerative diseases. Together, these findings define a unifying framework in which astrocytes transition from homeostatic regulators to pathological amplifiers, highlighting astrocyte states as tractable, region-specific therapeutic targets and illustrating how integration of spatial atlases with mechanistic insights might help develop a framework for targeted astrocyte therapies.