Common alterations to astrocytes across neurodegenerative disorders.

Astrocytes perform multiple functions in the nervous system, many of which are altered in neurodegenerative disorders. In this review, we explore shared astrocytic alterations across neurodegenerative disorders, including Alzheimer's disease, Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and frontotemporal lobe degeneration. Assessing recent datasets of single-nucleus RNA-sequencing of human brains, a theme emerges of common alterations in astrocyte state across disorders including in neuroinflammation, synaptic organization, metabolic support, and the cellular stress response. Immune pathways are upregulated by astrocytes across disorders and may exacerbate neurodegeneration. Dysregulated expression of synaptogenic factors could contribute to synaptic loss, while compromised metabolic support affects neuronal homeostasis. On the other hand, upregulated responses to cellular stress may represent a protective response of astrocytes and thus mitigate pathology. Understanding these shared responses offers insights into disease progression and provides potential therapeutic targets for various neurodegenerative disorders.