Astrocytes and Microglia in Alzheimer's Disease: Friends, Foes, or Both?

Alzheimer's disease (AD), the most prevalent form of dementia, is neuropathologically defined by the accumulation of extracellular amyloid-beta (Aβ) plaques and intracellular neurofibrillary tangles of hyperphosphorylated tau. Although traditionally viewed as a neuron-centric disorder, increasing evidence underscores the pivotal role of glial cells-particularly microglia and astrocytes-in AD pathogenesis. Once regarded as passive support cells, glia are now recognized as active participants in neuroinflammation, synaptic dysfunction, and disease progression. Microglia, the resident immune cells of the central nervous system, and astrocytes, key regulators of homeostasis and neurotransmission, undergo significant phenotypic changes in response to AD pathology. These include polarization into pro-inflammatory states, impaired clearance of pathological proteins, and detrimental cross talk that amplifies neuroinflammation and neuronal injury. This review synthesizes current literature on the dualistic roles of glial cells in AD, highlighting their contributions to Aβ and tau pathology, synapse loss, demyelination, neurotransmission deficits, and the neuroinflammatory cycle. Emphasis is placed on the dynamic polarization of glia, the reciprocal interactions between microglia and astrocytes, and their combined impact on neurodegeneration. We further explore both pharmacological and non-pharmacological therapeutic approaches targeting glial function, including anti-inflammatory agents, senolytics, deep brain stimulation, exercise, and dietary interventions. By elucidating the multifaceted involvement of glial cells in AD, this review aims to spotlight emerging therapeutic strategies that go beyond neuronal targets, offering new hope for modifying disease progression and improving patient outcomes.