The Role of T Cells in Alzheimer's Disease.

Alzheimer's disease (AD) is a global neurodegenerative disorder characterized by progressive cognitive decline. Its core pathology involves neurofibrillary tangles mediated by hyperphosphorylated tau protein and senile plaques formed by extracellular deposits of β-amyloid. As the global incidence of AD continues to rise, human health faces a serious threat. However, the complexity of its pathogenesis poses significant challenges to current prevention and treatment strategies. Recent studies reveal that T cells, as key components of the adaptive immune system, exhibit abnormalities in both quantity and function within the brains of AD patients. They infiltrate brain parenchyma through multiple pathways-including the blood-brain barrier, choroid plexus, and meningeal lymphatics-and are deeply involved in AD pathology. In this review, we first introduce recent discoveries in the pathogenesis of AD, including tau protein, β-amyloid plaques, and neuroinflammation. We then describe the immune mechanisms and infiltration pathways of T cells in AD. Finally, we focus on the mechanisms by which different T cell subtypes contribute to brain damage in AD, aiming to provide a theoretical foundation for developing AD therapies guided by neuroimmune homeostasis.