Aging is accompanied by profound alterations in immune function, termed immunosenescence, and by a chronic, low-grade inflammatory state known as inflammaging. These processes are increasingly recognized as central drivers of age-related neurodegenerative diseases, including Alzheimer’s Disease, Parkinson’s Disease, Amyotrophic Lateral Sclerosis and Multiple Sclerosis. In the central nervous system, senescent microglia and astrocytes lose their homeostatic and neuroprotective functions, while systemic immune aging and blood–brain barrier dysfunction further amplify neuroinflammation and impair protein aggregate clearance. This sustained pro-inflammatory environment promotes synaptic dysfunction, neuronal loss and cognitive decline.