Functional Pathological Features and Molecular Markers in Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder defined not only by amyloid-β plaques and tau pathology but also by several interacting processes that drive disease progression. These include neuroinflammation, neuronal cell death, synaptic dysfunction, blood-brain barrier (BBB) breakdown, and myelin and axonal damage. Together, they lead to neuronal loss and cognitive decline. In this review, we present a cell-centered framework linking these processes with key molecular markers. Neuroinflammation is driven by activated microglia and astrocytes and is associated with markers such as Iba1, CD68, GFAP, and C3, along with cytokines including IL-1β and TNF-α. Neuronal cell death occurs through apoptosis, ferroptosis, pyroptosis, and necroptosis, with markers such as caspase-3, GPX4, GSDMD, and MLKL. Synaptic dysfunction is reflected by reduced synaptic proteins, including synaptophysin and PSD-95. BBB breakdown increases permeability and reduces clearance of toxic molecules. Myelin and axonal damage, associated with MBP and NfL, disrupt neural connectivity. These processes are dynamically interconnected and may contribute differently across disease stages. This integrated cell-centered and systems-level framework provides insight into AD progression while highlighting potential biomarkers and therapeutic targets for diagnosis, disease monitoring, and therapeutic intervention.