In this study, we aimed to examine the potential impact of phosphoglycerol dihydroceramide (PGDHC) isolated from the periodontal pathogen Porphyromonas gingivalis on the key features of AD pathogenesis, including amyloidogenesis, phosphorylation of tau protein, and cellular senescence, using in vitro models of AD. The gene discussed is MAPT; the disease is Alzheimer disease.