Synaptic dysfunction in AD, characterized by decreased dendritic spine density and reduced expression of synaptic proteins such as postsynaptic density 95 (PSD95) and synaptophysin (Syp), manifests years before the appearance of overt clinical symptoms and is strongly correlated with the severity of memory impairments (Bertoni-Freddari et al., 1990; de Pins et al., 2019; Han et al., 2024; Jack and Holtzman, 2013; Long et al., 2021; Masliah et al., 2001). The gene discussed is SYP; the disease is Alzheimer disease.