P2RX4 and Alzheimer disease: These findings may be related to an increased P2X4R expression in the hippocampus of AD patients with severe cognitive impairment, suggesting that upregulated P2X4R may contribute to synaptic dysfunction and microglia phagocytic function (Raouf et al., 2007; Godoy et al., 2019; Han et al., 2020; Nguyen et al., 2020; Trang et al., 2020).