W20/XD4-SPIONs reduced GFAP-positive area in the cortex and hippocampus by 65.2% and 51.6%, respectively (Fig. 4c), and Iba-1-positive area by 64.1% and 79.6% (Fig. 4d) in the brains of AD mice, indicating that W20/XD4-SPIONs significantly attenuated astrocytosis and microgliosis in AD mouse brains. The gene discussed is GFAP; the disease is Alzheimer disease.