SMPD1 and memory impairment: 23A12C3 efficiently decreased plasma ASM activity (Fig. 6g), leading to reduction of pathogenic Th17 cells in the spleen, blood, and brain, and further showed preventive effects on microglia and astrocytes activation, increase of pro-inflammation, Aβ accumulation in APP/PS1 mice, and on memory impairment in these male mice (Fig. 6h–p).