MAPT and Alzheimer disease: Studies have shown that various alkaloids eliminate effects such as insoluble and soluble Aβ levels and hyperphosphorylated Tau in the cortex and hippocampus of transgenic AD mice, and they also reduce Tau hyperphosphorylation in several in vitro systems (Durairajan et al., 2012; Liu et al., 2014; Yu et al., 2011).