MAPT and early-onset autosomal dominant Alzheimer disease: The LC undergoes neuron loss in the early stages of many neurodegenerative diseases (Liu et al., 2017; Betts et al., 2019; Galgani et al., 2020), such as Alzheimer’s disease (Grudzien et al., 2007; Giorgi et al., 2017; Kelly et al., 2017) and Parkinson’s disease (Gesi et al., 2000; Vermeiren and De Deyn, 2017) through the accumulation of tau pathology (Braak et al., 2011; Jacobs et al., 2023) and α-synuclein (Braak et al., 2003), respectively.