GABA released from reactive astrocytes affects nearby neurons, and increased enzyme activity of MAOB has been reported in neurodegenerative disease models such as Parkinson’s disease (Mallajosyula et al., 2008) and Alzheimer’s disease (Chun et al., 2020; Ju et al., 2022). Here, MAOB is linked to early-onset autosomal dominant Alzheimer disease.