HRH3 and Alzheimer disease: Accordingly, several H3R antagonists improved cognitive deficits induced with ketamine and MK801 in numerous animal models (Browman et al., 2004), suggesting that these H3R antagonists may also be effective in neurodegenerative disorders, e.g., AD (Witkin and Nelson, 2004; Bardgett et al., 2010; Charlier et al., 2013; Sadek and Stark, 2015; Sadek et al., 2016b).