HRH3 and Alzheimer disease: Considering all these evidences, BPSD as heterogeneous range of psychiatric behaviors and symptoms arising from the presence of dementia alongside with progressive decline in cognitive functions, suggests that H3R antagonists may function to improve BPSD through enhancing cognitive performance (Witkin and Nelson, 2004; Dekker et al., 2018) as in related AD, MCI, and ASD.