HRH3 and early-onset autosomal dominant Alzheimer disease: Interestingly, in the past decades histamine H3 receptor (H3R) antagonists/ inverse agonists obtained an enormous attention regarding their possible diverse applications in the treatment of different neuropsychiatric diseases including epilepsy, dementia, Alzheimer’s disease, autism spectrum disorder and cognitive impairment [16,17,18,19,20,21,22,23].