HRH3 and Alzheimer disease: Interestingly, RNA sequencing data from the Splice-O-Mat platform showed that hH3R-445, hH3R-453, hH3R-373, hH3R-399a, hH3R-399b, hH3R-269, and hH3R-56 were expressed at higher levels in the brains of individuals with an opioid use disorder (OUD) or Alzheimer’s disease symptoms as compared to the control population (Figure 2).