HRH3 and schizophrenia: Nevertheless, a double-blind randomised controlled trial found high dose betahistine, a H1R agonist/H3R antagonist, significantly improved cognitive function in patients with schizophrenia, including verbal and visual learning domains (Wang et al., 2021), while a betahistine challenge examined through fMRI identified modulation of task-evoked activity (van Ruitenbeek and Mehta, 2013).