Background: Evidence supports a role of α4β2 receptors in Alzheimer's disease (AD). Methods: This Korean, multicenter, double-blind, two-period (6 weeks each), crossover study randomized participants to the order in which they received varenicline (1 mg twice daily) and placebo. Assessments included AD Assessment Scale-Cognitive Subscale (ADAS-Cog) 75, Neuropsychiatric Inventory (NPI), adverse events (AEs) and Columbia-Suicide Severity Rating Scale (C-SSRS). Results: For varenicline versus placebo (n = 66 randomized), there was no significant difference in the week 6 least square (LS) mean ADAS-Cog 75 total score (primary endpoint; 18.07 vs. 18.49; p = 0.3873) and a slight worsening in the week 6 LS mean NPI (3.82 vs. 2.55; p = 0.0468), primarily driven by decreased appetite/eating. Common treatment-related AEs were nausea (23.3; 3.4%), vomiting (15.0%; 0) and decreased appetite (15.0; 6.8%). Conclusions: Varenicline did not improve cognition, behavior or global change in this population. The most frequent varenicline-associated AEs were gastrointestinal; psychiatric AEs were rare and similar between the groups.

Keywords:
Alzheimer’s disease, Cognition, Crossover study, Partial agonist, Receptor activation, Varenicline
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