A Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy of Teprenone in Patients with Alzheimer's Disease

Background: Teprenone (geranylgeranylacetone), an anti-ulcer agent, has been reported to inhibit amyloid-beta increase, senile plaque formation, and neuronal degeneration, and improve memory in mouse models of Alzheimer's disease (AD). Objective: We conducted a randomized, double-blind, placebo-controlled study to ascertain teprenone's therapeutic ability for AD. Methods: Patients with mild to moderate AD, with a Mini-Mental State Examination (MMSE) score of 13 to 26, were randomly allocated into two groups depending on the administered drug: donepezil + placebo (placebo group) and donepezil + teprenone (teprenone group). The primary and secondary endpoints included changes in scores of the Japanese version of the AD Assessment Scale-cognitive subscale (ADAS-J cog) and other evaluations, respectively, including MMSE scores, during a 12-month period after the first administration. Results: Forty-two and thirty-seven patients were allocated to the teprenone and placebo groups, respectively. ADAS-J cog score changes were not different between groups (placebo, 0.6 +/- 0.8; teprenone, 0.4 +/- 0.8; p = 0.861). However, MMSE scores significantly improved in the teprenone group (placebo, -1.2 +/- 0.5; teprenone, 0.2 +/- 0.5; p = 0.044). Subgroup analysis considering the severity of medial temporal area atrophy revealed that this improvement by teprenone was significant in patients with mild (p = 0.013) but not with severe atrophy (p = 0.611). Adverse events were observed in 17.8 and 10.4% of patients in the placebo and teprenone group, respectively. Conclusion: Teprenone may be effective for AD when administered before atrophy progression in the medial temporal areas.