Sodium benzoate, a D‐amino acids oxidase inhibitor, for the treatment of mild cognitive impairment: Pooled data from three randomized, double‐blind, placebo‐controlled trials

BACKGROUND: Previous studies found that sodium benzoate (the pivotal D-amino acid oxidase [DAO] inhibitor) improved cognitive function in patients with mild Alzheimer's disease (AD); however, its efficacy for mild cognitive impairment (MCI) remained inconclusive. This study aims to evaluate the efficacy and safety of sodium benzoate in treating amnestic MCI (aMCI). METHODS: Data were pooled from three randomized, double-blind, placebo-controlled trials. One hundred thirty-three patients with aMCI were enrolled from three major medical centers in Taiwan to receive 24-week treatment of 250-1500 mg/day of sodium benzoate or placebo. The cognitive outcome was Alzheimer's disease assessment scale-cognitive subscale (ADAS-cog), and the functional outcome was Instrumental Activities of Daily Living (IADL). Both were measured at weeks 0, 8, 16, and 24. RESULTS: Among 133 participants, sodium benzoate therapy improved ADAS-cog scores more than placebo (P = 0.033 at week 16, 0.026 at week 24). Among 84 women, benzoate surpassed placebo in ADAS-cog (P = 0.046 at week 16, 0.029 at week 24), as well as IADL (P = 0.043 at week 24). In contrast, among 49 men, the two treatment groups did not differ significantly in both ADAS-cog and IADL scores. Both sodium benzoate and placebo were well tolerated and benzoate therapy produced no additional side effect. CONCLUSIONS: This study is the first to demonstrate that a DAO inhibitor, sodium benzoate herein, can enhance overall cognitive function in MCI individuals. Furthermore, it can improve female patients' IADL. The finding lends support for DAO inhibition as a novel approach for early dementing processes.