摘要：It has been reported recently that blood levels of plasmalogens (Pls) are decreased in various diseases. However, there are no any clinical trials to examine the effects of Pls on those diseases. I would present our recent study on a therapeutic efficacy of orally administered Pls in mild cognitive impairment (MCI), mild to severe Alzheimer’s disease (AD) and Parkinson’s disease (PD). A 24-week, multicenter, randomized, double-blind, placebo-controlled trial was performed in patients with MCI (n=178) and mild AD (n=98). The study design for moderate AD (n=57) and severe AD (n=18) was 12-week open-labeled, and design for PD (n=10) was 24-week open-labeled. The data showed significant improvements in cognitive function and other clinical symptoms with elevation of blood Pls levels. No adverse events were reported. The baseline levels of plasma ethanolamine plasmalogen (pPE) and erythrocyte pPE in MCI, AD, and PD were significantly lower than those of normal aged. The degree of reduction in blood Pls levels was in the order of MCI≺mild AD≺moderate AD≺severe AD≺PD. The findings suggest that Pls blood levels may be a beneficial biomarker for assessing AD severity. We thus further proposed a new hypothesis for the etiology of AD and other neuropsychiatric disorders.