Effect of a Dietary Supplement Containing Heat—killed Bifidobacterium longum N61 on Neurocognitive Functions in Healthy Old Adults with Perceived Memory Impairment ―A Randomized, Double—blind, Placebo—controlled Trial― Yasuhisa Nagasaki and et al., 薬理と治療, 47, 1677-1688 (2019), DOI:http://dx.doi.org/