薬理と治療

Abstract

Objective　The present study was conducted to explore the effects of a supplementary diet containing heat-killed cells of Bifidobacterium longum N61（BL diet）on memory and other neurocognitive functions in the healthy elderly with perceived memory impairment. Methods　Sixty eligible subjects between the ages of 50 and 69 years were enrolled in this randomized, double-blind, placebo-controlled trial and assigned to receive a daily dose of 400 mg of BL diet containing 1010 heat-killed cells of B. longum N61（BL group, n＝30）or placebo （placebo group, n ＝30）for a period of 12 weeks. Efficacy on neurocognitive functions was assessed using a computerized neurocognitive test battery, Cognitrax basic package, at baseline and after 12 weeks of treatment （post-treatment）. Statistical analyses followed the per-protocol principle. Results　All subjects except one in the BL group completed the study, although three in the placebo group were excluded from the efficacy analyses due to protocol violations. Analysis of the fully evaluable cohort indicated that there were no significant differences between the two groups on any of the neurocognitive domains assessed. However, there were trends favoring BL in scores for 5 of 11 neurocognitive domains（i,e. visual memory, psychomotor speed, reaction time, processing speed, and motor speed）, of which the magnitude of improvement of visual memory domain scores reached a near-significant level（P＝0.092）at post-treatment. Moreover, subgroup analyses revealed that the BL subset exhibited significantly better performance in the visual memory domain（P＝0.040）compared with the placebo subset in healthy old adults with low-normal memory function. During the study, no BL-induced side effects were observed. Conclusion　The results suggest that the BL diet may have some beneficial effects on visual memory domain performance in healthy old adults with perceived memory impairment and lowered memory function（. UMIN-CTR╱UMIN000033917）