Soybean-derived phosphatidylserine improves memory function of the elderly Japanese subjects with memory complaints

Abstract

Soybean-derived phosphatidylserine (Soy-PS) is a phosphatidylserine made from soybean lecithin by enzymatic reaction with L-serine. A double-blind, randomized controlled study was conducted to investigate the effects of Soy-PS on the cognitive functions of the elderly Japanese subjects with memory complaints. Seventy-eight elderly people with mild cognitive impairment (50-69 years old) were randomly allocated to take Soy-PS (100 mg, 300 mg/day) or placebo for 6 months. As a result, there was no difference in blood markers and vital signs during Soy-PS treatment and any side effect caused by Soy-PS treatment was not observed. Neuropsychological test scores were similarly increased in all groups including placebo group. However, in the subjects with relatively low score at baseline, the memory scores in PS treated groups were significantly increased against the baseline, while those of placebo group remained unchanged. And the memory improvements in Soy-PS-treated groups were mostly attributed to the increase in delayed verbal recall, a memory ability attenuated in the earliest stage of dementia. In conclusion, Soy-PS used in this study is considered as safety food ingredient and 6 months of Soy-PS supplementation could improve the memory functions of the elderly with memory complaints.

Keywords: delayed verbal recall; elderly; memory functions; phosphatidylserine; soybean.

Fig. 1

The study design and trial profile.

Fig. 2

Effect of Soy-PS on HDS-R performance in high-score and low-score subgroups. Subjects were divided into two subgroups based on their baseline RBMT score. (A) High-score subgroup (RBMT score = 19 or more). (B) Low-score subgroup (RBMT score<19). Values are means ± SEM and shown as changes in score against the baseline. **p<0.01, ***p<0.001 vs baseline, ^$p<0.1, ^#p<0.05 vs placebo group (Steel’s multi-comparison test).

Fig. 3

Effect of Soy-PS on DWR subtest of HDS-R and MMSE in the low-score subgroup (RBMT score<19 at baseline). (A) DWR subtest of HDS-R. (B) DWR subtest of MMSE. Values are means ± SEM and shown as changes in score against the baseline. *p<0.05, **p<0.01, ***p<0.001 vs baseline, ^$p<0.1, ^#p<0.05 vs placebo group (Steel’s multi-comparison test).