Beneficial effects of a nobiletin-rich formulated supplement of Sikwasa (C. depressa) peel on cognitive function in elderly Japanese subjects; A multicenter, randomized, double-blind, placebo-controlled study

Abstract

Background: Nobiletin exerts beneficial effects on cognitive function in various animal models of Alzheimer's disease. The present study aimed to investigate the benefits and safety of a combination food of nobiletin-rich extract from C. depressa peel for healthy elderly subjects. Methods: The nobiletin-containing test food (Nobilex®) comprised high-purity nobiletin powder combined with dried root powder of K. parviflora and dried lead powder of P. japonicum and was administered to elderly Japanese subjects once a day for 16 weeks. The Japanese version of the Wechsler Memory Scaled-Revised (WMS-R) was used as a primary evaluation item for the assessment of global memory. Data from a protocol-matched population (Per Protocol Set: PPS) (n = 108) were analyzed. Results: The scores of “general memory” or “visual memory” in the indices of WMS-R were significantly higher in the nobiletin-containing test food group than in the placebo group. The difference in the total WMS-R score was significantly higher in the test-food group (9.0 ± 7.20) than in the placebo group (5.9 ± 7.70). An age-stratified analysis of the WMS-R test showed similar changes in subjects aged ≦74 years to those in the overall subject population. In the stratified analysis involving subjects with an MMSE-J score of between 24 and 28, the “figural memory” subscale score in WMS-R was significantly higher in the test food group than in the placebo group. Conclusion: The present results indicate that the nobiletin-containing test food is beneficial for improving memory dysfunction in healthy elderly subjects.