Effects of Desert Olive Tree Pearls Containing High Hydroxytyrosol Concentrations on the Cognitive Functions of Middle-Aged and Older Adults

Abstract

The Japanese population has the world’s longest life expectancy but faces the challenge of extending the healthy life expectancy without developing chronic diseases. Therefore, the effectiveness of products derived from olives used in the Mediterranean diet as a potential dietary solution has attracted attention. This study examined the effects of desert olive tree pearls (DOTPs), which contain 162 times more polyphenol hydroxytyrosol than olive oil, on the cognitive function of middle-aged and older adults using the Cognitrax test. Participants (aged 51–82 years) were assigned to the DOTP intake (n = 36) or placebo group (n = 36) in a randomized, double-blind, placebo-controlled, parallel-group study. The participants received 3 g of DOTPs or placebo in olive oil twice daily for 12 weeks. Among cognitive domains, complex attention had a significant time × group interaction effect (p = 0.049) between the DOTP and placebo groups. The simple main effect for this item was significantly different (p < 0.001 and p = 0.572, respectively). Time effects were significant (p < 0.05) for the psychomotor speed, reaction time, cognitive flexibility, processing speed, and executive function domains. Therefore, DOTPs have the potential to alleviate cognitive problems faced by middle-aged and older adults in Japan.