Extra Virgin Olive Oil Improves Learning and Memory in SAMP8 Mice

Polyphenols are potent antioxidants found in extra virgin olive oil (EVOO); antioxidants have been shown to reverse age-and disease-related learning and memory deficits. We examined the effects of EVOO on learning and memory in SAMP8 mice, an age-related learning/memory impairment model associated with increased amyloid-beta protein and brain oxidative damage. We administered EVOO, coconut oil, or butter to 11 month old SAMP8 mice for 6 weeks. Mice were tested in T-maze foot shock avoidance and one-trial novel object recognition with a 24 h delay. Mice which received EVOO had improved acquisition in the T-maze and spent more time with the novel object in one-trial novel object recognition versus mice which received coconut oil or butter. Mice that received EVOO had improve T-maze retention compared to the mice that received butter. EVOO increased brain glutathione levels suggesting reduced oxidative stress as a possible mechanism. These effects plus increased glutathione reductase activity, superoxide dismutase activity, and decreased tissue levels of 4-hydroxynoneal and 3-nitrotyrosine were enhanced with enriched EVOO (3x and 5x polyphenols concentration). Our findings suggest that EVOO has beneficial effects on learning and memory deficits found in aging and diseases, such as those related to the overproduction of amyloid-beta protein, by reversing oxidative damage in the brain, effects that are augmented with increasing concentrations of polyphenols in EVOO.