Extra virgin olive oil may prevent onset of Alzheimer’s disease
Researchers have recently demonstrated that intake of extra virgin olive oil (EVOO) in transgenic mice prevented behavioural changes, preserved synaptic integrity and reduced pathologic markers of Alzheimer’s disease (AD).
In a study using a triple transgenic mouse model of AD, mice given EVOO had a significant improvement in the percentage of spontaneous alterations in Y-maze, a tool for assessing rodent working memory, vs control mice (9 months: 50 vs 40 percent, p<0.05; 12 months: 60 vs 40 percent, p<0.01). [Ann Clin Transl Neurol 2017, doi: 10.1002/acn3.431]
Mice in the study were given EVOO from 6 months of age for 6 months (ie, before the known onset of AD symptoms in this animal model).
After 12 months of observation, mice given EVOO performed better in the probe test, which measures spatial and memory ability, vs control mice (time spent in entry zone: 34 vs 27 seconds, p<0.05).
Pathologically, reduction of Aβ1-40 levels was observed in the brain homogenisates of mice that received EVOO vs control mice. The investigators also found a statistically significant reduction in the amount of amyloid-β peptides deposited in the brains of the EVOO-treated animals (p<0.05).
Phosphorylated tau protein residues, which are also markers of AD pathology, were also significantly decreased in EVOO-treated mice vs controls (AT8, p<0.05; PHF13, p<0.01).
Synaptophysin, a protein that serves as a measurement index for the integrity of connections between neurons, was noted to be significantly higher in EVOO-treated animals vs control mice (p<0.05).
ATG5 and ATG7 activity was also significantly stronger in EVOO-treated mice compared with controls, suggesting induction of autophagy in the EVOO-treated mice (p<0.05).
“Our findings support a beneficial effect of EVOO consumption on all the major features of AD, namely behavioural deficits, synaptic pathology, amyloid-β and tau neuropathology,” the authors said.
“Autophagy activation is a probable mechanism underlying these biological actions. This was based on our hypothesis of potential involvement of a clearing system causing the reduction of both amyloid-β and tau proteins,” they explained.
Autophagy is an intracellular degradation system that delivers cytoplasmic constituents to the lysosome, a cellular component containing enzymes that enable cells to break down protein, nucleic acids, carbohydrates and lipids. [Genes and Dev 2007;21:2861-2873]
The investigators are next planning to investigate the effects of introducing EVOO into the diet of mice at 12 months of age (ie, after the development of AD). The rationale behind this is that when patients consults doctors for suspected AD, the symptoms have already set in.
“We would like to know whether olive oil [EVOO] added at a later time point in the diet can stop or reverse the disease,” the authors said.