Mental disorders and the decline in cognitive abilities with age represent a growing health challenge that burdens health systems around the world. Dementia, according to the World Health Organization in its update published in 2025, ranks seventh among the causes of death globally, and is one of the most prominent obstacles that limit the ability of the elderly to perform their daily activities and tasks.
The organization’s data indicates that about 57 million cases of dementia have been recorded around the world, of which Alzheimer’s disease constitutes between 60% and 70%. In the absence of an effective and appropriate treatment for dementia so far, it is increasingly important to search for nutritional and lifestyle methods that may help slow the deterioration of mental health and preserve brain function for as long as possible.
Virgin olive oil and enhance mental cognition
Scientists view diet as one of the important pathways to supporting mental health and reducing the rate of cognitive decline associated with aging. Among the food ingredients that have received extensive research attention, olive oil stands out, especially virgin and extra virgin olive oil, because of the bioactive compounds it contains.
In this context, researchers from Spain and the United States of America conducted a prospective study on 656 elderly people, aged between 55 and 75 years, with the aim of evaluating the effect of consuming different types of olive oil on cognitive functions, and studying the possible relationship between this effect and the diversity of beneficial bacteria in the intestines, or what is known as the microbiota.
The follow-up lasted two full years, and the study focused on elderly people who are more vulnerable to deterioration in memory and mental functions compared to others.
How was the participants’ diet evaluated?
Dietitians followed the participants’ diet annually, using nutritional questionnaires based on criteria included in Spanish food content tables. The researchers focused specifically on 3 types of olive oil:
Virgin olive oil and extra virgin olive oil:
The acidity of virgin olive oil is less than or equal to 2%, while the acidity of extra virgin olive oil does not exceed 0.8%. This last type is characterized by containing high levels of polyphenols, tocopherols, and a number of bioactive compounds. It is also subjected to minimal processing, which helps it retain most of its active ingredients.
Refined olive oil:
Its acidity is less than or equal to 0.3%, but it undergoes processing processes that lose most of its bioactive components.
Olive pomace oil:
It is produced from oils extracted from olive waste after pressing, and its acidity is less than or equal to 0.3%.
The participants were divided into 3 groups according to the total calories they obtained from different types of olive oil: a low-consumption group, a medium-consumption group, and a third high-consumption group.
Accurate tests to measure memory and concentration
The researchers assessed participants’ cognitive functions at the start of the study, then reassessed two years later, using a comprehensive battery of neurocognitive tests. These tests included:
The Mini-Mental State Test, the Clock Drawing Test, the Verbal Fluency Test, the Digit Memory Capacity Test, and the Tracking Test.
The researchers also collected stool samples from the participants to analyze the composition of their intestinal bacteria, with the aim of identifying the types of bacteria present in them, and to find out whether they play a role in the relationship between olive oil consumption and improved mental functions.
What did the results show?
The results revealed that participants who consumed the three types of olive oil within the highest consumption category recorded an improvement in overall and general cognitive and mental functions, in addition to an improvement in the level of concentration after two years of follow-up.
Overall cognitive functions mean a person’s mental performance at a given time, such as memory, language, and attention. General cognitive functions reflect the brain’s ability that affects various mental skills, such as learning, thinking, and problem solving.
The researchers also noted that the improvement was related to the dose; The more olive oil consumed, the greater the health benefit recorded.
As for consumption of virgin and extra virgin olive oil, it was associated with improved general and overall cognitive functions, in addition to executive functions, which are the mental skills responsible for controlling thinking and daily reactions, in addition to improved language skills.
The researchers found that the amount of mental improvement increased with increased consumption of extra virgin and extra virgin olive oil. This improvement also remained consistent even after the results were re-analyzed using different statistical methods and strategies, which enhances the strength and reliability of the results.
In contrast, the results showed that consumption of olive pomace oil and refined olive oil was associated with a decrease in the level of general and overall cognitive functions, as well as executive and linguistic functions.
Olive oil and intestinal microbiota
Based on the analysis of stool samples, researchers tried to understand the relationship between gut bacteria and the effect of olive oil on the brain. The results indicated that olive oil may indirectly affect brain health by causing positive changes in the distribution and diversity of the intestinal microbiome.
Extra virgin olive oil has helped promote the growth of a type of beneficial bacteria in the intestines, known as Adlercruzia. The researchers found that these bacteria were responsible for about 20% of the total effect of olive oil on cognitive functions.
The researchers believe that this improvement in the bacterial environment within the intestine reflected positively on the levels of cognitive and mental functions in the elderly during two years of follow-up.
On the other hand, an inverse relationship was observed between the consumption of refined olive oil and olive pomace oil and the deterioration of participants’ mental abilities.
How do scientists explain this effect?
Scientists attribute the remarkable effect of virgin olive oil on the brain to it containing high percentages of bioactive compounds, most notably multiple phenols, such as hydroxytyrosol, oleuropein, and secoiridoides.
These compounds are characterized by their ability to cross the blood-brain barrier, allowing them to directly affect brain cells. These compounds contribute to reducing oxidative stress and alleviating neuroinflammation associated with increased risk of Alzheimer’s disease and degenerative diseases in the brain.
These compounds also help inhibit the accumulation of beta-amyloid proteins and reduce the formation of tau protein, two proteins specifically linked to Alzheimer’s disease. This is done by stimulating the process of autophagy, which is a mechanism that the body uses to get rid of proteins that are harmful to the health of brain cells.
The effect of olive oil is not limited to the brain directly, but also extends to the intestines, as it helps promote the growth of beneficial bacteria and inhibit the growth of harmful bacteria, which contributes to reducing inflammation and achieving the required intestinal balance.
Phenolic compounds in virgin olive oil also stimulate intestinal bacteria to produce bioactive compounds, such as short-chain fatty acids, which have the ability to reduce oxidative stress and neuroinflammation, and improve permeability across the blood-brain barrier.
Thus, these mechanisms integrate to support mental and cognitive functions and protect nerve cells from damage.
Strengths and limitations of the study
Despite the importance of the findings, the researchers point out that the study does not prove a direct causal relationship between olive oil and improved cognitive function or a change in the gut microbiota.
The strengths of the study are the comprehensive assessment of cognitive functions, the two-year follow-up, the detailed methodology, and the precise data collected on the participants.
But on the other hand, there remain some restrictions; Among them is the possibility that there are other factors that may affect the results despite controlling for many variables, in addition to the fact that the sample was limited to a group that lives in an area where there is a lot of olive oil use, which may limit the generalization of the results to other societies.
There was also no direct comparison between olive oil and other food oils to determine the true size of the effect, which partially weakens the results.
Therefore, the researchers emphasized that these results are still in their early stages, and recommended conducting more long-term clinical studies, with the aim of developing new nutritional strategies aimed at maintaining brain health and mental skills by supporting the bacterial environment in the intestine.
Olive oil and brain health in people under 55 years of age
Scientific interest in olive oil is not limited to the elderly only. In 2023, Frontiers in Nutrition published a systematic review that aimed to evaluate the effect of olive oil on mental and cognitive health in people under the age of 55 years.
The researchers reviewed the results of 11 studies published on reliable scientific platforms until August 2023, and concluded that eating olive oil was associated with positive changes in cognitive and mental abilities over time.
These effects included improving brain health, supporting mental processes such as remembering, paying attention, and controlling reactions, in addition to reducing the risk of cognitive deterioration in people who regularly consume it.
But this review also pointed out some limitations; Many studies relied on self-administered nutritional questionnaires, which makes the data vulnerable to bias and error.
There was also wide heterogeneity between studies, which limited the possibility of performing a rigorous meta-analysis. Most studies included a limited number of randomized clinical trials, which reduces researchers’ ability to generalize results.
Phenolic compounds…the potential password
In another review published in July 2023 in the journal Antioxidants (Basel), scientists from research centers and universities in Spain and Italy investigated the potential protective role of olive oil and its phenolic compounds, especially hydroxytyrosol, against age-related cognitive decline.
The review included epidemiological studies, pre-clinical studies, clinical studies and randomized trials.
The results showed that phenolic compounds in olive oil may protect the brain from cognitive decline by reducing oxidative stress and alleviating neuroinflammation, especially in pre-clinical studies.
In human studies, the evidence directly linking the multiple phenolic compounds in olive oil and improved cognition was limited and relatively weak. The review indicated that the effect of olive oil on the heart and brain may be slight in some cases, but it may depend to a large extent on the amount of oil consumed.
The researchers pointed out that most of the included studies did not clearly distinguish between types of olive oil, whether refined or virgin, which makes it difficult to determine the source of the positive health effect.
Some studies also assumed that the participants’ diet remained constant during the research period, while the participants may have changed their dietary pattern, which weakens the accuracy and reliability of the results.
Potential therapeutic prospects
In November 2025, a recent scientific review revealed potential biological mechanisms through which olive oil phenolic compounds may influence Alzheimer’s disease.
The review indicated that extra virgin olive oil may alleviate mental and cognitive dysfunctions, and reduce pathological indicators associated with some degenerative cognitive diseases, most notably Alzheimer’s.
These effects include inhibiting the accumulation of harmful proteins, such as amyloid and tau, alleviating neuroinflammation, reducing oxidative stress, and promoting the formation of new neurons.
This review was based on laboratory and pre-clinical studies, conducted by researchers from China and published in the journal Frontiers in Nutrition. The researchers concluded that it is necessary to conduct future human research to confirm these results, and to study the possibility of developing drug formulations based on the phenolic compounds found in olive oil, with the aim of slowing the progression of Alzheimer’s disease.
