Dementia is a syndrome associated with a decline in cognitive function that is usually chronic or progressive.
It may result from injuries or health conditions, including Alzheimer’s disease (AD), stroke, and disorders affecting blood vessels in the brain, among others. Still, the cause of dementia is not fully understood.
The WHO suggests that more than 55 million people currently live with dementia. Moreover, this number is expected to increase to 139 million in 2050.
With the prevalence of dementia expected to rise, identifying preventative strategies and effective treatments is critical.
One area of research receiving increased attention from scientists is the role diet plays in reducing dementia risk. Specifically, scientists are interested in the Mediterranean diet — an eating pattern that follows the traditional cuisine of people living in the Mediterranean region.
Although some evidence suggests this diet may offer protection against cognitive decline, new research from scientists at Lund University in Sweden found no significant association between a conventional or Mediterranean diet and a reduced risk of dementia.
The scientists suggest that diet alone may not have a strong influence on cognitive function.
The study was published on October 12 in the online issue of the journal Neurology.
To investigate the role diet plays in the development of dementia, as well as dementia related to Alzheimer’s disease and vascular dementia, Lund University researchers analyzed dietary data from 28,025 people in Sweden over a 20-year timeframe. At the onset of the research, the participant’s average age was 58, and none were diagnosed with dementia.
The participants completed 7-day food journals, detailed food frequency questionnaires, and underwent personal interviews.
At the 20-year follow-up, 1,943 or nearly 7% of the participants were diagnosed with dementia —including Alzheimer’s disease and vascular dementia.
The researchers then examined the participant’s adherence to conventional or Mediterranean diet recommendations. The conventional diet recommendations used by the scientists followed the Swedish nutrition recommendations and guidelines, similar to guidelines in the United States and the United Kingdom. Moreover, the researchers used a modified Mediterranean diet score (mMDS) to calculate the participant’s Mediterranean diet adherence.
In addition to diet adherence, the researchers adjusted for age, gender, education, and lifestyle factors. The team also excluded participants who were diagnosed with dementia within 5 years after the study’s onset.
After vetting the data, the scientists found no significant associations between adherence to conventional dietary recommendations nor to the Mediterranean diet and a reduced risk of all-cause dementia, Alzheimer’s, or vascular dementia.
They also found no evidence that adherence to either diet influenced the presence of Alzheimer’s disease-related biomarkers in a sub-group of 738 participants.
What’s more, identical results were found among individuals with high adherence to dietary recommendations or with high adherence to the Mediterranean diet.
Still, the researchers note that participants who developed dementia over the 20-year study period were older and had lower education levels at the study’s onset compared to those who did not develop the condition. In addition, the individuals who developed dementia also had cardiovascular risk factors and co-morbid health conditions at the study’s onset.
However, because of the study’s limitations, including the possibility of participants not reporting some diet and lifestyle information, the researchers suggest that more investigation is needed to confirm these findings.
In a press release, study author Dr. Isabelle Glans, research and doctoral student at Lund University, said:
“While our study does not rule out a possible association between diet and dementia, we did not find a link in our study, which had a long follow-up period, included younger participants than some other studies, and did not require people to remember what foods they had eaten regularly years before.”
In a study-related editorial, Dr. Nils Peters, a neurologist and professor at the University of Basel in Switzerland, and Dr. Benedetta Nacmias, a professor at the University of Florence in Italy, noted that despite these results, “diet should not be forgotten, and it still matters, notably when it is embedded into a multimodal approach, including other measures, such as vascular risk factor control.”
Although evidence points to the Mediterranean diet as beneficial to overall health, the research on whether it prevents or slows the development of dementia continues to produce conflicting results.
For example, a 2021 study suggests that a multi-domain approach, including diet, physical, cognitive and social activity, may offer the most benefits for cognitive function.
Additionally, a 12-year Australian longitudinal cohort study from 2019 found that the Mediterranean-DASH Intervention for Neurodegenerative Delay diet (MIND), not the Mediterranean diet, was associated with reduced risk of cognitive impairment.
By contrast, a systematic review of research published in 2014 suggests that higher adherence to the Mediterranean diet is associated with a reduced risk of mild cognitive impairment and Alzheimer’s disease.
Moreover, a recent systematic review suggests that following the Mediterranean diet may prevent or delay cognitive disorders and improve cognitive function in healthy adults.
Karen D. Sullivan, Ph.D., ABPP, creator of the I CARE FOR YOUR BRAIN education program, not involved in the study, told Medical News Today:
“The Mediterranean diet has accumulated a solid body of evidence linking this way of eating to the prevention of chronic diseases and improved vascular health via the resulting stable blood glucose and blood pressure levels, healthy lipid profile, and low systemic inflammation.”
Kimberly Gomer, RD, LDN, director of nutrition at Body Beautiful Miami, told MNT:
“The physical and cognitive benefits [of the Mediterranean diet] relate not only to what is included in this diet (fish, olive, oil, and vegetables) but what is NOT included, mainly highly processed foods including processed grains, vegetable seed oils (soybean, corn, sunflower, canola, vegetable), and sugar. My thoughts are that if a person consumes omega-3-fats, along with highly processed foods, seed oils, and sugar — they may not have the cognitive and dementia prevention.”
Sullivan suggested that “the most evidence-based brain health diet is a hybrid of the Mediterranean diet, an aptly named acronym called the MIND diet […].”
“The MIND diet focuses on consuming 10 healthy food types regularly (beans, berries, fish, green leafy vegetables, nuts, poultry, olive oil, vegetables, whole grains, wine) while avoiding five specific unhealthy food categories (butter, cheese, fried food [and] fast food, red meats, and sweets [and] pastries),” Sullivan said.
“However, it is important to remember that, as is the case with all diets, the brain-health boosting foods must be consumed in conjunction with other lifestyle choices to have substantial benefits, like consistent cardiovascular exercise, socialization, cognitive stimulation, and meaning-making. No one thing in isolation is […] going to have a robust effect on something as complex as the brain,” she noted.
Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.
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Oct 12, 2022
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Kimberly Drake
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Study says Mediterranean diet may not reduce dementia risk – Medical News Today
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Oct 13, 2022