According to the World Health Organization, 57 million people had dementia worldwide in 2021. These numbers are increasing; a recent study suggested that more than 150 million people would have the condition by 2050.
A person’s risk of developing some types of dementia is influenced by genetic factors, but lifestyle can also have an effect. Factors that may reduce a person’s risk include being physically active, preventing or managing diabetes, managing blood pressure, correcting hearing loss, not smoking, and limiting alcohol intake.
Eating a healthy diet can help prevent diabetes and manage blood pressure, and there is evidence that it might also directly improve brain health.
Now, a study has added to the evidence that healthy diets are linked to a lower risk of Alzheimer’s disease and dementia.
The study, published in JAMA Network Open, found that older adults who followed a diet with lower inflammatory potential had a reduced risk of developing dementia.
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“Our study was observational, so it cannot prove that changing diet will improve prognosis or prevent dementia, including among people with early biological signs of disease. That said, the findings are consistent with the broader view that diet quality remains relevant for brain health. For older adults, including those concerned about dementia risk, it is reasonable to follow established healthy eating advice.”
— Anja Mrhar, corresponding author, researcher and a PhD student, University of Ljubljana, affiliated at the Aging Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
Emer MacSweeney, MD, CEO and Consultant Neuroradiologist at Re:Cognition Health, not involved in the study, commented:
“One of the most encouraging aspects of this study is that it reinforces the notion that dementia diagnosis is not determined solely by biology. Even among people with blood biomarkers showing a higher risk of Alzheimer’s disease, lifestyle factors may still influence if and when dementia develops.”
Alzheimer’s disease is characterized by the development of amyloid beta plaques and tau tangles, peptides that accumulate in the brain and can interfere with cognitive processes. However, this Alzheimer’s disease pathology is often seen in people without any symptoms of Alzheimer’s, and does not always lead to the condition.
In the latest study, the researchers used blood biomarkers to identify early Alzheimer’s pathology and other indicators of neurodegeneration.
The study used data from the Swedish National study on Aging and Care in Kungsholmen (SNAC-K), a longitudinal study that recruited people aged 60 and over between March 2001 and August 2004. Researchers on SNAC-K followed up those ages over 78 every 3 years, and those ages under 78 every 6 years until November 2019.
In this new study, researchers evaluated participants’ habitual diet using a 98-item food frequency questionnaire.
From these, they assessed adherence to 3 different diet patterns, which Mrhar explained to Medical News Today:
“Unlike the other two indices,” Mrhar told us, “the rEDII is based on how patterns of food intake have been associated with inflammatory markers in previous research. It therefore reflects a more specific inflammation-related dimension of diet quality.”
During the 15-year follow-up, 240 of the 1,865 participants developed dementia. However, the likelihood of developing dementia was reduced in those who adhered to healthier diets.
For people with elevated levels of the Alzheimer’s biomarkers p-tau 217, NFL, and GFAP, higher scores on rEDII were linked to 21% to 29% lower dementia risk.
While the anti-inflammatory diet was beneficial for individuals at high risk, the Mediterranean-style diet seemed to protect brain health only in people with lower baseline biomarker levels.
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MacSweeney explained the potential importance of these findings:
“There is mounting evidence to suggest that what happens in the body can influence inflammatory processes in the brain through the gut-brain-immune axis,” she told MNT.
“It is therefore plausible that individuals who already have Alzheimer’s-related changes may benefit most because reducing inflammatory burden could help slow some of the downstream processes that contribute to cognitive decline and dementia. While we cannot say diet reverses Alzheimer’s pathology, it may help improve resilience and delay the point at which symptoms become clinically apparent,” MacSweeney added.
“One of the hallmarks of Alzheimer’s disease is chronic inflammation within the brain. Increasing evidence suggests that inflammation does not simply occur alongside Alzheimer’s pathology but may actively contribute to disease progression and neuronal damage. An anti-inflammatory diet that is rich in fruit vegetables, nuts, legumes, whole grains and healthy fats may help reduce systemic inflammation throughout the body.”
— Emer MacSweeney
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Describing their findings as “cautiously hopeful,” Mrhar called for further research. She emphasized that the findings “should not be overinterpreted. They do not show that diet can prevent dementia, nor do they prove that changing diet after biomarker changes have emerged will alter disease progression.”
Even if diet cannot prevent or delay the onset of dementia, research suggests that some diets may help keep your brain healthier as you age.
“The same dietary habits that protect the heart appear to benefit the brain,” MacSweeney advised. “Practical recommendations include increasing consumption of leafy green vegetables, berries, oily fish, nuts, seeds, and whole grains, while reducing intake of highly processed foods, sugary drinks, and processed meats. Excess alcohol should also be avoided.”
“Importantly,” she added, “no single food or supplement has been proven to prevent dementia. The overall quality and consistency of dietary habits over many years appear to matter most.”
