A healthier diet — particularly one with lower inflammatory potential — was associated with a lower risk for dementia among older adults with Alzheimer’s disease (AD) pathology and broader neurobiological risk. 

In a prospective, population-based cohort study, investigators followed 1865 older adults for up to 15 years and found greater adherence to a lower-inflammatory dietary pattern was associated with up to a 29% lower risk of developing dementia among those with elevated AD biomarkers.

“The single most important message is that diet quality may still be relevant for dementia risk, even among older adults who already have blood-based biological markers linked to increased risk, including AD-related pathology,” study investigator Anja Mrhar, MSc, Aging Research Center, Karolinska Institutet and Stockholm University, Sweden, told Medscape Medical News. 

However, Mrhar cautioned that these observational findings should not be interpreted to mean that diet can prevent dementia. “Rather, the findings suggest that lifestyle factors such as diet may remain important to consider even when early disease-related biological changes are already detectable,” she said. 

The study was published online June 25 in JAMA Network Open. 

First Study of Its Kind

Higher diet quality has been linked to a reduced incidence of dementia. The researchers noted that this is the first study to examine whether diet quality modifies dementia risk across strata of biological risk defined by blood biomarkers of AD and broader neurodegeneration.

They analyzed data from 1865 dementia-free adults aged 60 and older (mean age at baseline, 70 years; 60% women) from the population-based Swedish National study on Aging and Care in Kungsholmen cohort. 

Over 6 years, they repeatedly assessed adherence to three dietary patterns: the Alternate Mediterranean Diet (AMED), Alternative Healthy Eating Index (AHEI), and the reversed Empirical Dietary Inflammatory Index (rEDII). 

Risk for dementia was analyzed in relation to blood concentrations of p-tau217 (a marker of AD pathology), neurofilament light chain (NFL; a marker of neuronal injury), and glial fibrillary acidic protein (GFAP; indicative of inflammation-related glial processes).

During a mean follow-up of 8.4 years, 240 participants developed dementia. In adults with higher biomarker levels, higher adherence to healthier dietary patterns was associated with a lower dementia risk, although several comparisons were not significant, the authors noted.

The lower-inflammatory rEDII dietary pattern showed the most consistent association with lower dementia risk. With each 1-z-score increase in adherence to this diet pattern, dementia risk was 29% lower in those with elevated p-tau217 (hazard ratio [HR], 0.71), 21% lower in those with elevated NFL (HR, 0.79), and 27% lower in those with elevated GFAP (HR, 0.73).

In addition, over a 10-year period, older adults with elevated p-tau217 and higher adherence to the lower-inflammatory dietary pattern lived nearly 1 year longer without dementia compared with those with lower adherence, Mrhar told Medscape. 

Associations between higher adherence to the lower-inflammatory rEDII dietary pattern and reduced dementia risk were not significant among adults with lower biomarker levels. The AMED and AHEI patterns were generally associated with lower dementia risk only among participants with lower biomarker levels.

Too Soon for Dietary Recommendations

Mrhar noted that a dietary pattern with lower inflammatory potential reflects a combination of food choices that has been linked in previous research to lower levels of inflammatory markers in the body. It is not defined by a single food or nutrient, but by the overall pattern of intake.

“Broadly, such patterns tend to include more foods often considered part of healthy diets, such as vegetables, fruits, whole grains, legumes, nuts and fish, and lower intake of foods commonly linked to poorer cardiometabolic or inflammatory profiles, such as processed meats, refined grains, and sugar-sweetened beverages,” she said.

She noted, however, that the inflammatory dietary index used in the study is not identical to standard healthy eating guidelines, and it captures a specific inflammation-related dimension of diet quality.

“We would be cautious about recommending a lower-inflammatory diet specifically as a dementia-prevention strategy for older adults with AD pathology based on our study alone. Clinical recommendations should be based on the broader evidence base, and intervention studies are needed to determine whether changing diet can reduce dementia risk in this group,” Mrhar said. 

She added that the findings suggest that although Alzheimer’s-related biomarkers identify people at higher risk for dementia, diet quality — especially adherence to a less inflammatory dietary pattern — may still play a role in delaying disease progression. 

“Overall, we would describe the findings as cautiously hopeful. Biological signs linked to dementia indicate increased risk, but our results suggest that diet quality — particularly the inflammatory potential of the diet — may still be relevant even when such early biological changes are already present,” Mrhar said. 

An Important Advance

The findings “align well with the growing body of observational evidence linking dietary habits to cognitive health” and the integration of blood-based biomarkers represents “an important” advance over previous studies, wrote Sokratis Charisis, MD, of Harvard Medical School in Boston, and Nikolaos Scarmeas, MD, MS, PhD, of the National and Kapodistrian University of Athens Medical School in Greece, in a linked editorial. 

They said the findings highlight the potential relevance of healthy dietary habits as secondary prevention strategies, which is becoming “increasingly important in an era where blood-based AD diagnostics become progressively more accurate and widely accessible.”

They added that the study represents “an important step in this direction, laying the groundwork for future clinical trials to evaluate dietary interventions with observational evidence of protective associations, such as Mediterranean and anti-inflammatory diets, as strategies for cognitive decline and dementia prevention.”

The study had no commercial funding. None of the authors reported conflicts of interest. Charisis had no disclosures. Scarmeas reported receiving grants to his institution from Novo Nordisk and Bristol Myers Squibb and data safety monitoring board membership for PRInnovation GmbH PRimus AD.