Dementia Risk Lower With Anti-Inflammatory Diet Even With Alzheimer’s Biomarkers

People with Alzheimer’s disease biomarkers who followed a dietary pattern with less inflammatory potential had a lower risk of developing dementia, a longitudinal study in Sweden showed.

Over 8 years, the study followed a cohort of nearly 1,900 older adults who had baseline blood measurements of phosphorylated tau-217 (p-tau217), neurofilament light chain (NfL), or glial fibrillary acidic protein (GFAP).

Each z-score increase in adherence to an anti-inflammatory eating pattern, based on reversed Empirical Dietary Inflammatory Index scores, was associated with lower dementia risk, according to Anja Mrhar, MSc, of Karolinska Institutet and Stockholm University, and colleagues.

Participants with elevated p-tau217 had a 29% lower risk of dementia (HR 0.71, 95% CI 0.58-0.88) if they followed a lower inflammatory eating pattern, the researchers wrote in JAMA Network Open. Those with elevated NfL had a 21% lower risk (HR 0.79, 95% CI 0.66-0.95), and those with elevated GFAP had a 27% lower risk (HR 0.73, 95% CI 0.60-0.89).

Older adults with elevated p-tau217 and higher adherence to a lower-inflammatory diet also lived nearly 1 year longer without dementia (0.89 years, 95% CI 0.29-1.50 years) compared with those with lower adherence.

Associations between lower dementia risk and two other eating patterns — the Alternate Mediterranean Diet and the Alternative Healthy Eating Index — were generally found only among people with lower biomarker levels, Mrhar and co-authors said. Findings were similar for overall dementia and Alzheimer’s disease dementia.

Many studies have tied Mediterranean diets and other healthy eating patterns to better brain health and less dementia risk. “However, it’s been less clear whether diet quality is still relevant among people who already show biological signs of increased dementia risk,” Mrhar told MedPage Today.

“In this study, we examined dementia risk in relation to diet quality among older adults with different levels of blood-based biomarkers,” she said. “These biomarkers can reflect Alzheimer’s disease-related pathology, neuronal injury, and glial activation — biological processes linked to dementia risk. Such changes may begin years before noticeable symptoms appear, but not everyone with these biomarker changes will develop dementia.”

All three eating patterns evaluated in the study focused on different dimensions of diet but encouraged vegetable, fruit, nut, and whole grain consumption and discouraged consumption of red and processed meats and sugar-sweetened beverages, the researchers noted.

The dietary inflammatory index “is not simply another version of general healthy eating guidelines,” Mrhar pointed out. “It is an empirically derived measure based on how patterns of food intake relate to inflammatory markers in previous research,” she said. “Therefore, our findings should not be interpreted as identifying one specific anti-inflammatory diet or a simple list of foods that would reduce dementia risk.”

Identifying secondary prevention strategies for dementia is increasingly important in an era where blood-based Alzheimer’s tests are becoming more accurate and widely accessible, noted Sokratis Charisis, MD, of Harvard Medical School in Boston, and Nikolaos Scarmeas, MD, MS, PhD, of the National and Kapodistrian University of Athens in Greece.

The results of this study “represent an important step in this direction, laying the groundwork for future clinical trials to test certain dietary interventions with robust observational evidence of protective associations, such as the Mediterranean and anti-inflammatory diets, as effective strategies for cognitive decline and dementia prevention,” Charisis and Scarmeas wrote in an accompanying editorial.

Mrhar and colleagues followed 1,865 participants from the Swedish National Study on Aging and Care in Kungsholmen without dementia at baseline. Participants had a mean age of 70.5 years, and 60.3% were women. Study visits were conducted at baseline, 3 years, and 6 years.

The researchers assessed diet quality using data from a 98-item food frequency questionnaire to evaluate repeated adherence to three dietary patterns: the Alternate Mediterranean Diet, the Alternative Healthy Eating Index, and the reversed Empirical Dietary Inflammatory Index. Cumulative average adherence scores were standardized using z scores, with higher scores reflecting higher-quality diets.

Dementia was diagnosed by two independent physicians based on examinations, medical records, and death certificates. The mean follow-up duration was 8.4 years. Over that time, 240 participants developed dementia.

Study limitations included the use of self-reported data about food intake and several adjustment variables, the researchers acknowledged. Biomarkers were measured in serum, not plasma or cerebrospinal fluid.

“Overall, the findings do not prove that diet prevents dementia,” Mrhar emphasized. “Rather, they suggest that diet quality may remain relevant for dementia risk even when early biological signs of increased risk are already detectable, and that different aspects of diet quality may matter in different ways, depending on a person’s biological risk profile.”