Mediterranean, MIND Diets May Slow Down Alzheimer Disease Pathology

Consuming a healthy diet, such as the Mediterranean diet, may be associated with less Alzheimer disease (AD) pathology and improved cognition, according to findings from an observational study published in Neurology.

The Mediterranean-DASH (Dietary Approaches to Stop Hypertension) Intervention for Neurodegenerative Delay (MIND) diet, the Mediterranean diet, and the DASH diet, are linked to a reduced risk for AD, slower decline in cognition, less functional disability, and improved cognition independent of AD. These healthy diets comprise plant-based eating patterns that are rich in nutrients and bioactive compounds, contain antioxidant properties, and are essential for brain health. High sugar and high fat diets such as the Western diet, on the other hand, are linked to poor cognition.

For the study, researchers sought to evaluate the association of the MIND and Mediterranean diet scores and different food groups with beta-amyloid load, phosphorylated tau tangles, and global AD pathology in autopsied participants from the Rush Memory and Aging Project (MAP).

Researchers evaluated diet adherence by scoring patients from 0-55 total points for the Mediterranean diet and 0-15 total points for the MIND diet. A higher score indicated a greater adherence to the diets.

In secondary analyses, the models were adjusted for the following variables:

• Lifestyle factors, including physical activity and smoking, as well as vascular disease burden
• Body mass index (BMI), which could serve either as a mediator or a confounder in the model, as it is a clinical consequence of AD and is also linked to an individual’s diet

The final sample comprised a total of 581 participants (mean age, 84.2; 73% women) who underwent dietary assessment before death.

For the Mediterranean diet, the group with the highest adherence had an average score was 35 points; the group with the lowest adherence had an average score of 26 points. For the MIND diet, the highest adherence group had an average score of 9 points and the lowest group had an average score of 6 points.

Researchers found that dietary patterns were statistically significantly associated with lower global AD pathology (MIND diet: P =.035; Mediterranean diet:
P =.039), as well as with specifically less beta-amyloid load (MIND diet: P =.050; Mediterranean diet: P =.004).

When the models were adjusted for the variables of vascular disease burden, physical activity, and smoking, significant associations with global AD pathology were maintained with both the MIND diet (P =.047) and the Mediterranean diet (P =.027). Regarding beta-amyloid load, however, only the Mediterranean diet (P =.007), not the MIND diet (P =.115), demonstrated a significant association.

Based on findings from a secondary analysis that was controlled with respect to BMI, the significant association of the MIND diet with global AD pathology was retained
(P =.037); however, beta-amyloid was reduced (P =.055). In contrast, regarding the Mediterranean diet, the association with global AD pathology was weakened (P =.058) but was retained for beta-amyloid load (P =.005).

When the associations of selected food groups with AD pathology outcomes were investigated, participants in the highest tertile of green leafy vegetable intake exhibited statistically significantly lower global AD pathology (P =.0038) than those in the lowest  tertile.

A limitation of the study included the lack of generalizability for younger adults or a more diverse ethnic populations due to study participants being mainly White, non-Hispanic, older adults.

“Future diet studies should investigate other potential mechanisms for protective effects on the brain, including the direct effects of diet on AD pathology, and should examine potential mechanisms and pathways via vascular and other pathologies as well as the role of inflammation,” the researchers noted. “Studies should also investigate person-specific factors and capitalize on emerging in-vivo biomarkers and human brain tissue when available,” they concluded.