Scientists have identified a dietary pattern that may significantly lower the risk of dementia and slow cognitive decline. A study published in JAMA Neurology found that closely following certain healthy eating plans was associated with better brain function and slower cognitive aging compared to other popular diets.
The research, led by experts at the Harvard TH Chan School of Public Health, analysed health data from more than 159,000 participants with an average age of 44. Researchers examined six widely followed dietary patterns:
- Alternate Healthy Eating Index 2010
- The DASH diet
- The Healthful Plant-Based Diet Index
- Planetary Health Diet Index
- Reversed empirical dietary indices for hyperinsulinemia
- Reversed empirical dietary indices for inflammatory patterns
“Few studies have systematically compared multiple dietary patterns for cognitive health within the same populations,” said Kjetil Bjornevik, assistant professor in the Departments of Nutrition and Epidemiology at Harvard and the study’s senior author. “By analysing six distinct approaches using the same participants and methods, we were able to identify which showed the most consistent associations.”
Which diet performed best?
Among the diets studied, the DASH diet showed the strongest and most consistent links to reduced subjective cognitive decline and better objectively measured cognitive performance. Specific food groups — particularly vegetables, fish, and moderate wine consumption — were associated with improved brain health. In contrast, red and processed meats, fried foods, and sugary drinks were linked to poorer outcomes.
“These findings help pinpoint which dietary components may be driving the protective effects,” Bjornevik noted.
What is the DASH diet?
The DASH diet (Dietary Approaches to Stop Hypertension) was originally developed to reduce high blood pressure. However, its benefits extend well beyond heart health. Because cardiovascular health is closely connected to brain function, experts believe the DASH diet may also help reduce the risk of dementia.
High blood pressure, diabetes, obesity, and elevated cholesterol are major risk factors for cognitive decline. The DASH diet addresses all of these, making it a powerful preventive strategy.
How does DASH help protect the brain?
Research suggests the diet may lower dementia risk by:
- Reducing blood pressure
- Decreasing inflammation
- Improving blood flow to the brain
- Supporting overall vascular health
- Stabilising blood sugar levels
Since poor circulation can gradually damage brain cells, maintaining strong vascular health is key to protecting against conditions such as Alzheimer’s disease.
What to eat on the DASH diet
The DASH plan emphasises nutrient-dense, whole foods, including:
- Leafy green vegetables
- Fruits, particularly berries
- Whole grains such as oats and brown rice
- Low-fat dairy products
- Lean proteins like poultry and fish
- Legumes and beans
- Nuts and seeds
- Healthy fats, especially olive oil
Overall, the findings reinforce the idea that what benefits the heart also benefits the brain — and that long-term dietary habits can play a crucial role in protecting cognitive health.
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