Nutrition & Dementia (AD)
✔An Updated Review of Dietary Patterns and their Effects on Alzheimer's Disease and Related Dementias, linking Nutrition to Neuroscience.
IMAGE DESCRIPTION »
Dietary Patterns with varying degrees of influence on Alzheimer's Disease and Related Dementias. In the left side is shown how A long-term and consistent Healthy Diet and Lifestyle are associated with a Lower predisposition to Neuroinflammation and Insulin Resistance (IR) associated with Aging. These effects are enhanced by adding Healthy Lifestyles and Exercise to the Diet, leading to better health, quality of life, and Improved Cognitive Function.
On the right side of the image, several Dietary Patterns are exemplified that may improve or Decrease AD and other related dementias (ADRD) through different mechanisms, which may be attributed to the effects of the diverse Patterns or Nutrients existing in each diet.
SUMMARY
Nutrition & Dementia (AD): A Neuroscience Approach
An Updated Review of Dietary Patterns and their Effects on Alzheimer's Disease, and Related Dementias, Linking Nutrition to Neuroscience.
Background
- Current research indicates over 55 Million people Worldwide are suffering from Dementia, considered one of the most prevalent illnesses among Older Adults.
- As innumerable studies about Alzheimer’s Disease (AD) have established, there is currently No Cure or Treatment for AD. Prevention is therefore crucial, and research has been directed towards identifying the Best Dietary and Lifestyle Patterns, to find the most effective Preventive Interventions against ADRD.
- The most studied Dietary Patterns included in this review are the Mediterranean Diet, DASH, MIND, and Ketogenic Diet, as well as a New Combination called the Modified Mediterranean-Ketogenic Diet.
- This review compiles clinical evidence from research studies on the association between these dietary patterns and their Beneficial Effects on Alzheimer's Disease and Related Dementias (ADRD).
- Studies have shown that these benefits are due to the Direct Effects of specific dietary components (Nutrients) acting on the Brain. In addition, it is also due to Indirect Effects on Risk Factors for Alzheimer's Disease (ADRD), such as Diabetes, Obesity, and Cardiovascular Disease.
Alzheimer's Disease (AD)
Alzheimer's Disease (AD) is the most common form of Dementia, characterized by memory loss and progressive Neurodegeneration.
- It is projected that by 2030, 8.2 million people will be diagnosed with AD, and this number is expected to increase to 14 million by 2060 in the US. Centers for Disease Control and Prevention – CDC 2023.
- Alzheimer's Disease (AD) begins with structural changes in the Brain 20 years before Clinical Manifestations. Brain Atrophy develops over time, with the Hippocampus and Neocortex being the regions affected Earliest.
- This Progressive Neurodegeneration affects the ability to respond to the environment and engage in activities of daily living, leading the patient to an increasing level of disability until the end.
- Research has shown that Non-Modifiable Factors, such as genetics, gender, and age, and Modifiable Factors, such as education, physical activity, sleep, diet, smoking, and alcohol use can influence AD.
- The lack of a cure or effective treatment available for AD has led to a growing interest in preventive actions and interventions aimed at promoting Healthy Brain Aging.
One-third of Alzheimer's Disease (AD) cases involve Modifiable Risk Factors that can be prevented through Dietary and Lifestyle Interventions.
- Regular Physical Activity and a Healthy Diet can Improve Cognitive Function, reducing the risk of developing Alzheimer’s Disease. Indeed, emerging evidence supports the relationship between Diet and ADRD Development.
- Likewise, research has already identified several Dietary Patterns associated with slower Cognitive Decline and a Lower Risk of ADRD, although the mechanisms underlying these effects remain unclear.
Impact of Specific Dietary Patterns on ADRD Progression
The American Dietary Guidelines recommend a Diet Centered on Plant-based Foods while limiting red meat, sodium, saturated fat, sugar, and highly processed foods.
- This Plant-based Dietary Pattern could play a crucial role, both directly and indirectly, in cognitive health and the development of dementia.
Specific Nutrients (vitamins, antioxidants, etc.) in this plant-based dietary pattern, Directly Affect Cognitive Health through their antioxidant, anti-inflammatory, and endothelial functions on the Brain.
- Furthermore, as these nutrients are consumed as part of a Dietary Pattern, they also have a Beneficial Indirect Effect on Cognitive Health, by acting on Risk Factors for ADRD, such as Diabetes, Dyslipidemia, Hypertension, and Obesity (among others).
- The present study reviewed Dietary Patterns with evidence of important effects on the progression of Alzheimer's Disease and Related Dementias (ADRD).
This Review found relatively strong evidence that adherence to the MedD, DASH, MIND, and MMKD diets may Reduce the Risk of Developing ADRD and slow the rate of Decline.
Impact of Mediterranean Diet on ADRD Progression
- The Mediterranean Diet (MD) consists of nutrient-rich foods. It is characterized by a high consumption of olive oil, unrefined cereals, fruits, and vegetables, a moderate to high intake of fish, and a low consumption of red meat.
It is considered the ´Best Diet to slow the Progression of ADRD´ due to its association with a Lower Risk of Conversion from Mild Cognitive Impairment (MCI) to Dementia, a lower incidence of dementia, with better maintenance of brain health and Lower Cognitive Decline.
- The Mediterranean Diet (MedD) acts through various mechanisms, including its anti-inflammatory, antioxidant, and lipid-lowering actions, as well as its favorable impact on Cardiovascular Risk Factors.
- The MedD has demonstrated the potential to reduce the incidence of ADRD through its beneficial effects on blood pressure, cerebral blood flow, and the preservation of brain tissue microstructures (Hippocampus).
- As mentioned above, other Dietary Patterns with Evidence of important effects on the Progression of Alzheimer's Disease (ADRD) were also assessed in this review:
The DASH Diet showed only modest cognitive benefits, especially when combined with weight control or aerobic exercise.
The MIND Diet, blending Mediterranean and DASH elements, has shown consistency in Improving Cognitive Function and Reducing Alzheimer’s Disease Risk.
The Ketogenic Diet, characterized by high fat and low carbohydrate intake, has shown significant short-term cognitive improvements but presents challenges in long-term adherence due to its restrictiveness.
The Modified Mediterranean-Ketogenic Diet (MMKD), combining Mediterranean and Ketogenic principles, has shown preliminary success in improving cognitive function but requires further large-scale studies.
The Vegetarian Diet, rich in vegetables, fruits, and whole grains, shows potential to reduce cognitive decline, though careful management of protein and vitamin intake is necessary.
The Vegan Diet, excluding all animal products, offers high fiber and vitamins that may slow AD progression, but long-term adherence risks causing nutrient deficiencies that affect cognitive health.
The reviewed Dietary Patterns above have been shown to slow the Progression of Alzheimer's Disease (ADRD) and may also play a Preventive Role.
- However, it is crucial to determine when to begin the consumption or adhering to these Dietary Patterns, as ADRD symptoms can manifest decades after the onset of the first changes in Brain structure.
- Some researchers suggest the adequate time to start implementing Diet Interventions is around 50-60 years old or earlier, and Recommend Dietary Interventions last 4-8 years to reach the accumulated long-term adherence effects.
CONCLUSION
- The primary aim of this review is to evaluate current Evidence on Dietary Patterns and their effects on ADRD Risk and Progression.
- Despite discrepancies in the reported benefits among studies examining dietary patterns, the review has shown there is relatively Strong Evidence of Brain Benefits Against ADRD.
- Adherence to the MedD, DASH, MIND, and MMKD Diets has the Greatest Efficacy for their Neuroprotective Benefits. In addition, they can Reduce the Risk of Developing ADRD and slow the rate of Cognitive Decline.
- However, the precise pathways underlying and mediating the Preventive and Ameliorative effects of these Diets on ADRD remain unclear, and further research is required.
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Sources » Ellouze, I. et al. Dietary Patterns and Alzheimer’s Disease: An Updated Review Linking Nutrition to Neuroscience. Nutrients 2023, 15, 3204. https://doi.org/10.3390/nu15143204
Very informative and insightful. I have written a similar article about the "Gut-Brain axis". Please have a look : https://vishakhvs.substack.com/p/second-brain-sonata-gut-microbiomes?r=31kya5