Introduction
Dementia is a general term for symptoms that range from memory problems and impaired judgment to a severe loss of language and self-care skills. Alzheimer's disease is the most common form of dementia, accounting for nearly 70% of all cases.
Although dementia symptoms, including Alzheimer’s disease, often occur after age 65, dementia is not a normal part of aging.It is caused by brain cell damage that may be preventable. Most dementia is caused by other diseases, such as central nervous system infections, brain tumors, vascular disease, drug toxicity and poor nutrition. Many of these are lifestyle factors we can control.
Brain anatomy
The brain is made up of three main parts.
- The cerebrum is responsible for thinking, decision-making, language, visual processing, speech, learning and memory.
- The cerebellum coordinates muscles and movements, posture, balance, and actions like walking and talking.
- The brainstem controls heartbeat, blood pressure, body temperature, breathing, thirst, hunger and digestion.
All brain sections can be affected by the degeneration of nerve cells, called neurons. Neurons have branch-like projections creating a neuron forest. Nerve signals travel through the forest, jumping from one tree to another across gaps called synapses.
In Alzheimer’s, neurons, which cannot regenerate, die due to abnormal adhesions that block the flow of nutrients and transmissions. These include beta-amyloid plaques and neurofibrillary tangles.
Plaques are proteins produced by nerve cells and secreted into the fatty membranes around nerve cells. With Alzheimer’s disease, these do not degrade. Instead, they build up and cluster between nerve cells, blocking transmissions.
Tangles are made up of proteins called tau proteins. They are designed to protect the tracks or pathways along which nutrients flow. Tau proteins become twisted, forming tangles inside nerve cells and destroying the pathways. Nutrients cannot reach brain cells, and neurons begin to die, causing the brain to shrink and lose function.
Lifestyle factors
Research has found a relationship between cognitive decline and lifestyle. Factors include high blood pressure and blood sugars, excess abdominal fat, inflammation, a sedentary lifestyle and excess cortisol from stress.
Since the brain uses 20%–25% of the body’s blood and 20% of its oxygen, diseases that reduce circulation (such as high blood pressure, arterial disease, stroke and diabetes) may be major contributors to Alzheimer’s risk.
The food choices we make can increase risk, but they can also be a powerful tool in preventing or slowing the onset of Alzheimer’s and other forms of dementia.
Foods that hurt
Saturated and trans fats
The Women’s Health Study showed that older women with the highest intake of saturated fats had 60%–70% lower brain function scores, equivalent to six years of brain deterioration.
Those with the highest adherence to a low-fat diet, such as the Mediterranean or DASH diets, had the lowest incidence of Alzheimer’s disease.
Sugar
Impaired glucose utilization is associated with the initial stages of cognitive impairment.
A 2008 study published in the Journal of Diabetes Science and Technology refers to Alzheimer’s as Type 3 diabetes, defined as chronic insulin resistance confined to the brain.
Tau proteins are regulated by insulin-like growth factors, which may contribute to the deterioration of these proteins into tangles.
Meat and animal products
Diets high in animal products, saturated fat and cholesterol are associated with an increased risk of dementia, especially Alzheimer’s disease. In observational studies, lower meat consumption was associated with a 53% reduction in risk for Alzheimer’s.
Sirtuins are proteins that regulate cellular health and promote healthy aging. However, glycotoxins — found in cigarettes, high-fat foods, chicken, pork, beef, fish and dairy products — suppress sirtuins, causing higher levels of cognitive decline. Glycotoxins are also produced when meat is fried or grilled at high temperatures.
Vitamin deficiency
Vitamin B12: Cobalamin (B12) is essential for healthy nerve cells and for the production of DNA and RNA. Vitamin B12 deficiency may cause cognitive deficits and dementia. Alzheimer’s patients are likely to have low B12 levels. Doctors may recommend patients take vitamin B12 supplements, either in a chewable form or in a pill placed under the tongue.
Vitamin D: Studies show vitamin D deficiency is associated with the risk of all-cause dementia and Alzheimer’s. Patients with Alzheimer’s and other dementia test low in vitamin D. Supplementing with 800 to 2,000 international units (IU) per day is recommended.
B vitamins: Thiamin, niacin, riboflavin, B6 and folate can help prevent cognitive decline.These B vitamins are found in grains, vegetables, legumes, nuts and seeds. Health experts recommend people get vitamin B from whole food rather than supplements.
Foods that help
Plant-based diets
Diets high in fruits and vegetables and low in meat and fats can protect you from Alzheimer’s. Study participants who adhered to the MIND Diet, a mix of the Mediterranean and DASH diets, reduced their risk for Alzheimer’s by 53%.
Dark fruits
Blueberries and other berries contain anthocyanins and flavonols, powerful antioxidants that help reduce the formation of plaques. Pomegranates contain punicalagin, which reduces inflammation and slows the degeneration of immune cells known as microglia in the central nervous system. Polyphenol antioxidants (found in dark fruit, such as berries) also slow the formation of plaques.
Tomatoes contain lycopene which reduces tumor formation and inflammation in the brain.
Dark leafy greens
Chlorophyll in greens mimics hemoglobin in the blood, amplifying oxygen transport.
High homocysteine levels are independent risk factors for Alzheimer's disease. They are usually the result of low B6 and folate, which can be increased by eating green leafy vegetables daily.
Greens also contain calcium, which helps store and retrieve memories and release neurotransmitters.
Nitric oxide, made from nitrates in raw greens, improves vascular circulation and reduces the risk of arterial blockages, heart attack and stroke.
Green leafy vegetables also contain small amounts of vitamin E, a fat-soluble vitamin believed to play a role in delaying dementia.
Cruciferous vegetables
Researchers found cruciferous vegetables had the largest effect in helping women retain memory. Those who ate 1 1/2 cups per day had 13%–15% lower levels of brain inflammation.
Sulforaphane, a powerful phytochemical found in cruciferous vegetables such as broccoli, bok choy and cabbage, protects against neurodegenerative diseases.
Cruciferous vegetables also include arugula, Brussels sprouts, green and purple cabbage, cauliflower, collard greens, horseradish, kale, kohlrabi, mustard leaves, radish, rutabaga, turnip and watercress.
TIP: Download Dr. Michael Greger’s free Daily Dozen app to your phone to help track your intake of brain-healthy foods.
Omega-3 fatty acids
Omega-3 fats may reduce brain inflammation and prevent cognitive decline, but supplementation with omega-3 fatty acids is not conclusive.
Alpha-linolenic acid, frequently referred to by its acronym ALA, is an essential omega-3 fatty acid found in algae, ground flax, chia seeds, hemp seeds, soy and walnuts. Add 2 tablespoons of seeds or 1 ounce of nuts daily to your diet.
Omega-3 fatty acids docohexaenoic acid (often called DHA) and eicosapentaenoic acid (EPA) are nonessential and can be found in cold-water fish. A 3-ounce portion of tuna, salmon or sardines no more than two times per week is optimal.
Other foods
Spices like saffron, turmeric, ginger, rosemary and cinnamon have anti-inflammatory properties.
Green tea contains EGCG, a flavonoid that protects against the formation of plaques and may impede tau protein tangling.
Other lifestyle factors
Sleep
Alzheimer’s patients often have disrupted sleep patterns. They have trouble staying asleep, lie awake for longer periods and experience disrupted dream stages.
Sleep plays an important role in clearing beta-amyloid from the brain. Sleep deprivation or poor sleep can lead to a build-up of beta-amyloid proteins in the hippocampus and thalamus, regions affected by Alzheimer’s disease. Those who sleep six hours or fewer per night are more likely to develop dementia later in life.
Exercise
Older adults who regularly exercise at moderate levels have significantly lower rates of dementia and Alzheimer’s. Exercise improves blood flow to the brain and lowers cholesterol, reducing the risk of heart attack and stroke.
Experts recommend three to six hours of exercise per week or 30 minutes per day of moderate-intensity exercise like walking or bicycling. Exercise can also help older adults to socialize.
Socialization
Our brains are designed to be stimulated by social interactions and relationships. A 2008 study found that older women with larger social networks were less likely to develop Alzheimer’s or dementia than older women with smaller social networks. A 2011 study showed that being social can reduce dementia risk by 70%.
A 2016 study found older adults derive social and emotional benefits from playing digital games.
Brain exercises
The ACTIVE study (Advanced Cognitive Training for Independent and Vital Elderly) found that participants who played brain-training games had a 29% reduction in dementia risk after 10 years of follow-up.
Brain training can include solving visual puzzles, written riddles and learning a new dance or language.
For example, try the Stroop Test. As quickly as possible, read aloud the COLOR you see, not the word you read.
Best practices
- Adopt a MIND Diet low in fat and cholesterol and high in fruits, vegetables, nuts, seeds, legumes and intact grains. Include cruciferous and raw greens daily.
- Limit consumption of animal products to no more than twice a week.
- To flavor foods, use herbs and such spices as turmeric, rosemary, cinnamon, saffron and ginger instead of salt.
- Drink green tea daily in place of sweetened beverages.
- Add a dietary supplement for vitamins B12 and D.
- Aim for seven to nine hours of restful sleep per night.
- Get 30 minutes of physical activity and 30 minutes of social interactions daily.
- Use brain-training games to keep your brain active.
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