One of the best ways to protect your brain from Alzheimer’s disease (AD) and dementia may be to protect your blood vessels. Abundant scientific evidence has made it clear that the brain is highly dependent on a plentiful supply of oxygen and nutrient-rich blood, and ensuring the integrity of the system that delivers that blood can help keep brain cells healthy.
“Healthy blood vessels and capillaries are critical to proper brain function,” says Jack Rogers, PhD, Director of the Neurochemistry Laboratory in the Department of Psychiatry at Massachusetts General Hospital (MGH). “To maximize brain health as you age, it is important to avoid factors that may contribute to weakening, narrowing, or blockage of cerebral blood vessels—changes that can trigger small strokes and hemorrhages, destroy areas of brain tissue, lead to the formation of toxic proteins in the brain, and contribute to cognitive decline.”
Prime cause of dementia
A review paper published in October 2012 in the journal Alzheimer’s Disease and Associated Disorders summed up decades of research into dementia and singled out six risk factors for vascular disease, which, if avoided or managed, might dramatically reduce the incidence of common forms of dementia. This paper argues that focusing on these risk factors would not only help prevent heart attacks and strokes, but also protect the blood vessels of the brain from deterioration that may lead to reduced cerebral blood flow and cognitive decline.
“The breakdown of the cerebral vasculature is an aspect of vascular dementia (VaD), in which a reduction or blockage of blood flow to small regions of the brain eventually kills brain cells and impairs cognition,” explains Dr. Rogers. “It is also an aspect of cerebral amyloid angiopathy (CAA), a condition associated with AD in which toxic beta-amyloid proteins build up in blood vessel walls. CAA weakens blood vessels, causing them to leak into surrounding tissue and contribute to the accumulation in the brain of beta-amyloid plaques, a hallmark of AD. In many cases, people with dementia may have a combination of VaD and accumulations of beta-amyloid plaque characteristic of AD—a condition called mixed dementia.
“The risk factors mentioned in the review can lead to such destructive changes as oxidative damage and injury to blood vessels, impaired circulation, blockages caused by blood clots or other materials, and more. But the good news is that, in most cases, they can be prevented or managed with lifestyle changes and proper medical care.”
Risk factors to avoid
Prevention programs that focus on the most important vascular risk factors would go a long way toward helping reduce the risk of vascular dementia and mixed dementia, experts say. The risk factors are:
Hypertension (high blood pressure): Managing your blood pressure can help you avoid strokes and heart disease, maintain elasticity of brain blood vessels, prevent reductions in cerebral blood flow that alter the functioning of blood vessels in your brain and damage or kill brain cells, and reduce your risk for mild cognitive impairment (MCI), which is associated with greater risk for dementia. Research suggests blood pressure control may also reduce your risk for neuroinflammation, dysfunction of the blood-brain barrier, and increases in beta-amyloid in the brain. Suggestion: Check your blood pressure regularly, and if you have hypertension, make lifestyle changes such as getting regular exercise, improving your diet, reducing salt intake, and/or taking medications as directed by your doctor.
Hyperlipidemia (high blood cholesterol): Cholesterol helps stabilize brain cell membranes and is an important component of the protective myelin sheaths that coat the axons linking brain cells, but elevated levels of these fats in the blood may lead to a build-up of waxy deposits on the inside of blood vessels. These deposits not only narrow the vessels and reduce circulation to the brain, they may also break free and lodge upstream in the brain capillaries, blocking blood flow and destroying areas of brain tissue. A 2011 study of Japanese men found that individuals who had the highest total cholesterol levels in mid- to late life were seven times more likely to have beta-amyloid plaques in their brains by the time they died than those with the lowest levels. (The American Heart Association recommends total cholesterol levels of 200 mg/dL or below.) Suggestion: Have your blood cholesterol levels checked regularly. High total blood cholesterol calls for lifestyle changes such as losing weight, increasing physical activity, and adopting a healthier diet and/or taking medications, if your doctor recommends them.
Smoking: Quitting smoking is a high priority if you wish to maintain healthy blood vessels. The carbon monoxide in cigarette smoke damages the inner lining of blood vessels, making the deposit of fats and plaque more likely, and the nicotine promotes narrowing and hardening of the blood vessels, leading to reduced blood flow and blockages. Smoking is a major cause of stroke. Suggestion: If you smoke, quit. If you can’t quit on your own, see a doctor. Avoid secondhand smoke as much as possible.
Diabetes: Preventing or controlling diabetes can protect the brain’s blood vessels from damage associated with high blood sugar and insulin levels, such as vascular lesions, chronic inflammation that impairs blood flow to the brain, damage to capillaries, and atherosclerosis (or “hardening of the arteries”). People with diabetes have twice the normal risk for AD and a significantly higher-than-normal risk for brain-damaging stroke. Suggestion: To prevent diabetes, watch your weight, exercise regularly, and eat a healthy diet that replaces sweets, sodas, processed meats, and other junk foods with more nutritious fare. Have regular checkups that include tests of blood sugar and insulin levels. Individuals with diabetes should work closely with their doctors to maintain control of their blood sugar, and to address any other conditions associated with their diabetes that might negatively affect the brain.
Poor nutrition and inactivity: Physical inactivity and unhealthy dietary practices are serious risk factors for dementia. Suggestion: Maintain a regular exercise routine (at least 30 minutes a day, five days a week or more) and eat a nutritious, low-fat diet with plenty of fresh fruits, vegetables, whole grains, lean protein, nuts, beans and fish (see Eating Mediterranean Style on Page 6).
Hyperhomocysteinemia (high levels of homocysteine): Excessively high blood levels of homocysteine, an amino acid, have been linked to inflammation of blood vessels, and greater risk of blood clots, stroke, heart attack and dementia-type disorders. Eating abundant amounts of foods containing vitamins B6, B12, and folate (vitamin B9)—such as fish, lean meats and poultry, dark green leafy vegetables, potatoes and beans—can help protect against hyperhomocysteinemia, as can vitamin B supplements in some cases. Suggestion: Eat a diet with plenty of vitamin B. Have your homocysteine levels checked regularly, and if they are high, ask your doctor whether supplementation with folate and/or other B vitamins is advisable.