Right now the world is experiencing an epidemic that is projected to get much, much worse. It's an epidemic of dementia, affecting 40 million people — and millions more of their caregivers — staggering numbers that will likely triple by 2050.
Dementia is a progressive deterioration of brain functioning associated with aging. While there are different causes, the most common — Alzheimer's and vascular dementias — are now thought to be closely related.
How is heart health related to cognitive health?
We have long known that the diseases and conditions that clog the arteries of the heart also clog the arteries of the rest of the body, including the brain. It all boils down to damage of the arteries, the blood vessels that are critical for blood flow and oxygen delivery to the organs. Arterial damage leads to arterial blockages, which leads to heart disease and heart attacks, strokes, peripheral vascular disease, and vascular dementia.
Meanwhile, Alzheimer's disease used to be thought of as a different process, because the brains of people with Alzheimer's seemed to be full of tangled tube-shaped proteins (neurofibrillary tangles). However, more and more research is linking Alzheimer's dementia to the same risk factors that cause heart disease, strokes, peripheral vascular disease, and vascular dementias: these risk factors are obesity, high blood pressure, high cholesterol, and diabetes.
The evidence is substantial: studies show that people with these conditions are significantly more likely to develop Alzheimer's disease. Meanwhile, studies also show that people with Alzheimer's disease have significantly reduced brain blood flow, and autopsy studies show that brains affected by Alzheimer's can also have significant vascular damage.
Researchers are now focusing on why this is — what is the connection? It appears that good brain blood flow is key for clearing those tubular proteins that can accumulate and become tangled in the brains of Alzheimer's patients, and so one solid hypothesis is that anything that reduces that blood flow can increase the risk for Alzheimer's, and conversely, anything that increases blood flow can reduce the risk for Alzheimer's.
Healthy heart behaviors can lower your risk of dementia
And it is true that exercise lowers the risk of dementia, even Alzheimer's. Studies show that people who exercise more are less likely to develop dementia of any kind, and this stands even for adults with mild cognitive impairment. There is also substantial research evidence showing that eating a Mediterranean-style diet high in fruits, vegetables, whole grains, healthy fats, and seafood is associated with a significantly lower risk of cognitive decline and dementia.
The take-home message here is, even if someone has a family history of dementia, particularly Alzheimer's dementia, and even if they already have mild cognitive impairment (forgetfulness, confusion), they can still reduce their risk of developing dementia by simply living a heart-healthy lifestyle. That means a Mediterranean-style diet with 4 or 5 servings of fruits and veggies daily, and 150 minutes per week of activity. Lifestyle factors that help to reduce stress can also help: enough hours of good sleep, positive relationships, and social engagement have been shown to protect cognition.
Association of obesity, diabetes, and hypertension with cognitive impairment in older age. Clinical Epidemiology, July 25, 2018.
Vascular and metabolic factors in Alzheimer's diseases and related dementias. Cellular and Molecular Neurobiology, March 2016.
Defining the relationship between hypertension, cognitive decline, and dementia: a review. Current Hypertension Reoprts, March 2017.
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