Can a Healthy Heart Protect Against Dementia?
Heart Disease And Dementia Share Risk Factors
Becoming a little forgetful is a normal part of aging. But if someone has large memory gaps, often wanders and becomes lost, or their behavior changes drastically, becoming violent, aggressive or even more passive, those could be signs of dementia.
“Dementia is an umbrella term. There are different types, but they manifest the same,” says Reynaria Pitts, MD, a cardiologist with North Suburban Medical Center in Thornton, Colorado.
Each type of dementia—which includes Alzheimer’s disease, vascular dementia, Lewy body dementia and others—has varying causes. While all forms of dementia affect the brain, Dr. Pitts says that some forms may originate in the heart. High blood pressure and atherosclerosis may contribute to vascular dementia, while there’s an association—and, according to Pitts, a genetic link—between Alzheimer’s and cholesterol.
Alzheimer’s Disease And Cholesterol Levels
Alzheimer’s disease is the most common form of dementia in older people. It’s characterized by clumps in the brain called amyloid plaques, tangles of tau protein fibers and a loss of connection between brain cells. It is progressive and incurable.
How is it connected to the heart? Cholesterol. A 2016 meta-analysis looked at 17 studies between 1996 and 2014, encompassing more than 23,000 people, and determined that the data suggests having high total cholesterol in middle-age increased the risk of Alzheimer’s later in life.
Cholesterol and Alzheimer’s disease share a genetic link. Cholesterol is carried through the bloodstream by molecules called lipoproteins. One of the molecular building blocks of lipoproteins are controlled by a gene called APOE. One version of this gene is known to increase the risk of Alzheimer’s, though researchers haven’t figured out exactly how.
“If someone comes in with high cholesterol and we’re figuring out why, we can check the genetic markers. If we find that they have this modified gene, this increases the risk of Alzheimer’s greatly,” says Pitts.
There are other ways that heart disease can cause dementia, says Pitts. “Heart failure. If heart function is low, the brain isn’t getting enough blood. That can cause some cognitive dysfunction,” she says, though she adds that it might not be severe enough to truly call it dementia.
Vascular Dementia And Hypertension
It’s not just cholesterol that’s linked to dementia. Risk factors for heart disease like high blood pressure, atherosclerosis, smoking and diabetes can cause vascular dementia, the second-most common type of dementia next to Alzheimer’s in people over the age of 65. Vascular dementia is caused by small strokes. Its symptoms are very similar to Alzheimer’s and it can be hard to tell the difference between the two.
“Sometimes it’s obvious, though,” says Pitts. “If a patient has long-standing hypertension, it’s obvious that it’s vascular dementia. On the other hand, with a patient who has no history of hypertension and is even on the lower scale of blood pressure, but has dementia, you start leaning toward an Alzheimer’s diagnosis.”
Genetic Testing to Determine Risks
Though it may be possible to slow the symptoms of or avoid some forms of dementia, like vascular dementia by treating the root causes, there’s no way to stop other types like Alzheimer’s. Some genetic tests can tell you if you’re likely to develop dementia.
“If you are a patient who’s at risk, knowing that depends on patient preference,” Pitts says. “Knowing you may develop dementia might lead you to worry over something that’s out of your control.”
On the other hand, you may want to know so you can prepare for the future, says Pitts. “You may want to lower some risk factors that can worsen dementia’s clinical manifestation. If someone has high cholesterol, high blood pressure or diabetes, they may be more inclined to control risk factors,” she says.
“The other issue is what it means for family members,” Pitts adds. “Giving family members genetic tests for their risk of dementia is usually not recommended, but if a patient knows he or she is at risk, it could have consequences for their children or other family members and may motivate the family to lower their own risks.”