Becoming a little forgetful is a typical 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.
There are different types of dementia, and each type may have different causes. While all forms of dementia affect the brain, Dr. Pitts says that some forms may originate in the heart. High blood pressure and hardening of the arteries (atherosclerosis) may contribute to vascular dementia. And, there's an association and genetic link between Alzheimer's disease and cholesterol, according to Pitts.
Alzheimer’s disease
Alzheimer’s disease is the most common form of dementia in older people. The brains of people with Alzheimer's disease have abnormal clumps of protein called amyloid plaques, tangles of protein fibers called tau, and a loss of connection between brain cells. It is incurable and gets worse with time.
Some studies suggest that cholesterol and Alzheimer's disease may be linked. A 2016 analysis looked at 17 studies published between 1996 and 2014, encompassing more than 23,000 people, and found that high total cholesterol in middle-age was associated with increased risk of Alzheimer’s disease later in life.
Cholesterol and Alzheimer’s disease share a genetic link through a gene called APOE. This gene helps control the building blocks of proteins that carry cholesterol through the blood. A modified version of this APOE gene is known to increase the risk of Alzheimer’s disease, 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 and dementia are connected, says Pitts. “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 heart disease
It’s not just cholesterol that’s linked to dementia. Risk factors for heart disease like high blood pressure, atherosclerosis, smoking and diabetes (high blood sugar levels) 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 damaged blood vessels that decrease blood flow to the brain and cause 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 [high blood pressure], 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 for dementia
Some genetic tests can identify you if you’re likely to develop dementia. “If you are a patient who’s at risk, testing depends on patient preference,” Pitts says.
There are benefits and risks of genetic testing for dementia. 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.”
