A hallmark sign of Alzheimer's disease (AD), is the buildup of the Amyloid plaque on nerves in the brain, which were produced by Amyloid proteins. This same Amyloid protein found in the brain is also produced and found in other organs in the body as well as circulating in the blood stream. While we know from previous studies that higher cholesterol levels increase risk of AD, a groundbreaking new study published this week revealed there is a link between the Amyloid protein produced in the liver, high cholesterol levels and the onset or progression of AD. (1)
Yes, There is a Link Between High Cholesterol Levels and Alzheimer's disease.
This week, a new study published in JAMA revealed that the risk of higher cholesterol levels and greater risk of AD may be due to genetic factors tied to cholesterol produced in the liver. While we know maintaining normal levels of cholesterol is essential for the prevention of cardiovascular diseases, including heart attack and stroke, this new study might lead the way to revise targets for LDL, bad cholesterol levels, to also help reduce AD risk.
Previous study findings showed an increased risk of high Cholesterol and Alzheimer's Disesase with:
- An elevated cholesterol level in your early to mid-40s
- A specific mutation in a gene called APOE, which is responsible for making a protein called apolipoprotein E. This protein combines with fats (lipids) in the body to form molecules called lipoproteins. Lipoproteins act like a "suitcase" and are responsible for carrying cholesterol and other fats through the bloodstream.
In the current study, researchers looked at mice which were bred to only produce Amyloid protein in the liver. The findings showed that the protein was carried in the blood by the lipoproteins from the liver, and passed from the blood stream into the brain. They found that these mice developed nerve damage and brain tissue loss, which was accompanied by nerve and vascular inflammation and brain dysfunction, both commonly observed with AD. Affected mice performed poorly on a learning test that depends on area of the brain that is essential for the formation of new memories.
To date, most models of how AD starts and progresses have focused on brain overproduction of Amyloid protein. But for the vast majority of AD cases, overproduction of the Amyloid protein in the brain is not thought to be the main factor of how AD begins. Instead, lifestyle factors may play a more important role, including a high-fat diet, which might accelerate liver production of cholesterol (lipoproteins) which carry the Amyloid protein to the brain.
While further studies are needed, this finding shows the abundance of these toxic protein deposits in the blood could potentially be addressed through a person's diet and some cholesterol lowering drugs could specifically target lipoprotein Amyloid, therefore reducing their risk or slowing the progression of AD.
What is Cholesterol?
Cholesterol is a waxy, fat-like substance found in the walls of cells in all parts of the body, from the nervous system to the liver to the heart. The body uses cholesterol to make hormones, bile acids, vitamin D, and other substances.
The body makes all the cholesterol it needs. Cholesterol circulates in the bloodstream but cannot travel by itself. As with oil and water, like making a salad dressing, cholesterol (which is fatty) and blood (which is watery) do not mix. So cholesterol travels in packages called lipoproteins, which have fat inside and protein outside.
Two main kinds of lipoproteins carry cholesterol in the blood:
Low density lipoprotein, or LDL, which is called the “bad” cholesterol because it carries cholesterol to tissues, including the arteries. Most of the cholesterol in the blood is the LDL form. The higher the level of LDL cholesterol in the blood, the greater your risk for heart disease.
High density lipoprotein, or HDL, which is called the “good” cholesterol because it takes cholesterol away from tissues to the liver to remove it from your body. A low level of HDL cholesterol increases your risk for heart disease.
Get Your Cholesterol Levels Tested
If you haven’t had a recent cholesterol screening, be sure to get one on your calendar. Experts recommend getting a cholesterol panel every five years. If you have high risk factors for heart disease, your doctor may recommend a yearly test.
It is best to have a test called a “lipoprotein profile.” This blood test is done after fasting for nine to 12 hours and provides a snapshot of your total cholesterol, LDL (bad) cholesterol, HDL (good) cholesterol and triglycerides (a type of fat in your blood).
Your Cholesterol Level goal should be:
- Total cholesterol (a measure of HDL, LDL and other lipoproteins)
- Less than 200 mg/dL
- Less than 150 mg/dL
- LDL (Low-density lipoprotein)
- Less than 130 mg/dL
- Less than 100 mg/dL for those with heart or blood vessel disease and for those with diabetes or high total cholesterol
- HDL (High-density lipoprotein)
- Greater than 55 mg/dL (females)
- Greater than 45 mg/dL (males)
What Can You Do to Lower Your Cholesterol?
A heart-healthy diet from the National Cholesterol Education Program called the TLC (therapeutic lifestyle changes) diet can help lower your cholesterol. This is a low-saturated-fat, low-cholesterol eating plan that calls for less than 7 percent of calories from saturated fat and less than 200 mg of dietary cholesterol per day.
- Reduce saturated fats. Saturated fats, found primarily in red meat and full-fat dairy products, raise your total cholesterol. Decreasing your consumption of saturated fats can reduce your low-density lipoprotein (LDL) cholesterol — the "bad" cholesterol.
- Eliminate trans fats. According to the Food and Drug Administration, most of the trans fat in the foods we eat is formed through a process that adds hydrogen to vegetable oil and converts the liquid into a solid fat at room temperature. This process is called hydrogenation. Trans fat also occurs naturally in food products from animals (e.g., milk, butter, cheese, meat products, etc.). They are often used in margarines and store-bought cookies, crackers and cakes. Trans fats raise overall cholesterol levels. The FDA banned the use of partially hydrogenated vegetable oils on January 1, 2021,
- Eat foods rich in omega-3 fatty acids. Omega-3 fatty acids don't affect LDL cholesterol. But they have other heart-healthy benefits, including reducing blood pressure. Foods with omega-3 fatty acids include salmon, mackerel, herring, walnuts and flaxseeds.
- Increase soluble fiber. Soluble fiber acts like a sponge in your digestive system and can reduce the absorption of cholesterol into your bloodstream. Soluble fiber is found in such foods as oatmeal, kidney beans, Brussels sprouts, apples and pears.
Moderate Alcohol Consumption
If lifestyle changes aren't enough …
Sometimes making lifestyle changes are not enough to lower cholesterol levels. If your doctor recommends medication to help lower your cholesterol, take it as prescribed while continuing your lifestyle changes.
Cholesterol Lowering Medications
Check out this article by the American Heart Association which provides detailed information on cholesterol lowering medications.
View the video on how Cholesterol Lowering Medications work:
Alzheimer's disease Resources
Hudson Valley, NY Alzheimer's Information
Connecticut Alzheimer's Information
Loal FAll Walks to End Alzheimer's
- Virginie Lam, Ryusuke Takechi, Mark J. Hackett, Roslyn Francis, Michael Bynevelt, Liesl M. Celliers, Michael Nesbit, Somayra Mamsa, Frank Arfuso, Sukanya Das, Frank Koentgen, Maree Hagan, Lincoln Codd, Kirsty Richardson, Brenton O’Mara, Rainer K. Scharli, Laurence Morandeau, Jonathan Gauntlett, Christopher Leatherday, Jan Boucek, John C. L. Mamo. Synthesis of human amyloid restricted to liver results in an Alzheimer disease–like neurodegenerative phenotype. PLOS Biology, 2021; 19 (9): e3001358 DOI: 10.1371/journal.pbio.3001358