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Cholesterol Levels Linked to Brain Changes of Alzheimer’s Disease

Study: High Cholesterol Predicts Brain-Clogging Protein Deposits on Autopsy
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WebMD Health News

Sept. 12, 2011 -- High cholesterol levels are associated with changes in the brain that are characteristic of Alzheimer’s disease, a new study shows.

For the study, which is published in the journal Neurology, researchers used blood tests to measure cholesterol in 147 Japanese adults 10 to 15 years before their deaths. Fifty of them (or 34%) had been diagnosed with dementia.

Tissue samples from their brains were then examined on autopsy.

Those who had total cholesterol levels over 224 mg/dL in mid- to late life, before they had any symptoms of Alzheimer’s, were at least seven times more likely to have beta-amyloid plaques in their brains by the time they died, compared to people whose cholesterol was under 173 mg/dL. The American Heart Association considers total cholesterol levels below 200 mg/dL to be desirable.

LDL, or “bad,” cholesterol over 155 mg/dL was also strongly associated with the likelihood of developing beta-amyloid plaques, compared to people whose LDL was lower than 106 mg/dL. People with high LDL levels were at least eight times more likely to display pathologic features of Alzheimer’s disease. Ideal LDL levels are felt to fall below 100 mg/dL, according to the AHA.

The relationship to cholesterol values remained after researchers adjusted for other things that are thought to influence the risk of Alzheimer’s disease, like age, sex, body weight, aerobic exercise, blood pressure, a history of stroke, and blood sugar and insulin levels.

Cholesterol and the Brain

Beta-amyloid is a sticky protein that clogs the brains of people who have Alzheimer’s disease.

Though researchers aren’t sure how beta-amyloid is related to the memory loss and other changes that occur with Alzheimer’s, one theory is that plaques that form between nerve cells may jam the brain’s communication network.

“Our study suggests that serum cholesterol in excess of a certain threshold level would trigger the plaque formation,” says study researcher Kensuke Sasaki, MD, an assistant professor of neuropathology at Kyushu University in Fukuoka, Japan, says in an email to WebMD.

People who keep their cholesterol down as they age might therefore be able to reduce the risk of plaque formation, Sasaki says.

In Alzheimer’s, plaques are usually found in conjunction with another problem called tangles. Tangles are twisted fibers of tau protein that build up inside nerve cells.

It had been thought that a buildup of beta-amyloid might cause tangles and that growing numbers of tangles in the brain might lead to Alzheimer’s symptoms.

Curiously, though, the study found that while cholesterol seemed to be associated with the development of plaques, it did not seem to influence tangles.

“This study lends credence to the notion that there may be different factors driving amyloid pathology versus tangle pathology,” says Marc L. Gordon, MD, chief of Neurology at Zucker Hillside Hospital in Glen Oaks, N.Y. and an Alzheimer’s researcher at The Feinstein Institute for Medical Research in Manhasset, N.Y.

He says the study may mean that sequence of brain damage in Alzheimer’s is less straightforward than “amyloid causes tangles causes disease,” Gordon says.

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Your total cholesterol level is Borderline High, but fortunately your level of "bad" LDL cholesterol is near optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have other non-measured increases in LDL-like particles that can increase heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

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Your total cholesterol level is Borderline High. Your level of "bad" LDL cholesterol is High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol level is Borderline High. But your level of "bad" LDL cholesterol is Very High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol is High, but your level of "bad" LDL cholesterol is optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have elevated secondary lipids, such as non-HDL particles that increase the risk of heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol is High, but your level of "bad" LDL cholesterol is near optimal. This could mean you have a high level of high-density lipoprotein, or "good" HDL cholesterol, which protects against heart disease. Or you could have elevated secondary lipids, such as non-HDL particles that increase the risk of heart disease. Your LDL level also could be optimal if you are taking a statin medication. Please check with your doctor to get your complete lipid profile and see if you may need additional treatment. In the meantime, find more information on WebMD's Cholesterol Health Center.

Your total cholesterol level is High. Your level of "bad" LDL cholesterol is Borderline High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels!

Your total cholesterol level is High. Your level of "bad" LDL cholesterol is High, too. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels! If you are struggling to bring down your total cholesterol and LDL cholesterol levels, your doctor may prescribe medication, such as statins. Following medication, dietary, and exercise instructions should result in improvements.

Your total cholesterol level is High, and your level of "bad" LDL cholesterol is Very High. Working to bring down your total cholesterol decreases your LDL cholesterol level. You can do this by exercising more and eating less food with saturated fats. Check food labels! If you are struggling to bring down your total cholesterol and LDL cholesterol levels, your doctor may prescribe statins or other cholesterol-lowering medications.

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