Higher Cholesterol Levels Related to Brain Plaques Associated with Alzheimers
There is a saying that suggests that what is good for the heart is also good for the brain. The reverse is also true – risk factors for heart disease are associated with brain changes that can lead to dementia later in life. A new study from Japanese researchers builds on the growing body of evidence that controlling cholesterol levels can help decrease the risk of developing Alzheimer’s disease.
Kensuke Sasaki MD PhD of Kyushu University and colleagues began the study by testing cholesterol levels for over 2,500 people between the ages of 40 and 79 who had no signs of Alzheimer’s disease. After a long observation period of 10 to 15 years, 147 died and were autopsied. Fifty of the final study patients had been diagnosed with dementia prior to their death.
The researchers were looking for beta-amyloid plaques and tau protein tangles in the brains which are characteristic physical signs of Alzheimer’s disease. Eighty-six percent of who had been identified with high blood cholesterol levels – defined as being greater than 224 mg/dL - had brain plaques, versus only 62% of those with lower cholesterol levels (under 173 mg/dL). Those with higher levels of LDL (“bad”) cholesterol were at least eight times more likely to display the features of Alzheimer’s disease.
The researchers found no such association between cholesterol levels and tau protein tangles.
“Our study suggests that serum cholesterol in excess of a certain threshold level would trigger the plaque formation,” says Dr. Sasaki, an assistant professor of neuropathology. However, the connection between high cholesterol and Alzheimer’s may not be that simple. Studies that use cholesterol-lowering drugs called statins have failed to show benefit in Alzheimer’s patients.
Cholesterol’s role in Alzheimer’s disease progression is likely a part of a bigger physiological process. This past April, researchers in China found the combination of high cholesterol, high blood pressure, and diabetes affected vascular health which increased the risk of progressing from mild cognitive impairment (MCI) to full-blown Alzheimer’s dementia. Sasaki’s research did also find an association between insulin resistance and brain plaque formation.
Because these risk factors could present a preventable cause of some dementia cases, it is recommended that patients take control of blood pressure, blood sugar, and cholesterol levels through healthy lifestyle changes such as an improvement in diet and increasing physical activity. The American Heart Association recommends keeping total cholesterol levels below 200 mg/dL and LDL cholesterol levels below 100 mg/dL. Fasting blood sugar levels should be between 70 and 100 mg/dL.
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2. American Academy of Neurology (2011, April 14). Treating high blood pressure, cholesterol, diabetes may lower risk of Alzheimer's disease. ScienceDaily. Retrieved September 13, 2011, from http://www.sciencedaily.com-/releases/2011/04/110413161250.htm
3. American Academy of Neurology (2008, April 10). Diabetes In Mid-life Linked To Increased Risk Of Alzheimer's Disease. ScienceDaily. Retrieved September 13, 2011, from http://www.sciencedaily.com¬/releases/2008/04/080409170343.htm