Role of cholesterol in Alzheimerís disease unclear
(25 February 2007: VIDYYA MEDICAL NEWS SERVICE) -- It sounds simple: The lower your cholesterol, the better your heart health. But a manís heart and his head donít always agree. In fact, the relationships among cholesterol levels, psychological function, and neurologic disorders are complex and sometimes controversial, reports the March 2007 issue of Harvard Menís Health Watch.
There are two major forms of dementia: vascular dementia and Alzheimerís disease. Vascular dementia results when blood vessel damage deprives the brain of oxygen. Brain cells die as a result, and mental function suffers. Some studies link high cholesterol levels to an increased risk of cognitive impairment, but others report the opposite. More research is needed to sort this out, but even now, investigations of HDL (good) cholesterol and mental function have consistently reported that high HDL levels appear to help preserve mental function in older people.
The connection between Alzheimerís disease and cholesterol is even more complex. Scientists have learned much of the damage of Alzheimerís comes from deposits of a sticky protein, called beta-amyloid, in vital areas of the brain. In some studies, high cholesterol levels appear to accelerate the formation of beta-amyloid plaques. People with the genetic trait that increases the level of a particular cholesterol transport protein have a greatly increased risk of late-onset Alzheimerís.
The urgent question is whether cholesterol-lowering drugs, such as statins, can reduce the risk of Alzheimerís disease. In the most recent studies, people who took statins did not appear to be at lower risk for the disease. Additional research is under way. Right now, it is too early for firm conclusions on the relationships among cholesterol, cognitive function, and statin therapy.
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