Elevated cholesterol levels
linked to known signs of Alzheimer's disease
People with high cholesterol may have a higher
risk of developing Alzheimer's disease, according to a study published
in the September 13, 2011, issue of NeurologyR, the medical journal
of the American Academy of Neurology.
"We found that high cholesterol levels were significantly
related to brain plaques associated with Alzheimer's disease,"
said study author Kensuke Sasaki, MD, PhD, of Kyushu University
in Fukuoka, Japan.
For the study, the cholesterol levels were tested for 2,587 people
age 40 to 79 who had no signs of Alzheimer's disease. Then they
examined 147 autopsied people who died after a long observation
period (10 to 15 years). Of those, 50 people, or 34 percent, had
been diagnosed with dementia before death.
The autopsies looked for plaques and tangles in the brain, both
known to be trademark signs of Alzheimer's disease. Plaques are
an accumulation of a form of the protein amyloid, which occurs between
nerve cells. Tangles are an accumulation of a different protein,
called tau, which occurs inside nerve cells.
People with high cholesterol levels, defined by a reading of more
than 5.8 mmol/L, had significantly more brain plaques when compared
to those with normal or lower cholesterol levels. A total of 86
percent of people with high cholesterol had brain plaques, compared
with only 62 percent of people with low cholesterol levels.
The study found no link between high cholesterol and the tangles
that develop in the brain with Alzheimer's disease.
In addition to high cholesterol increasing the risk of Alzheimer's
disease, Sasaki previously found that insulin resistance, a sign
of diabetes, may be another risk factor for brain plaques associated
with Alzheimer's disease.
"Our study clearly makes the point that high cholesterol may
contribute directly or indirectly to plaques in the brain,"
Sasaki said, "but failed treatment trials of cholesterol-lowering
drugs in Alzheimer's disease means there is no simple link between
lowering cholesterol and preventing Alzheimer's."
This study was supported by the Japan Society for the Promotion
of Science and the Japanese Ministry of Health, Labor and Welfare.
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