MONDAY, June 30 (HealthDay News) -- A new study suggests an
association between low levels of "good" HDL cholesterol and loss
of memory.
The study, which has followed thousands of British civil
servants for decades, found a 27 percent increased loss of memory
on a word test for those at age 55 with the lowest HDL levels,
compared to those with the highest levels. By age 60, the rate of
memory loss had increased to 53 percent, the study found.
"Our results show HDL cholesterol to be important for memory,"
study author Archana Singh-Manoux said in a prepared statement.
"Thus, physicians and patients should be encouraged to monitor
levels of HDL cholesterol."
The findings of the study, funded in part by the U.S.
government, are published in the July 1 issue of
Arteriosclerosis, Thrombosis and Vascular Biology.
The researchers measured HDL cholesterol levels and gave
short-term verbal memory tests to 3,673 participants, one quarter
of them women, between 1995 and 1997 and again between 2002 and
2004. Participants whose HDL levels decreased during the five years
between tests had a 61 percent increased risk of declining ability
to remember words, the study found.
No link was found between total cholesterol and other blood fat
levels and memory loss. Using statins to lower blood levels of
"bad" LDL cholesterol had no effect on memory loss.
In an accompanying editorial, Anatol Kontush, research director
at the French National Institute for Health and Medical Research
(INSERM), the French equivalent of the U.S. National Institutes of
Health, said the study results should be approached with
caution.
"At this point I would be very cautious. The biochemistry
underlying HDL and brain function is completely unclear," said
Kontush.
Conversely, the relationship between HDL and LDL cholesterol
levels and cardiovascular disease is clear, he said: LDL deposits
can accumulate until they block an artery, while HDL helps keep
arteries clear of those deposits.
"In the brain, we are far from that understanding," Kontush
said. "We need much more basic information before going in to
modify levels."
The most important first step is "just to confirm this
observation," Kontush said. Data from such population studies "can
lead in completely wrong directions," he said.
The statement by Singh-Manoux, who is a senior research fellow
with INSERM and University College London, discussed a possible
cause of the relationship seen in the study. HDL cholesterol could
affect formation of the amyloid plaque that clogs brains of
Alzheimer's patients, she said.
Dr. Ronald Petersen, director of the Alzheimer's Disease
Research Center at the Mayo Clinic and vice chair of the
Alzheimer's Association's medical and scientific advisory council,
was as cautious as Kontush.
"In a general sense, other data are converging to indicate that
managing vascular risk factors may be helpful in Alzheimer's
disease," Petersen said. "This is supportive of that. But at the
same time, we have to be very cautious about whether there is a
direct link between HDL and mental function."
More information
You can learn more about good and bad cholesterol from the
American Heart Association.
