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Good Cholesterol May Keep Your Brain Working
Hypertension and diabetes medications might lower
the risk and impact of Alzheimer's
July 20, 2004 – Higher levels of
"good" cholesterol in middle age may help preserve brain function in
later years, according to research reported today at The 9th
International Conference on Alzheimer's Disease and Related Disorders (ICAD),
presented by the Alzheimer's Association.
In addition, preliminary evidence was presented
suggesting that some hypertension and diabetes medications might lower
the risk and impact of Alzheimer's. And, a study showed that
cardiovascular risk factors are associated with cognitive decline. These
studies add to mounting evidence that some of the health factors that
contribute to cardiovascular disease – and resultant strokes and heart
attacks – also increase the risk of Alzheimer's.
"Research data leaves little doubt that we should
focus on helping people to manage their numbers – blood pressure,
cholesterol, blood sugar levels, and body weight – as a way to promote
healthier aging and perhaps reduce risk of Alzheimer's," said Marilyn
Albert, Ph.D., chair of the Alzheimer's Association's Medical &
Scientific Advisory Council.
Raising "Good" Cholesterol May Protect Against
Dementia
Researchers at Harvard University and Brigham and Women's Hospital in
Boston reported on the relationship between cardiovascular risk factors
and cognitive function in 4,081 women aged 65 years and older. The
researchers correlated performance on a battery of neuropsychological
tests with levels of cholesterol and triglycerides determined several
years earlier.
The only factor that influenced cognitive
performance was HDL (or "good") cholesterol. The researchers found a
consistent increase in cognitive health paralleling higher levels of
HDL. A less robust correlation was seen for lower levels of LDL (or
"bad") cholesterol and better cognitive performance. Triglyceride levels
did not appear to influence cognition.
"These results suggest the possibility that simple,
well-established lifestyle modifications to increase HDL levels –
increased physical activity, moderate alcohol intake, and high intake of
mono-unsaturated fatty acids – could have a substantial public health
impact beyond heart disease," said study author Elizabeth Devore, a
doctoral candidate in epidemiology at the Harvard School of Public
Health.
Constellation of Heart Disease and Metabolic
Factors Promote Cognitive Decline Various factors that contribute to
diabetes mellitus and cardiovascular disease also appear to promote a
decline in mental function in the elderly. Jacobo Mintzer, M.D., of the
Medical University of South Carolina in Charleston presented data from
the Charleston Heart Study. In a sample of more than 700 men and women,
Mintzer measured diabetes and cardiovascular disease risk factors and
correlated them with cognitive health several years after the
measurements.
Mintzer and colleagues found that the presence of
high cardiovascular risk factors increased the risk of later cognitive
decline, with a particularly strong effect in African Americans.
Specifically, the presence of coronary heart disease, high cholesterol,
or hypertension also led to more rapid cognitive decline during aging.
Interestingly, they found that although the
diagnosis of diabetes increased the risk of cognitive decline by as much
as two fold, the presence of high levels of fasting glucose (therefore,
low insulin levels) substantially decreased the risk of cognitive
decline in diabetic patients.
"One possible explanation for this apparent
contradiction may lie in recent research suggesting that an enzyme that
breaks down insulin may also have a role in breaking down key abnormal
proteins implicated in Alzheimer's disease," Mintzer said.
"These data help to confirm the idea that
cardiovascular health and brain health are closely related. By working
to prevent strokes and heart attacks, we may also delay cognitive
decline in the elderly," Albert said.
Diabetes Drug Effective in Early Alzheimer's
Disease
Recent research has indicated that diabetes may increase the risk for
Alzheimer's disease. Some scientists believe that impaired insulin
function is the common link between the two diseases.
At ICAD, researchers presented data on a 24-week
pilot trial of the diabetes drug rosiglitazone in patients with mild
cognitive impairment (MCI) or very mild Alzheimer's disease. The 20
subjects who received rosiglitazone – a drug that boosts insulin
activity – did not decline in their performance on memory and attention
tests, whereas the 10 patients who received placebo declined at a rate
typical for Alzheimer's.
"Notably, the amount of memory preservation was
related to the therapeutic effects of rosiglitazone on blood insulin
levels," said authors Suzanne Craft, Ph.D., and G. Stennis Watson,
Ph.D., of the VA Puget Sound Health Care System in Seattle, Washington.
While the mechanism for the therapeutic benefit
remains to be determined, the researchers hypothesized that,
"rosiglitazone may have beneficial effects on brain insulin levels, beta
amyloid levels, and inflammation," all of which have been linked to
Alzheimer's disease.
Some Anti-Hypertension Medicines Associated with
Reduced Risk of Alzheimer's
Some high blood pressure drugs may reduce the risk of Alzheimer's
disease, according to a study presented at ICAD. A number of research
studies have linked high blood pressure with an increased risk of
Alzheimer's disease, and several have suggested that anti-hypertensive
medications may reduce this risk. Researcher Ara S. Khachaturian, Ph.D.,
and colleagues examined data from an ongoing study of memory and aging
among more than 3,300 residents age 65 and over from Cache County, Utah.
Khachaturian and colleagues found that participants
who had used anti-hypertension medications had a lower risk of getting
Alzheimer's. This benefit seemed most closely related to the use of
diuretics. Among this group of drugs, "potassium-sparing" diuretics were
associated with the greatest reduction in Alzheimer risk. The use of
other hypertension drugs, such as ACE (angiotensin converting enzyme)
inhibitors, calcium channel blockers, and beta-blockers, did not affect
Alzheimer risk.
"Although these results require replication, we
suggest further investigation into the possible neuroprotective effects
of diuretics and potassium-sparring diuretics," said Khachaturian.
Maintain Your Brain
The Alzheimer's Association wants Americans to understand that healthy
aging is a process that should begin sooner in life rather than later in
order to remain healthy of body and mind for as long as possible.
More research is necessary, especially in the form
of prevention trials, but there is increasing evidence that healthy
lifestyle habits Americans are familiar with today such as managing your
numbers – your blood pressure, cholesterol, and blood sugar levels, as
well as your body weight – contribute to healthier aging and may also
decrease your risk for Alzheimer's.
The Association calls on all Americans to join its
Maintain Your Brain campaign: learn about Alzheimer's disease, adopt
healthy lifestyles by managing their numbers and engaging in exercise
and social activities, and join the Association in advocating for more
funds for research.
The 9th International Conference on Alzheimer's
Disease and Related Disorders (ICAD), presented by the Alzheimer's
Association, is the largest gathering of Alzheimer researchers in
history. More than 4,500 scientists from around the world will present
and discuss the findings of 2,000 studies showcasing the newest
treatment advances in Alzheimer's disease and steps toward prevention.
ICAD will continue through July 22, 2004, at the Pennsylvania Convention
Center in Philadelphia, Pennsylvania.
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