Alzheimer's, cardiovascular disease share risk factors
Cholesterol levels, diabetes, & hypertension – known risk factors for strokes & heart attacks – can contribute to risk of cognitive decline and dementia later in life.
PHILADELPHIA, 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 be held July 17-22, 2004, at the Pennsylvania Convention Center in Philadelphia, Pennsylvania.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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