Friday, November 20, 2009

Vascular Risk Factors for Alzheimer's Disease

Vascular dementia is the second most common type of dementia, and may account for 15 - 20% all cases of dementia. Vascular dementia can be associated with vascular or circulatory problems in the brain and can often coexist with Alzheimer's disease. Much research is focusing on vascular dementia as well as the role of vascular factors in conjunction with Alzheimer’s disease pathology. Recent findings concerning the overlap between risk factors for vascular disease and Alzheimer's disease, such as high blood pressure, diabetes and high cholesterol levels, have indicated that there may be a strong connection between the development of Alzheimer’s disease and vascular conditions. These findings may have important implications for preventative strategies, suggesting that reducing vascular risk factors could be beneficial for Alzheimer’s disease as well.

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Research reported in the American Academy of Neurology has found that the more vascular risk factors someone has the greater the risk of developing Alzheimer's disease. 'Vascular' means vessels that carry or circulate fluids, such as blood.

As the heart beats, it pumps blood through a system of blood vessels, called the circulatory system. The vessels are elastic tubes that carry blood to every part of the body

• Arteries carry blood away from the heart.
• Veins return blood back to the heart.

Vascular Disease includes any condition that affects the circulatory system, such as peripheral artery disease. This ranges from diseases of your arteries, veins and lymph vessels to blood disorders that affect circulation.
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Vascular risk factors were defined as high blood pressure, diabetes, hypertension, heart disease, and current smoking.

The researchers from Columbia University followed up 1,138 people (average age mid 70's) over 5 years. None of them had dementia when the study began. Their findings showed that
1. The risk of Alzheimer disease increased with the number of vascular risk factors.
2. Diabetes and current smokers were the strongest risk factors by themselves.
3. Four risk factors i.e. diabetes, hypertension, heart disease, and current smoking, were associated with a higher risk of Alzheimer's Disease.
4. People with 3 or more vascular risk factors had nearly three-and-one-half times the risk of developing Alzheimer’s as those with none.

In 2007, Michelle M. Mielke, Ph.D., of Johns Hopkins University School of Medicine in Baltimore, and colleagues conducted a study of 135 people with Alzheimer's disease, who were followed up for a mean three years with a mean 2.1 in-home visits. Vascular factors were determined at baseline, and the Clinical Dementia Rating Scale and Mini-Mental State Examination were administered at follow-up.

More rapid decline on both scales was observed in those with atrial fibrillation, systolic hypertension and angina. The greater the age, the stronger the impact of systolic hypertension, angina and myocardial infarction.

"This suggests that these factors may be age-specific and that there is continued need to treat these conditions as early as possible," the authors write. "As vascular variables are potentially modifiable, these findings suggest means for secondary prevention in Alzheimer disease."

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