Hypertension

27 January 2010

Blood pressure linked to dementia

If the cardiologist's warnings do not scare you, consider this: controlling blood pressure just might be the best protection yet known against dementia.

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If the cardiologist's warnings do not scare you, consider this: controlling blood pressure just might be the best protection yet known against dementia.

In a flurry of new research, scientists scanned people's brains to show hypertension fuels a kind of scarring linked to later development of Alzheimer's disease and other dementias. Those scars can start building up in middle age, decades before memory problems will appear.

The evidence is strong enough that the National Institutes of Health soon will begin enrolling thousands of hypertension sufferers in a major study to see if aggressive treatment - pushing blood pressure lower than currently recommended - better protects not just their hearts but their brains.

Blood pressure preventable

"If you look ... for things that we can prevent that lead to cognitive decline in the elderly, hypertension is at the top of the list," Dr Walter Koroshetz, deputy director of NIH's National Institute of Neurological Disorders and Stroke, told The Associated Press.

Age is the biggest risk factor for Alzheimer's disease and other forms of dementia that affect about one in eight people 65 or older.

Scientists have long noticed that some of the same triggers for heart disease - high blood pressure, obesity, diabetes - seem to increase the risk of dementia, too. But for years, they thought that link was with "vascular dementia," memory problems usually linked to small strokes, and not the scarier classic Alzheimer's
disease.

Now those lines are blurring as specialists realise that many if not most patients have a mix of the two dementias. Somehow, factors like hypertension - blood pressure readings of 140 over 90 or higher - that weaken arteries also seem to spur Alzheimer's disease-like processes.

One suspect: Scarring known as white matter lesions. White matter acts as the brain's telephone network, a system of axons, or nerve fibers, that allow brain cells to communicate with each other. Even slightly elevated blood pressure can damage the tiny blood vessels that nourish white matter, interrupting those signals.

Strong new studies

MRI scans showed women 65 and older with high blood pressure had significantly more white matter lesions in their brains eight years later. The study included 1,403 women who were enrolled in a memory subset of the landmark Women's Health Initiative that tracked postmenopausal health. The worse their blood pressure, the
higher volume of white matter damage, says the study published in the Journal of Clinical Hypertension.

"This is a silent disease in the brain," says lead researcher Dr Lewis Kuller of the University of Pittsburgh. "It's evolving over time and it leads to very bad outcomes."

The journal Stroke just published similar evidence from a Johns Hopkins University-led study that tracked 983 people for more than 15 years, starting in middle age. The longer people spent with uncontrolled high blood pressure, the more white matter damage they accumulated. The researchers could see a change with each 20-point jump in too-high systolic pressure, the top number in a blood-pressure reading.

Hypertension not the only culprit

Clearly, hypertension alone doesn't doom someone to later dementia. Far more people, nearly one in three US adults, have hypertension.

And there are plenty of other reasons to lower blood pressure: Hypertension is a leading cause of heart attacks, strokes and kidney failure. - (Lauran Neergaard/Sapa, January 2010)

 

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Hypertension expert

Dr Jacomien de Villiers qualified as a specialist physician at the University of Pretoria in 1995. She worked at various clinics at the Department of Internal Medicine, Steve Biko Hospital, these include General Internal Medicine, Hypertension, Diabetes and Cardiology. She has run a private practice since 2001, as well as a consultant post at the Endocrine Clinic of Steve Biko Hospital.

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