Drop in systolic blood pressure may indicate imminent likelihood of Alzheimer’s disease or dementia

Jul 2 2004

Journal of the American Heart Association reports that a significant drop in systolic blood pressure may indicate imminent likelihood of Alzheimer’s disease or dementia in some elderly people.

A research team from Karolinska Institutet in Stockholm led by professor Laura Fratiglioni, M.D., Ph. D., found that a substantial drop in systolic blood pressure (the higher number in a blood pressure reading) predicted the onset of dementia in people with a systolic pressure of less than 160 millimeters of mercury (mm Hg). A drop in systolic pressure of 15 mm Hg or more was linked to a three-fold increase in the risk of getting Alzheimer’s disease or other dementia.

The same 15 mm Hg or more decrease in patients who already had vascular disorders such as stroke and diabetes mellitus increased their risk of Alzheimer’s 2.4 times, and 2.5 times for all types of dementia.

“Our findings imply that poor blood flow in the brain, resulting from an extensive decline in blood pressure, may promote the dementia process,” said lead author Chengxuan Qiu, M.D., a postdoctoral epidemiologist at the Karolinska Institutet.

However, because so few studies have addressed the connection between blood pressure decline and dementia, these findings need further verification. “Indeed, we have to consider that patients with dementia experience a decline in blood pressure some years before diagnosis, which continues to decline after the onset of dementia,” Fratiglioni said.

Alzheimer’s disease is the most common cause of dementia in Western countries. Other causes include repeated strokes and secondary dementia resulting from neurological disorders such as Parkinson’s disease.

This study aimed to verify blood pressure variations before and after dementia diagnosis, and to investigate whether blood pressure decline was predictive of Alzheimer’s disease and dementia.

Researchers examined 947 people age 75 or older who had no evidence of dementia when they entered a large study of aging and dementia conducted in the Kungsholmen district of Stockholm. Each participant had blood pressure measurements taken and physical examination done when they began the study and again three and six years later.

Of these enrollees, 147 were diagnosed with Alzheimer’s disease and 39 with other dementia at the three-year follow-up examination. At six years, researchers diagnosed another 91with Alzheimer’s and an additional 27 with other types of dementia.

American Heart Association spokesperson Daniel Jones, M.D.,cautioned that the study doesn’t mean high blood pressure in the elderly should be untreated.

“The results of this study are of interest to the research community as we attempt to understand the complex relationship between blood pressure and dementia,” Jones said. “However, data from well-conducted randomized clinical trials have consistently supported the view that treating systolic blood pressure to 140 mm Hg or less in the elderly is beneficial. No clinical trial data to date has indicated any adverse impact on cognitive function. Indeed, there is strong data from some studies that support the idea that lowering blood pressure prevents dementia.”