"While hypertension is not a cause of Alzheimer's disease, our study shows that it is another hit on the brain that increases its vulnerability to the effects of the disease," said Raji.
Hypertension is a condition caused when the blood circulates through the arteries with too much force. People with hypertension are at elevated risk for heart attack, stroke and aneurysm. Recently, there has been mounting evidence tying cardiovascular health to brain health. "This study demonstrates that good vascular health is also good for the brain," said co-author Oscar Lopez, M.D., professor of neurology and psychiatry at the University of Pittsburgh.
"Even in people with Alzheimer's disease, it is important to detect and aggressively treat hypertension and also to focus on disease prevention," he added.
The researchers used arterial spin-labeled magnetic resonance imaging (MRI), for the study, which can measure blood flow in the brain, to image 68 older adults. Arterial spin-labeled MRI is a novel, noninvasive technique that requires no external contrast agent.
The patient group included 48 normal individuals, including 38 with hypertension and 10 without; 20 Alzheimer's patients, including 10 with hypertension and 10 without; and 20 adults with mild cognitive impairment, 10 with hypertension and 10 without.
Mild cognitive impairment, which affects brain functions such as language, attention and reasoning, is a transition stage between normal aging deficits in the brain and greater levels of dementia.
The MRI results showed that in all the patient groups, blood flow in the brain was substantially decreased in patients with hypertension compared to those without. Cerebral blood flow was lowest among the Alzheimer's patients with hypertension, but the normal group with hypertension showed significantly lower cerebral blood flow than the normal group without hypertension.
"These results suggest that by changing blood flow to the brain, hypertension—treated or untreated—may contribute to the pathology of Alzheimer's," Raji said.
The study was presented Nov 29 at the annual meeting of the Radiological Society of North America (RSNA).