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A blood pressure medication increases blood flow to the brain's memory and learning center, say Alzheimer's disease researchers, but it's unclear whether that could help patients cognitively.

Previous research has shown blood flow to the brain declines in early Alzheimer's disease and that treatment for high blood pressure could reduce the risk of developing dementia, of which Alzheimer's disease is the most common form. The causes of Alzheimer's disease are largely unknown.

The new study, , focused on the blood pressure drug nilvadipine, a calcium channel blocker. Researchers randomly assigned 44 participants to receive either nilvadipine or a placebo for six months. Blood flow to specific regions of the brain was measured using a unique magnetic resonance imaging technique.

Results showed blood flow to the hippocampus – the brain's memory and learning center – increased by 20% among the nilvadipine group. Blood flow to other regions of the brain was unchanged.

The treatment holds promise because it doesn't appear to decrease blood flow to the brain, which could do more harm than good, study lead author Dr. Jurgen Claassen said in a news release. "Even though no medical treatment is without risk, getting treatment for high blood pressure could be important to maintain brain health in patients with Alzheimer's disease," said Claassen, associate professor at Radboud University Medical Center in Nijmegen, Netherlands.

Given the small number of participants and short follow-up time, researchers were unable to study the effects of the cerebral blood flow increase on cognition and brain structure.

Study participants were screened between 2013 and 2015 as part of a larger research project comparing nilvadipine to a placebo among more than 500 people with mild to moderate Alzheimer's disease. Their average age was 73; more than half were women, and most were white.

The effects on cerebral blood flow were not measured in that larger study, but overall, researchers saw no clinical benefit from nilvadipine. However, a subgroup of participants with only mild Alzheimer's disease symptoms did have a slower decline in memory.

"In the future, we need to find out whether the improvement in blood flow, especially in the hippocampus, can be used as a supportive treatment to slow down progression of Alzheimer's disease, especially in earlier stages of disease," Claassen said.

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