Hypertension drug holds promise for Alzheimer's disease

Seeking new treatments to slow the progression of Alzheimer’s disease, European researchers have found the blood pressure drug nilvadipine increased blood flow to the brain’s memory and learning centre among people with Alzheimer’s disease without affecting other parts of the brain.

Published in the journal Hypertension, the findings indicate that the known decrease in cerebral blood flow in patients with Alzheimer’s can be reversed in some regions. However, an important question is whether this observed increase in cerebral blood flow translates to clinical benefits.

Alzheimer’s disease is the most common form of dementia — but though risk of the disease increases with age, the causes remain largely unknown. Previous research has however shown that blood flow to the brain declines in early Alzheimer’s disease, and other studies have hinted that high blood pressure treatment could reduce the risk of developing dementia.

With this in mind, researchers led by Radboud University Medical Center sought to discover whether nilvadipine — a calcium channel blocker used to treat high blood pressure — could help treat Alzheimer’s disease by comparing it against a placebo among people with mild-to-moderate Alzheimer’s disease. The researchers randomly assigned 44 participants to receive either nilvadipine or a placebo for six months. Neither researchers nor the participants knew who received the drug or the placebo that was evenly divided among the two groups.

At the study’s start and after six months, researchers measured blood flow to specific regions of the brain using a unique MRI technique. Results showed that blood flow to the hippocampus — the brain’s memory and learning centre — increased by 20% among the nilvadipine group compared with the placebo group, with blood flow to other regions of the brain unchanged in both groups.

“This high blood pressure treatment holds promise as it doesn’t appear to decrease blood flow to the brain, which could cause more harm than benefit,” said lead author Jurgen Claassen, an associate professor at Radboud University Medical Center.

The study participants were screened as part of a larger research project comparing nilvadipine to placebo among more than 500 people with mild-to-moderate Alzheimer’s disease. In that larger project, effects on cerebral blood flow were not measured and no overall clinical benefit was noted with use of nilvadipine. However, a subgroup of patients with only mild symptoms of disease did show benefit, in the sense of a slower decline in memory.

The study is one of a few to use this MRI technique to probe the effects of treatment on cerebral blood flow, making additional research critical — particularly given that the small number of participants of similar race and ethnicity means that the results may not apply to other populations. It has also been noted that sample sizes were too small and follow-up time too short to reliably study the effects of this cerebral blood flow increase on structural brain measures and cognitive measures.

“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.

Image credit: ©stock.adobe.com/au/Bulat

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