In a large-scale meta-analysis published June 2021 in the journal Hypertension, researchers found that people who took hypertension medications that travel out of blood vessels and enter the brain, known as crossing the blood-brain barrier, experienced less cognitive decline than those who used blood pressure drugs that stay only in the bloodstream. “We know that lowering blood pressure is beneficial for cognitive decline and risk for dementia, but there’s lots of different drugs. And the question was, do these drugs work through a variety of different mechanisms to benefit cognitive decline or is it just about lowering blood pressure?” says the study’s corresponding author Daniel Nation, PhD, an associate professor of psychological science and a faculty member of the Institute for Memory Impairments and Neurological Disorders at the University of California in Irvine (UCI MIND). Dr. Nation and his colleagues compared the research on drugs with and without blood-brain barrier crossing ability that affect the renin-angiotensin system, a hormone system that’s related to blood pressure and plays a role in learning and memory. They analyzed data on two classes of drugs: angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), which are commonly used in the treatment of hypertension. In all, the analysis included nearly 13,000 people older than 50 in 14 different studies conducted in six countries. “This wasn’t an examination of one specific drug or even one class of drugs; it was a property of the drug — whether it gets into the brain. If physicians were convinced that this property is valuable, it wouldn’t require a dramatic change to their prescribing practice. They could simply choose another drug within the same family that crosses the blood-brain barrier,” Nation said in a press release.
A Fluke in the Results and Areas for Future Research
One result that left researchers scratching their heads was the fact that the patients who took drugs that do not cross the blood-brain barrier had better outcomes on attention compared with those who took drugs that cross to the brain. Although cardiovascular disease does negatively affect attention, it is not a sign of dementia. Nation and Jean Ho, PhD, a postdoctoral scholar at the UCI MIND, are pursuing new studies for a better understanding of those results. For now though, this new research could help pave the way for different prescribing practices that take into account other diseases linked to hypertension. “Alzheimers has been built as a disease of the brain in which nothing else has anything to do with it,” says Constantino Iadecola, PhD, the director of the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine, who was not involved in the study. “Vascular damage to the brain is caused mainly by high blood pressure. It’s also a major contributor to Alzheimer’s disease. So the message to the community is that if you treat high blood pressure, you also treat Alzheimer’s disease.” Iadecola advises patients to check your blood pressure regularly to get treated as soon as possible. He also advises Black patients in particular who have a tendency toward hypertension to treat high blood pressure now in any shape or form.
