Hypertensives Ability to Cross Blood-Brain Barrier Tied to Cognitive Changes
NEW YORK (Reuters Health) – Older hypertensive patients taking renin-angiotensin drugs that cross the blood-brain barrier (BBB) show slightly less memory decline over time than do those taking non-penetrant antihypertensives, a new meta-analysis suggests.
Conversely, they had worse attention over time, researchers report in the journal Hypertension.
“We found that among older adults being treated for hypertension, patients taking angiotensin-II-receptor blockers (ARBs) or angiotensin-converting-enzyme inhibitors (ACEIs) that cross the blood-brain barrier showed better memory over three years than patients taking ARBs or ACEIs that do not cross the BBB,” said Dr. Daniel A. Nation of the University of California, Irvine.
“We know treating blood pressure can prevent cognitive decline, but this study addressed how there may be other benefits to brain-penetrant antihypertensive drugs beyond blood pressure lowering,” he told Reuters Health by email. “This is important because both hypertension and memory decline in the elderly are common.”
Dr. Nation and his colleagues analyzed longitudinal data on almost 13,000 individuals who took part in studies from Australia, Canada, Germany, Ireland, Japan and the United States.
The team compared changes over time in various cognitive scores between cognitively normal patients who took renin-angiotensin system (RAS) drugs that cross versus don’t cross the BBB.
After adjusting for age, education and sex, the recall part of verbal memory showed the greatest positive effect size, at 0.07 (P=0.03), suggesting that participants who took BBB-crossing drugs had better memory recall over three years of follow-up.
Attention showed the lowest effect size, at -0.17 (P=0.02), which seems to indicate that older adults who used non-BBB-crossing drugs displayed better attention over time.
“Despite findings supporting our hypothesis regarding BBB-crossing RAS drugs and memory decline, our overall findings were mixed, as we unexpectedly found that older adults taking non-BBB-crossing drugs displayed better attention over follow-up, compared with the BBB-crossing group,” the researchers write.
“Several factors may explain this unexpected finding,” they add. “In contrast to memory recall ability, attentional processes may be impacted by spurious factors unrelated to neuropathological processes, including test engagement, stress, and depression.”
Dr. Jason D. Hinman, an associate professor of neurology at David Geffen School of Medicine at the University of California, Los Angeles, called the findings “exciting,” noting that “the data suggest similarities to the off-target benefits of statins that reach beyond cholesterol lowering.”
“The findings are modest,” Dr. Hinman, who was not involved in the study, told Reuters Health by email. “As it was here, the impact of risk factor modifications on cognitive performance is usually small. Further evaluation in a study directly comparing RAS drugs that penetrate the brain with those that do not is definitely warranted.”
“In elderly patients at risk for memory decline, I will actively consider BBB permeability when prescribing,” he added. “If a particular patient needs to be on anti-hypertensives anyway, why not try to maximize the brain-health benefit? The downside is minimal, as these are all safe, approved, well tolerated drugs that have been used for decades.”
Dr. Hinman noted that a limitation of the study is that the direct pharmacokinetics of brain penetration were inferred from the literature, not assessed.
Dr. Sevil Yasar, an associate professor of medicine at Johns Hopkins School of Medicine in Baltimore, Maryland, also observed that the lack of account for blood pressure control was a weakness. “We do not know whether the beneficial effect is due to blood pressure control or due to other benefit,” she told Reuters Health by email.
“People with hypertension are at increased risk for cognitive impairment, and these results can guide clinicians when choosing antihypertensive medications for their older patients,” advised Dr. Yasar, who also was not involved in the study. “However, clinical trials are needed to confirm these findings.”
The research team is planning further related research.
The study did not receive commercial funding, and none of the authors report conflicts of interest.
SOURCE: https://bit.ly/2Ud8UjC Hypertension, online June 21, 2021.
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