Antihypertensive Treatment May Help Maintain Memory

Caroline Cassels
September 27, 2007 — New research indicates antihypertensive treatment leads to increased, joint activation of brain areas responsible for memory performance — a finding that suggests such treatment may help patients maintain cognition and memory.
A study led by J. Richard Jennings, PhD, from the University of Pittsburgh, in Pennsylvania, and presented at the American Heart Association (AHA) 61st Annual Fall Conference of the Council for High Blood Pressure Research, showed patients had a 2-fold increase in the joint activation of these areas of the brain after a year of treatment with either the angiotensin-converting enzyme lisinopril or beta blocker atenolol.
While there is an established link between hypertension and mild cognitive deficits, the mechanism has not been clear. Previous research by Dr. Jennings's team used brain imaging to examine the correlation among the activation of the prefrontal areas, parietal areas, and amygdala/hippocampus in hypertensives compared with controls and found it was higher in individuals with high blood pressure.
Increased Correlation
"In the first study, we found that in hypertensive individuals the correlation between levels of activation of these areas of the brain was 0.61. Our next question was, If we successfully treated these individuals [for hypertension], would this finding be reversed and would their brain function look more like normotensives?" Dr. Jennings told Medscape Neurology & Neurosurgery.
"To our surprise, we found that rather than decreasing, the correlation increased to 0.90. Thus, these areas of the brain were nearly always activated at the same level, suggesting there was less specificity, which means that instead of each area doing its own specific job, they were all working at the same time to try to solve the [memory] task," he added.
The study included 28 never-medicated hypertensives, randomized to receive treatment with lisinopril or atenolol for 1 year. All patients underwent psychological and physiological tests, magnetic resonance structural imaging, and positron emission tomography.
Pretreatment correlation of parietal and prefrontal change was 0.61 vs 0.94 after treatment. According to the investigators, similar differences were observed for all areas, with an average pretreatment correlation of 0.66 vs an average posttreatment correlation of 0.91.
Mental Fatigue?
These findings, said Dr. Jennings, suggest hypertensive patients' brains adapt to maintain their intellectual function and that antihypertensive treatment appears to maintain or even augment this adjustment.
At this point, said Dr. Jennings, it is not clear whether there is a "cost" associated with the brain's adaptation to hypertension. "It could mean that [in patients with hypertension] the brain has to work harder, and this could result in mental fatigue, but at this point we just don't know," he said.
This question, he added, will be the focus of future research. In addition, he said, the investigators also want to look at different types of antihypertensive treatments to determine whether they have effects similar to the 2 agents studied in the current work.
According to AHA president Daniel Jones, MD, this study provides reassurance to individuals concerned about potential adverse cognitive effects of antihypertensive treatment. "Treating hypertension is beneficial not only for extending life, but also for improving quality of life," he said in a statement.
The study was funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health.
American Heart Association 61st Annual Fall Conference of the Council for High Blood Pressure Research: Abstract P105. Presented September 27, 2007.