Welcome to InCirculation.net
InCirculation.net is a professional cardiovascular resource intended for a global audience of specialists, generalists, researchers, and other healthcare professionals
Cardiovascular news provides daily news updates to help you stay informed.
Treated hypertension patients require increased coordination of brain blood flow for memory tasks
28 September 2007
MedWire News: Blood flow to brain regions that support memory function in patients with hypertension differs from that in people with normal blood pressure (BP) levels, a difference that is compounded by their antihypertensive treatment, report US researchers.
"It does not mean that those with high BP were remembering significantly less," said lead investigator Richard Jennings, from the University of Pittsburgh School of Medicine in Pennsylvania, USA. "Rather, the brain areas acting together during memory required more blood flow to remember the same things as people [without high BP]."
Jennings explained that four areas of the brain become active during memory tasks: the thalamus; posterior parietal; prefrontal area; and hippocampus.
He and colleagues examined the effect of hypertension and its treatment on task-related changes in the cerebral blood flow (CBF) in these regions. The researchers randomly assigned 28 never-medicated hypertensive individuals to treatment with an ACE inhibitor or beta blocker.
Participants performed a panel of psychological and physiological tests before and after 1 year of treatment, during which their regional CBF (rCBF) was monitored using magnetic resonance imaging and positron emission tomography.
The researchers found that the correlation of increased rCBF among different regions during specific tasks that assess increasing spatial memory working load was higher for people with high BP than those with normal BP.
"That means that more brain tissue was getting coordinated during the memory task in people with high BP than in those with normal BP," explained Jennings.
He said they expected the correlation in the hypertensive group to decrease after treatment, so that these participants "would look more like those with normal BP."
Instead, the correlation increased. For example, the correlation of parietal and prefrontal rCBF change was 0.61 before treatment compared with 0.94 post-treatment (p=0.006). Similar differences were seen for all areas, with an average pre-treatment correlation of 0.66 and post-treatment correlation of 0.91.
"Further research is needed to find out what this means to memory function, and whether having hypertension and taking antihypertensives might have the unanticipated effects of changing brain function and causing mental fatigue," said Jennings.
