מתוך medicontext.co.il
By Peggy Peck
CHICAGO (Reuters Health) – Positron emission tomography (PET) scans show that hypertension causes changes in brain blood flow that affect short-term memory, according to findings presented at the American Heart Association's 55th Annual Fall Conference of the Council for High Blood Pressure Research.
Dr. J. Richard Jennings, of the University of Pittsburgh and Western Psychiatric Institute, and colleagues conducted PET scans on 33 hypertensive patients and 62 normotensive controls. Patients and controls ranged in age from 50 to 70. The hypertensive patients were unmedicated and had no history of stroke.
Hypertensive patients who had measurable working memory impairment, as measured with a series of neuropsychological assessments, "had significantly less blood flow in prefrontal and parietal areas compared to normotensive controls," Dr. Jennings said.
"Our hypothesis was that the brain of hypertensive patients has to adjust to blood flow," he explained in an interview with Reuters Health. In hypertensive patients some blood vessels undergo endothelial remodeling, so blood flow to those areas of the brain is diminished, he said. "We thought we might see increased blood flow to contralateral areas that are compensating by performing the task of the areas that receive less blood flow," he said.
He said that analysis of the PET scans did indicate an increase in left hemisphere blood flow among hypertensives who have memory loss. That compensation, according to Dr. Jennings, may explain the slight memory loss. "Other regions are compensating but they are doing it in a slightly less efficient way," he said. Thus, memory changes are "very slight, similar to the type of difference you might see between a healthy 45-year-old and a 55-year-old."
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