Hypertension predicts progression to dementia in elderly with executive dysfunction but not memory dysfunction. Control of hypertension could prevent progression to dementia in one-third of the subjects, say Canadian researchers.
Executive functions involve (at the very least):
Advertisementplanning for the future
the ability to inhibit or delay responding
initiating behavior, and
shifting between activities flexibly
When a person's ability on those fronts is impaired, they are supposed to suffer from executive dysfunction.
Midlife hypertension has long been established as a risk factor for dementia, but the role of late-life hypertension remains unclear.
Shahram Oveisgharan, of University of Western Ontario, Canada, and Isfahan University of Medical Sciences, Isfahan, Iran, and Vladimir Hachinski, also of University of Western Ontario, set out to investigate the role of hypertension in cognitive deterioration among older subjects with cognitive impairment, but no dementia.
The Canadian Study of Health and Aging was conducted in 3 waves (1991, 1995-1996, and 2001-2002). It was a community-based cohort study. A cohort Study is a study in which subjects who presently have a certain condition and/or receive a particular treatment are followed over time and compared with another group who are not affected by the condition under investigation.
The researchers studied 990 subjects with a mean age of 83.06 (6.97) years having cognitive impairment, no dementia who were followed up for 5 years in the Canadian Study of Health and Aging.
Over the follow-up period, dementia developed at approximately the same rate among participants with and without hypertension (59.5 percent of individuals with high blood pressure vs. 64.2 percent of those without). A similar pattern was observed among those with memory dysfunction alone and with both memory and executive dysfunction. However, among patients with executive dysfunction only, presence of hypertension was associated with an increased risk of developing dementia (57.7 percent of those with high blood pressure progressed to dementia, vs. 28 percent of those without).
"We show herein that the presence of hypertension predicts progression to dementia in a subgroup of about one-third of subjects with cognitive impairment, no dementia," they conclude. "Control of hypertension in this population could decrease by one-half the projected 50-percent five-year rate of progression to dementia."
"This study may have profound implications for community dwellers with cognitive impairment, no dementia," the authors write. "Worldwide, neurologic disorders are the most frequent cause of disability-adjusted life years; among these, cerebrovascular disease is the most common risk factor, and dementia is the second most common. There is no preventive or therapeutic intervention to mitigate this public health burden."
The findings are published in the February issue ofArchives of Neurology, one of the JAMA/Archives journals.