ST. PAUL, MN - People with high blood pressure are more likely to experience cognitive decline, or a loss in their ability to think, remember and learn, according to a study in the December 10 issue of Neurology, the scientific journal of the American Academy of Neurology.
The study followed 1,373 people age 59 to 71 in western France over four years. Participants' blood pressure and mental status were tested at the beginning of the study, after two years and after four years. At the beginning of the study, 167 people had high blood pressure; of those, 81 were taking medication to control their hypertension.
After four years, 21.7 percent of those with untreated high blood pressure experienced severe cognitive decline. Severe cognitive decline was defined as a drop of four or more points on a common cognitive test called the Mini Mental Status Examination. Of those with high blood pressure whose treatment didn't bring the blood pressure down to normal, 12.5 percent had severe cognitive decline. Of those with successfully treated high blood pressure, 7.8 percent had severe cognitive decline. And of those with normal blood pressure, only 7.3 percent had severe cognitive decline.
"People who experience severe cognitive decline are most likely to later develop Alzheimer's disease or other dementia," said neurologist and study author Christophe Tzourio, MD, PhD, of INSERM, the French national institute of health and medical research, in Paris. "Therefore, the question raised by these results is whether those with untreated and/or uncontrolled high blood pressure have a higher risk of dementia.
"This is a major issue. If high blood pressure and other vascular factors play a role in dementia, then it might be possible to prevent or delay the occurrence of this dreadful disease by controlling high blood pressure and other vascular factors. However, this issue is controversial among researchers. We only have indirect arguments for this relationship at this time, and more studies are needed to estimate how much of the risk of dementia is due to high blood pressure and other vascular factors."
Whether or not high blood pressure plays a role in dementia, the study shows that it may have a negative effect on people's mental abilities, Tzourio said.
"People with high blood pressure should be encouraged to get it under control in order to avoid this harmful effect," he said. "People who don1t know their blood pressure status should see their doctor to get it checked." The study was conducted under an agreement between INSERM and the Merck, Sharp and Dhome-Chibret Laboratories.
A neurologist is a medical doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system.
The American Academy of Neurology, an association of more than 16,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research.