If an elderly person suffers from high blood pressure (hypertension) he/she has a higher risk of experiencing thinking and learning difficulties (mild cognitive impairment), according to an article published in Archives of Neurology (JAMA/Archive), December issue.
The researchers wrote “Mild cognitive impairment has attracted increasing interest during the past years, particularly as a means of identifying the early stages of Alzheimer’s disease as a target for treatment and prevention.”
Approximately 9.9 out of every 1,000 elderly people who do not have dementia eventually develop some kind of mild cognitive impairment every year. 10-12% of these people go on to develop Alzheimer’s disease each year, compared to 1-2% of the general population.
Christiane Reitz, M.D., Ph.D., Columbia University Medical Center, New York and team collected data on 918 Medicare recipients from 1992 through to 1994, average age 76.3 – none of them had mild cognitive impairment at the beginning of the study. All of them had an initial interview and physical examination. They also had a cognitive function test. They were followed-up every 18 months for 4.7 years (average). Those who went on to develop mild cognitive impairment had low cognitive scores and difficulties with memory – however, they were still able to carry out their normal daily activities; none of them were diagnosed with dementia.
During the 4.7-year follow-up period, 334 of them developed mild cognitive impairment (MCI), 160 of whom had amnestic* mild cognitive impairment, and 174 had non-amnestic* mild cognitive impairment.
* With amnestic mild cognitive impairment there is significant memory loss, while with non-amnestic mild cognitive impairment there isn’t.
High blood pressure appears to be linked to a raised risk of mild cognitive impairment.
The researchers wrote “The mechanisms by which blood pressure affects the risk of cognitive impairment or dementia remain unclear. Hypertension may cause cognitive impairment through cerebrovascular disease. Hypertension is a risk factor for subcortical white matter lesions found commonly in Alzheimer’s disease. Hypertension may also contribute to a blood-brain barrier dysfunction, which has been suggested to be involved in the cause of Alzheimer’s disease. Other possible explanations for the association are shared risk factors,” such as the formation of free radicals, which damage cells.
They concluded “Our findings support the hypothesis that hypertension increases the risk of incident mild cognitive impairment, especially non-amnestic mild cognitive impairment. Preventing and treating hypertension may have an important impact in lowering the risk of cognitive impairment.”
“Hypertension and the Risk of Mild Cognitive Impairment”
Christiane Reitz, MD, PhD; Ming-Xin Tang, PhD; Jennifer Manly, PhD; Richard Mayeux, MD, MSc; José A. Luchsinger, MD, MPH
Arch Neurol. 2007;64(12):1734-1740.
Written by – Christian Nordqvist