12 November 2010
Researcher Owen Carmichael says most people develop vascular disease as they age, which affects blood flow to the brain.
Researchers have identified a link between dementia and the brain damage that can occur in older people with high blood pressure and other forms of cardiovascular disease.
High blood pressure, high cholesterol, and other conditions that affect blood flow don't have obvious symptoms, which is why they are sometimes described as silent vascular disease. But researcher Owen Carmichael at the University of California-Davis says most people develop vascular disease as they age, and it affects blood flow to the brain.
"Vascular disease is so widespread, and such a small amount of it can affect your ability to think, that it's almost — I don't want to use the word 'ubiquitous,' but it's very, very common in the elderly," he said.
Carmichael is lead author of a new study that found people with brain damage caused by this silent vascular disease are more likely to show a faster decline in memory and thinking ability — cognitive impairment.
Study participants were given MRI scans to identify damaged brain tissue that was, in effect, starved when the blood vessels couldn't provide enough nutrients. They were also given tests to evaluate any change in their cognitive abilities over three years.
Although people with damage to the brain tissue called white matter are more likely to have dementia, Carmichael stops short of saying that the brain damage actually causes the dementia.
"Many different things are going on in the brains of people who are aging. So cognitive problems in late in life are not like cancer or HIV, where there's basically one big biological problem going on. There's actually many different things going on at the same time."
And he says it's up to researchers to figure out how those factors interact to cause the decline in memory, thinking, and other skills that are seen in dementia.
"If you walked in on day one and you seemed to have a great deal of this white matter damage, then you tended to do worse over the course of a year in terms of your ability to think," he said.
Carmichael says for now this is just a research finding, not the basis for screening patients to see if they have a higher chance of developing dementia. But he says it does underscore the importance of cardiovascular health for keeping the brain, as well as the heart, healthy.
He says there's no treatment for Alzheimer's Disease, one feared cause of dementia.
"But now, if vascular problems are also affecting your ability to think over time, we have gobs of treatments for that. There are all sorts of different things you can do to help your blood flow. So treating the vascular disease might actually, in the long term, help your process of cognitive aging."
Owen Carmichael describes the results of this study in the Archives of Neurology, a journal published by the American Medical Association.