Unlike Alzheimer’s disease which is still poorly understood, it’s well accepted that vascular dementia is caused by strokes, often a series of small, "silent" strokes. While early stage Alzheimer’s is characterized mostly by memory loss, vascular dementia more generally affects executive function, multi-tasking, problem-solving and reasoning. It’s important to understand that more than one type of dementia can be present, which can further complicate a diagnosis.
When people are having a major stroke, they are likely to be aware that something is happening that could cause significant damage unless immediate medical intervention is sought. However, the undiagnosed mini-strokes that can result in mild cognitive impairment leading to vascular dementia often occur without any immediate evidence that something is wrong.
"By age 63, one in 10 people have already had these tiny strokes," says Dr. Vladimir Hachinski, a clinical and research neurologist at the University of Western Ontario and an internationally recognized expert on stroke. "With each decade, the numbers go up. And people who have had silent strokes are more likely to have bigger strokes. For each stroke that is diagnosed, five more go undetected."
Now, according to an article on the Alzheimer’s Research Forum, mouse studies have shown that a drug given to people with early stage Alzheimer’s to slow their cognitive decline may benefit people prone to microinfarcts, also known as mini-strokes. The December 12th issue of the Journal of Neuroscience shows that neurons die considerably more slowly after mini-strokes than after large strokes, suggesting there might be time to intervene therapeutically. Maiken Nedergaard of the University of Rochester Medical Center, New York, led that study.
The time frame for the slower mini-strokes leaves a therapeutic window open for intervention. According to a study in Nature Neuroscience, memantine, a drug approved by the FDA for treating moderate to severe Alzheimer’s disease, has been used by researchers to see if the damage to brain processes during mini-strokes could be stopped or slowed down with the medication.
Researchers in a rat study led by David Kleinfeld, University of California, San Diego, induced clots in individual rats’ blood vessels. Those clots were enough to weaken the rats’ decision-making during a behavioral task. A shot of the Alzheimer’s drug memantine alleviated the cognitive defects and associated tissue damage. Though it is still not known if single clots would cause similar damage in people, the findings offer hope that the problems may be treatable.
While these studies are still in the small animal phase, since memantine is available for people with Alzheimer’s it wouldn’t be surprising to see human studies begin soon. I hope so. If scientists prove that this drug can save thousands of people yearly from permanent damage due to mini-strokes, we’ll have another powerful tool available for improving the quality of life for our aging population.
Landhuis, E. Alzheimer’s Research Forum ( 2012, December 21) Alzheimer’s Research Forum. Mini-Stroke Does Mega-Damage"”Can Memantine Help? Retrieved from http://www.alzforum.org/new/detail.asp?id=3358
Gerstel, J. (2011 February 23), "˜Slow and insidious’ mini strokes cause vascular dementia. Healthzone.ca. Retrieved from http://www.healthzone.ca/health/mindmood/brainhealth/article/943751—slow-and-insidious-mini-strokes-cause-vascular-dementia