Researchers show that even the smallest stroke can impair cognitive function

Even the smallest stroke can impair cognitive function

According to an article published in the online edition of Nature Neuroscience, the blockage even of the smallest blood vessels in the brain is associated with alterations in brain tissue, which may contribute to dementia onset. However, the study, conducted by researchers at the University of California, San Diego, showed that if these small changes are counteracted by the administration of a drug that is already in use, the installation of dementia can be delayed. Andy Y. Shih, lead author of the paper who completed this work as a postdoctoral fellow in physics at UC San Diego, revealed that the brain has a very rich blood supply and it is surprising that by blocking a blood vessel such consequences can occur.

Iimpair Cognitive Function

Shih and colleagues conducted experiments on animals and have revealed that even smallest blood clots can alter nerve tissue. They used laser light to clot blood in some vessels of the brain. After a week, they looked at those areas of the brain affected by blot clots and found that the damage was widespread. These micro-lesions are too small to be seen with magnetic resonance that has a resolution of 1 mm. In the brain, due to rich blood supply, in a square millimeter area  there are about a dozen of blood vessels. David Kleinfeld, professor of physics and Neurobiology, who leads the research group, was keen to point out that it is controversial whether such small lesions have an impact on brain function. But researchers did experiments in rats and showed that indeed these small lesions can alter the brain.

In addition, the researchers wanted to see if the damage to brain processes can be stopped or slowed down with medication. In this way they showed that memantine, a drug used to treat Alzheimer’s disease, may be useful in this regard. Memantine has been approved by the FDA for treating moderate to severe Alzheimer’s disease. Studies have shown that this drug, which works by blocking glutamate NMDA-type receptors, improves cognition in Alzheimer’s patients. Researchers at the University of California, San Diego, administered memantine to the rats affected by those small strokes and showed by experiments that this drug improves the cognitive function.

Patrick D. Lyden, a co-author of the study and chair of the department of neurology at Cedars-Sinai Medical Center in Los Angeles, said the study shows that even a small stroke can affect brain function. He said he suspects that these small stoke are among the contributing factors responsable for the occurrence of dementia and Alzheimer’s but that more studies are needed to confirm these facts.