White Matter Stroke: How The Brain Stimulates Functional Recovery

The brain can be repaired, and brain function can be recovered, after a stroke in animals, UCLA researchers showed in a new study. The finding could have important implications for treating a condition known as a white matter stroke, a major cause of dementia.

Senior author of the study Dr. Thomas Carmichael, professor of neurology at the David Geffen School of Medicine at UCLA, said:

“Despite how common and devastating white matter stroke is there has been little understanding of how the brain responds and if it can recover. By studying the mechanisms and limitations of brain repair in this type of stroke, we will be able to identify new therapies to prevent disease progression and enhance recovery.”

White Matter Stroke

White matter stroke is a type of ischemic stroke, in which a blood vessel carrying oxygen to the brain is blocked.

Unlike large artery blockages or transient ischemic attacks, individual white matter strokes, which occur in tiny blood vessels deep within the brain, typically go unnoticed but accumulate over time. They accelerate Alzheimer’s disease due to damage done to areas of the brain involved in memory, planning, walking and problem-solving.

In a five-year study, Carmichael’s team looked at white matter strokes in animals and found that the brain initiated repair by sending replacement cells to the site, but then the process stalled. The team had a short list of molecular suspects from previous research that they thought might be responsible.

Researchers identified a molecular receptor as the likely culprit in stalling the repair; when they blocked the receptor, the animals began to recover from the stroke.

Around 795,000 suffer a stroke in the United States per year, resulting in nearly 130,000 deaths. Multiply the number of strokes by six, and you’ll have an estimate of the number of strokes that are “silent,” in that they do not produce symptoms that lead to hospitalization. Most of these silent strokes are white matter strokes.

Elif G. Sozmen et al.
Nogo receptor blockade overcomes remyelination failure after white matter stroke and stimulates functional recovery in aged mice
Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1615322113

Image: Cells in various stages of maturity: immature cells are green, more mature cells are red and fully mature cells are orange. Credit: University of California, Los Angeles

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