By discovering the culprit behind the decrease in blood flow in the brains of people with Alzheimer's, Cornell University's biomedical engineers have made possible new promising therapies for the disease.
Do you know that vertigo gives you when, after lying down for a prolonged period, you get up a little too fast?
That sensation is caused by a sudden reduction in blood flow to the brain, a reduction of about 30 percent. Now imagine living every minute of every day with that level of decreased blood flow.
People with Alzheimer's disease should not imagine it. The existence of cerebral blood flow reduction in patients with Alzheimer's disease has been known for decades, but the exact correlation with impaired cognitive function is less understandable.
"People probably adapt to decreasing blood flow, so they do not experience vertigo of time, but there is clear evidence that impacts cognitive function," said Chris Schaffer, an associate professor of biomedical engineering at Cornell University.
A new study from the joint laboratory of Schaffer and associate professor Nozomi Nishimura, offers an explanation for this dramatic decrease in blood flow: white blood cells attached to the inside of the capillaries, the smallest blood vessels in the brain. And while only a small percentage of capillaries undergo this blockage, each stalled vessel leads to a decrease in blood flow in several downstream vessels, amplifying the impact on the overall cerebral blood flow.
Their card "The adhesion of neutrophils in the brain capillaries reduces cortical blood flow" and alters the function of memory in Alzheimer's models ", published in Nature Neuroscience . [1
The paper, said Schaffer, is the point of arrival of about a decade of studies, data collection and analysis.It began with a study in which Nishimura was trying to put clots in the vasculature of the Alzheimer's brain to see their effect.
"It turns out that … the blocks we were trying to induce were already there, "she said." She turned the search around – this is a phenomenon that was already happening. "
Recent studies suggest that blood flow deficits cer They are one of the first detectable symptoms of dementia.
"What we did is identify the cellular mechanism that causes reduced blood flow in the brain in Alzheimer's disease models, which are neutrophils [white blood cells] that stick to the capillaries," Schaffer said. "We have shown that when we block the cellular mechanism [that causes the stalls] we get an improved blood flow, and associated with that improvement in blood flow is immediate restoration of the cognitive performance of spatial and work memory tasks."
"Now that we know the cellular mechanism," he said, "it's a much closer path to identify the drug or the therapeutic approach to treat it."
The team identified about 20 drugs, many of the which have already been approved by the FDA for human use, which have potential in the treatment of dementia and are examining these drugs in Alzheimer's mice.
Schaffer said it was "super-optimistic" that if the same capillary blocking mechanism is at play in humans as in mice, this line of research "could be a complete game change for people with the disease of Alzheimer's ".
The study found that exercise is good for the brain, modifies blood flow in the elderly
Jean C. Cruz Hernández et al., Neutrophil adhesion in brain capillaries reduces cortical blood flow and alters memory function in mouse models of Alzheimer's disease, Nature Neuroscience (2019). DOI: 10.1038 / s41593-018-0329-4
Researchers closer to new Alzheimer's therapy with discovery of cerebral blood flow (2019, 11 February)
recovered on 12 February 2019
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