Several neurovascular measurements of the brain such as blood flow and the ability to compensate for the lack of it are better predictors of mild cognitive impairments than risk factors such as high cholesterol and hypertension, according to a new study published in Alzheimer’s & Dementia, a journal of the Alzheimer’s Association from the University of Oklahoma.
Currently, estimates are that 18% of the global population has mild cognitive impairment, of which 10-15% will go on to develop dementia. This number is projected to affect over 152 million people by 2050, reflecting the urgent need to find prospects of preventing or treating memory problems early before they progress to dementia.
“People with mild cognitive impairment are at highest risk for the next step, which is dementia,” said Calin Prodan, M.D., a professor of neurology in the OU College of Medicine and a co-author of the paper. “We’re trying to decipher the ‘fingerprints’ of mild cognitive impairment — what happens to the brain when a person moves from healthy aging to mild cognitive impairment, and is there something we can do to intervene and prevent the decline to dementia?”
Focusing on vasculature
This research focused on the brain’s vasculature, the network of blood vessels, and how it acts differently in older people with mild cognitive impairment. It looked at several types of neurovascular brain measurements at three stages of life: young adults, older adults with aging but healthy brains, and older adults with mild cognitive impairment. Each group of participants played short memory games on a computer while wearing a cap with light sensors; the technology is called functional near-infrared spectroscopy, which measured blood flow in the brain as participants were challenged to memorize increasingly larger sequences of letters.
Neurovascular compensation
According to the researchers, blood flow increased in the brains of young adults to provide their brains with the energy needed to meet the needs of playing the game, which is called neurovascular coupling. In older healthy aging brains, the blood flow did not increase as much, but the brain compensated by engaging other regions to help with the challenges, which is called functional connectivity. However, in those with mild cognitive impairment blood flow was greatly reduced and they lost the neurovascular ability to compensate by the brain recruiting other areas to help.
“People with mild cognitive impairment have lost that compensation mechanism. There is a drastic change in brain activity in those with mild cognitive impairment,” said Cameron Owens, Ph.D., lead author of the study. After earning his doctorate, Owens is now in his third year of medical school as part of the OU College of Medicine’s M.D./Ph.D. degree program.
Cerebrovascular endothelial extracellular vesicles
Liquid biopsy assessments provided another neurovascular window into mild cognitive impairment, measuring the amount of cerebrovascular endothelial extracellular vesicles (CEEVs), which are tiny particles released from the cells lining the brain’s blood vessels. When the inner lining of blood vessels is damaged, it secretes CEEVs, and those with mild cognitive impairment were found to have more CEEVs in their brains than those with healthy aging brains. MRI images confirmed that those with higher levels of CEEVs also had more ischemic damage, meaning the small vessels in their brains did not receive adequate blood supply.
“Every brain is different, and there may be differing reasons for cognitive impairment, but having these predictors — measuring neurovascular coupling, functional connectivity, and CEEVs — potentially opens opportunities to develop individualized interventions, whether it’s a pharmacological therapy or non-invasive brain stimulation, or something as simple as cognitive behavioral therapy,” said Andriy Yabluchanskiy, Ph.D., OU College of Medicine associate professor of neurosurgery and co-author of the study.
Ongoing research
Moving forward, additional research will continue to explore several different neurovascular angles to further analyze CEEVs, which are thought to carry cargo and could be contributing to cognitive impairment.
“We are in year two of a four-year study,” Yabluchanskiy said. “This is a prospective study in which all of our participants are living right here in Oklahoma.”
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References/Sources/Materials provided by:
http://dx.doi.org/10.1002/alz.14072
https://worldhealth.net/news/brain-training-slows-cognitive-decline/
