Alzheimer’s: blood oxygen levels could explain why memory loss is an early symptom
University of Sussex
Highlights
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In a world first, scientists at the University of Sussex recorded blood oxygen levels in the hippocampus and provided experimental evidence of why the area, commonly known as ’the memory center of the brain’, is vulnerable to damage and degeneration, a precursor to Alzheimer’s disease. disease.
To understand why this region is so sensitive, researchers at the University of Sussex, led by Dr Catherine Hall from the Sussex School of Psychology and Neuroscience, studied brain activity and blood flow in the hippocampus of mice. The researchers then used simulations to predict that the amount of oxygen delivered to hippocampal neurons furthest from blood vessels is only enough to keep the cells functioning normally.
Dr Catherine Hall, senior lecturer in psychology at the University of Sussex, says: "These findings are an important step in the search for preventive measures and treatments for Alzheimer’s disease, because they suggest that increasing blood flow in the hippocampus could be truly effective in preventing damage from occurring.
"If it is right that increasing blood flow in the hippocampus is important for protecting the brain from diseases such as Alzheimer’s, then more emphasis will be placed on the importance of regular exercise and a low-cholesterol diet for long-term brain health.
"We think the hippocampus exists at a tipping point. Normally it’s fine, but when anything else happens that decreases cerebral blood flow, the oxygen levels in the hippocampus are reduced to levels that stop neurons from functioning. We think that This is probably why Alzheimer’s disease first causes memory problems: because the early decrease in blood flow prevents the hippocampus from functioning properly.
"The same factors that put you at risk for a heart attack make you more likely to develop dementia. That’s because our brain needs enough blood flow to provide energy, in the form of oxygen and glucose, so that brain cells can function properly and because blood flow can remove waste products such as amyloid beta proteins that build up in Alzheimer’s disease.
"Now we want to find out if lower blood flow and oxygen levels in the hippocampus are what cause amyloid beta to start accumulating in Alzheimer’s disease. Understanding what causes the early damage will be really important in helping us learn how to treat or prevent disease."
Dr Kira Shaw, a psychology researcher at the University of Sussex who carried out the main experiments, reported:
"We found that blood flow and oxygen levels in the hippocampus were lower than those in the visual cortex. Additionally, when neurons are active, there is a large increase in blood flow and oxygen levels in the visual cortex. "This provides energy to hungry neurons . But in the hippocampus, these responses were much smaller."
The scientists also found that hippocampal blood vessels contained fewer mRNA transcripts (codes for making proteins) for proteins that shape blood vessel dilation. Additionally, cells that dilate small blood vessels, called pericytes, were shaped differently in the hippocampus than in the visual cortex.
Dr. Shaw concluded: "We believe that blood vessels in the hippocampus are less able to dilate than those in the visual cortex."
