Leaky brain capillaries and cognitive dysfunction linked, regardless of amyloid plaques, shows new USC research published in Nature Medicine.
The number of Americans with Alzheimer's is expected to more than double to about 14 million in 40 years, according to the Centers for Disease Control and Prevention. There are currently five Alzheimer's drugs approved by the U.S. Food and Drug Administration that temporarily help with memory and thinking problems, but none that treat the underlying cause of the disease or slow its progression. Researchers believe that successful treatment will eventually involve a combination of drugs aimed at multiple targets.
Alzheimers Disease
Alzheimer''s disease is a progressive neurodegenerative disease affecting memory and thinking and making the person increasingly dependent on others.
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‘The study findings could help with earlier diagnosis and suggest new targets for drugs that could slow down or prevent the onset of dementia.’
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USC's five-year study, which involved 161 older adults, showed that people with the worst memory problems also had the most leakage in their brain's blood vessels - regardless of whether abnormal proteins amyloid and tau were present.
"The fact that we're seeing the blood vessels leaking, independent of tau and independent of amyloid, when people have cognitive impairment on a mild level, suggests it could be a totally separate process or a very early process," said senior author Berislav Zlokovic, director of the Zilkha Neurogenetic Institute at the Keck School of Medicine of USC. "That was surprising that this blood-brain barrier breakdown is occurring independently."
![Genetics of Alzheimer´s disease]( "Genetics of Alzheimer´s disease")
There are numerous genes that have been discovered that are associated with Alzheimer's disease and indicate increased risk, aiding genetic counseling and better care.
In healthy brains, the cells that make up blood vessels fit together so tightly they form a barrier that keeps stray cells, pathogens, metals and other unhealthy substances from reaching brain tissue. Scientists call this the blood-brain barrier. In some aging brains, the seams between cells loosen, and the blood vessels become permeable.
"If the blood-brain barrier is not working properly, then there is the potential for damage," said co-authorArthur Toga, director of the USC Stevens Neuroimaging and Informatics Institute at the Keck School of Medicine. "It suggests the vessels aren't properly providing the nutrients and blood flow that the neurons need. And you have the possibility of toxic proteins getting in." Participants in the study had their memory and thinking ability assessed through a series of tasks and tests, resulting in measures of cognitive function and a "clinical dementia rating score." Individuals diagnosed with disorders that might account for cognitive impairment were excluded. The researchers used neuroimaging and cerebral spinal fluid analysis to measure the permeability, or leakiness, of capillaries serving the brain's hippocampus, and found a strong correlation between impairment and leakage.
"The results were really kind of eye-opening," said first author Daniel Nation, an assistant professor of psychology at the USC Dornsife College of Letters, Arts and Sciences. "It didn't matter whether people had amyloid or tau pathology; they still had cognitive impairment." The researchers cautioned that their findings represent a snapshot in time. In future studies, they hope to get a better sense of how soon cognitive problems occur after blood vessel damage appears. Zlokovic said it's unlikely that scientists will soon abandon amyloid and tau as Alzheimer's biomarkers, "but we should be adding some vascular biomarkers to our toolkit."
Source: Eurekalert
Genetics of Alzheimer´s disease
There are numerous genes that have been discovered that are associated with Alzheimer's disease and indicate increased risk, aiding genetic counseling and better care.
Advertisement
In healthy brains, the cells that make up blood vessels fit together so tightly they form a barrier that keeps stray cells, pathogens, metals and other unhealthy substances from reaching brain tissue. Scientists call this the blood-brain barrier. In some aging brains, the seams between cells loosen, and the blood vessels become permeable.
"If the blood-brain barrier is not working properly, then there is the potential for damage," said co-authorArthur Toga, director of the USC Stevens Neuroimaging and Informatics Institute at the Keck School of Medicine. "It suggests the vessels aren't properly providing the nutrients and blood flow that the neurons need. And you have the possibility of toxic proteins getting in." Participants in the study had their memory and thinking ability assessed through a series of tasks and tests, resulting in measures of cognitive function and a "clinical dementia rating score." Individuals diagnosed with disorders that might account for cognitive impairment were excluded. The researchers used neuroimaging and cerebral spinal fluid analysis to measure the permeability, or leakiness, of capillaries serving the brain's hippocampus, and found a strong correlation between impairment and leakage.
"The results were really kind of eye-opening," said first author Daniel Nation, an assistant professor of psychology at the USC Dornsife College of Letters, Arts and Sciences. "It didn't matter whether people had amyloid or tau pathology; they still had cognitive impairment." The researchers cautioned that their findings represent a snapshot in time. In future studies, they hope to get a better sense of how soon cognitive problems occur after blood vessel damage appears. Zlokovic said it's unlikely that scientists will soon abandon amyloid and tau as Alzheimer's biomarkers, "but we should be adding some vascular biomarkers to our toolkit."
Source: Eurekalert
Test Your Knowledge on Dementia
Dementia is a leading cause of disability in older people. It is a condition where brain cells are permanently damaged or functionally impaired. Till 2015, about 47.5 million people suffer from dementia across the globe. There are various conditions that lead to dementia and it is important to get aware of its causes, effects and vulnerability. So how much do you know dementia? Take our advanced q
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