Blood-Brain Barrier Test May Predict Dementia
Millions of people in the United States show some sort of cognitive impairment, placing them at higher risk for developing dementia. Alzheimer's disease is the most common dementia diagnosis.
Researchers have been looking for ways to test for early signs of cognitive impairment and dementia. Early detection could open the door to strategies that prevent disease progression. Potential biomarkers include changes in the size and function of the brain and its parts, as well as levels of certain proteins seen on brain scans, in cerebrospinal fluid, and in blood.
People with Alzheimer's disease, for example, have abnormally high levels of plaques made up of beta-amyloid and tangles made of tau proteins.
To look for earlier biomarkers of cognitive decline, researchers examined two markers involved in the breakdown of the blood-brain barrier. This barrier controls the movement of cells and molecules between the blood and the fluid that surrounds the brain's nerve cells. Past studies found abnormalities in the capillaries of the brain often contribute to dementia.
The team enrolled more than 160 people with and without cognitive impairment. They measured levels of the soluble form of a protein called platelet-derived growth factor receptor beta (PDGFRβ). PDGFRβ is found in the capillaries that maintain the blood-brain barrier's integrity.
Levels of the soluble form rise in cerebrospinal fluid when the blood-brain barrier is compromised. The team also tracked the integrity of the blood-brain barrier in 73 participants using an MRI-based technique they previously developed.
The study was supported in part by NIH's National Institute on Aging (NIA) and National Institute of Neurological Disorders and Stroke (NINDS). Results were published online on January 14, 2018, in Nature Medicine.
The researchers found that, compared with those without cognitive impairment, those with cognitive impairment had higher levels of soluble PDGFRβ and a greater breakdown in the blood-brain barrier of certain brain regions. Notably, both these measures were independent of beta-amyloid and tau protein levels.
The findings suggest these measurements could pave the way for an early diagnostic test for cognitive impairment from Alzheimer's disease as well as other causes.
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