In Early Alzheimer’s Disease, Impaired Blood-Brain Barrier May Lead to Cognitive Decline, Researchers Say

Researchers at the Maastricht University Medical Center have investigated how the permeability of the blood-brain barrier (BBB) is involved in early forms of Alzheimer disease. The findings suggest that a faulty BBB may be involved in the initial pathologic process that eventually results in neurodegeneration and dementia in these patients.

Researchers believe that detecting blood-brain barrier leakage may lead to earlier diagnoses.

The research paper, “Blood-Brain Barrier Leakage in Patients with Early Alzheimer Disease,” was recently published in Radiology.

The blood-brain barrier, made up of specialized and tightly packed endothelial cells, forms a semi-permeable barrier that separates the brain from the circulatory system, protecting it from harmful pathogens and toxins while also regulating the delivery of nutrients and maintaining a balanced environment for the proper functioning of the central nervous system (CNS).

The team used dynamic contrast material-enhanced magnetic resonance imaging (MRI) to assess and compare the integrity of the blood-brain barrier of 16 early Alzheimer’s patients and 17 healthy age-matched controls. The scientists measured BBB leakage rates and determined the amount of the leaking brain tissue. Results show that blood-brain barrier leakage rate was significantly higher in Alzheimer’s patients compared with controls.

And, the leakage was present throughout the cerebrum, the largest part of the brain, and the patients presented a significantly higher leakage in the gray matter. Subtle blood-brain barrier impairment was also detected in the white matter.

Researchers then found that the extent of blood-brain barrier leakage was proportional to the decline of cognitive performance in Alzheimer’s patients, suggesting that an impaired BBB and consequent abnormal environment for nerve cells is part of the early pathology mechanisms that lead to the onset of Alzheimer’s, eventually resulting in cognitive decline and dementia.

Moreover, the addition of diabetes and other non-cerebral vascular diseases to the analysis model did not change the results, which strengthens the relationship between blood-brain barrier impairment and Alzheimer’s pathology.

“For Alzheimer’s research, this means that a novel tool has become available to study the contribution of blood-brain barrier impairment in the brain to disease onset and progression in early stages or pre-stages of dementia,” study author Dr. Walter H. Backes said in a news release.