Netherlands – Alzheimer’s disease an impaired function of the blood-brain barrier seems to play a central role. Already at the beginning of the neurodegenerative disease this vital barrier leaks, which selectively protects the brain against unwanted substances such as pathogens and toxins.

Evidence found by Dutch researchers in a small study, published in the journal Radiology, compared the function of the blood-brain barrier of Alzheimer’s patients in the early stage of the disease using a special magnetic resonance imaging with the healthy peers. They found out that the blood-brain barrier was affected as well as the signs of cognitive disabilities and dementias were clearer.

“A leaky blood-brain barrier means that the brain has lost its protection capabilities,” explains Walter H. Backes of the University of Maastricht. “The stability of brain cells is disturbed and the environment, in which the brain cells react with each other, is in a poor state.”

This could in turn lead to malfunctions in the brain, according to the first author of the study, Harm J. van de Haar. The blood-brain barrier separates the bloodstream from the central nervous system.This barrier ensures highly specialized active as passive transport and filtering mechanisms that the brain with sufficient nutrients is powered and can dispose of waste materials, but is protected from harmful influences such as neuro toxins or pathogens. A functional blood-brain barrier is therefore essential for a healthy brain.

Already earlier studies had have suggested that an increased permeability of the blood-brain barrier is important in Alzheimer’s. Thereby, the researchers looked into histological studies of brain tissue and blood analyses. Backes and his colleagues took a direct look at the function of the blood-brain barrier in the living organism using contrast-based magnetic resonance imaging. In 16 patients, who were diagnosed with incipient Alzheimer’s disease, as well as to 17 healthy subjects of comparable age, they measured the rate of the leak and created map where the leaks in the barrier were recorded.

In fact, the researchers found, in patients with incipient Alzheimer’s, significantly more places in the brain tissue which showed signs of a leaky blood-brain barrier. This was in particular on the so-called grey matter, the part of the brain, which mainly contains cell bodies. Similar changes in the so-called white matters, which mainly consists of nerve fibers in contrast to the gray matter, were also present, but less clear.

Depending on the leaks in the area of gray matter were pronounced, the worse the patient’s mental performance was.

Therefore the researchers concluded that a damaged blood-brain barrier is part of the early course of the disease of Alzheimer’s disease and suggested it is part of a series of events that eventually lead to mental decline and dementia.