Early Alzheimer's Linked to Brain 'Leakage' | WPN World People News

People in the early stages of Alzheimer's disease may have more "leaks" in the barrier that separates the brain from the bloodstream, a small study suggests.

Known as the blood-brain barrier, it's made up of tightly joined cells that line blood vessels in the brain. They form a filtration system that allows certain essential substances -- such as water and sugar -- into the brain, while keeping potentially damaging substances out.

The new study adds to evidence that leaks in the blood-brain barrier are detectable in Alzheimer's patients.

But it's not clear what it all means.

"They don't know whether this leakage is a result of the disease, or a cause of it," said expert.

It's also unclear exactly what is happening in the leaky areas spotted on patients' brain scans, according to expert.

In theory, expert said, the leaks could be opening the door for toxic substances to enter the brain -- but the study doesn't prove that.

Researchers know that the pathological brain changes associated with Alzheimer's begin at least 15 years before symptoms appear, Morgan explained.

First, there is an abnormal buildup of proteins called amyloid. There are no immediate symptoms because the brain is able to compensate for those protein deposits, expert said.

Eventually, though, another type of abnormality appears -- twisted fibers of a protein called tau. Symptoms typically arise not long afterward, according to expert.

So, the question is where in that sequence of events does brain leakage occur?

The findings are based on 16 patients who'd been diagnosed with early Alzheimer's disease, and 17 healthy adults the same age. The researchers used a special MRI technique to detect areas of brain leakage in each study participant.

In general, the investigators found that Alzheimer's patients showed more areas of leakage across the brain.

And, the more leakage the study participants had in the brain's gray matter, the worse they did on tests of memory and other mental abilities. (Gray matter basically acts as the brain's information-processing center.)

It's plausible, expert said, that a compromised blood-brain barrier could contribute to Alzheimer's -- by allowing certain cells from the bloodstream to "infiltrate" the brain and contribute to inflammation and nerve cell damage, for example.

If that's true, there is no obvious way to intervene.

But expert pointed to a possible "silver lining" in the leaky-brain situation. Normally, the blood-brain barrier blocks medications and other systemic therapies from getting into the brain.

"So if Alzheimer's patients do have a leaky blood-brain barrier, in a strange way, that could be a good thing," expert said. "Some therapies that are under development might have a better chance of working."

The researchers also raise the possibility that MRI scans could help diagnose Alzheimer's early, by detecting leaks.

But expert had doubts. For one, expert said, the researchers only reported on averages across the two study groups: If only some Alzheimer's patients show excess brain leakage, it would not be a reliable way to detect the disease.

Plus, expert said, it's possible that people with other forms of dementia, or other neurological diseases, may also have more leaks in the blood-brain barrier.

Source: U.S. Dept. of Health & Human Services