Study finds leaks in brains of patients with early Alzheimer’s disease

A small study has found leaks in the blood-brain barrier in patients with Alzheimer’s. The barrier made of small adjoined cells that line blood vessels in the brain separate brain from the bloodstream. The study suggested that leaks in the barrier have something to do with the disease in people, but it neither confirms the leaks cause Alzheimer’s, nor that it is a result of the condition. However, the study said that patients with early stages of Alzheimer’s disease may have more leaks.

The barrier works as a filtration system that prevents potentially damaging substances from entering into the brain and allows certain essential substances, such as water and sugar, to pass. The study also did not find how those leaks may be reacting.

According to Dr. Ezriel Kornel, an assistant clinical professor of neurological surgery at Weill Cornell Medical College, in New York City, the leaks could be letting toxic substances to enter the brain.

The pathological brain changes linked to Alzheimer’s start coming up around 15 years before the symptoms of the disease become evident. At first, proteins, called amyloid, build up in the brain with no symptoms. Other changes in the brain occur that lead to twisted fibers of a protein called tau. The symptoms arrive soon after the latter changes.

This small study was conducted on 16 patients, who had been diagnosed with early Alzheimer’s disease, and also on 17 healthy adults. Walter Backes and colleagues at Maastricht University, in the Netherlands, used a special MRI technique to detect areas of brain leakage in each study participant.

They found that Alzheimer’s patients had more areas of leakage across the brain than the healthy group. In the study, more leakage in the brain’s gray matter meant worse the participants did on tests of memory and other mental abilities.

A report published in Huffington Post revealed, “Researchers have long believed that the devastating protein plaques that collect in the brains of people with Alzheimer’s disease have no useful function, and their presence does nothing but obliterate once vital memories and minds.”

A study published this week in the journal Science Translational Medicine suggests that the plaques — made of a protein called amyloid beta — may actually have a role after all, possibly in fighting off infection, and that Alzheimer’s may be an unwelcome result of this legitimate purpose.

“It’s intriguing, it’s exciting, and it opens new opportunities for intervening in the disease, but at the same time it’s very preliminary and speculative,” says Ronald Petersen, MD, Ph.D., director of the Mayo Clinic Alzheimer’s Disease Research Center in Rochester, Minnesota. “I wouldn’t go too far in saying that this is the answer or breakthrough.”

“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,” according to a news report published by Journal Star.

It’s also unclear exactly what is happening in the leaky areas spotted on patients’ brain scans, according to Kornel, who wasn’t involved in the study. In theory, he said, the leaks could be opening the door for toxic substances to enter the brain — but the study doesn’t prove that.

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

According to a story published on the topic by Forbes, “But those who carry just one copy are resistant to malaria and similar protozoa. As a result, instead of gradually disappearing from the human gene pool, the variant has spread widely among populations from tropical areas who are most at risk of catching the parasites.”

The first defense against such infections is the blood-brain barrier, which allows the passage of essential molecules into the fluid that surrounds neurons but blocks most other substances. As we age, this protection weakens. Post-mortem examinations show that older people are more likely to have microbes in the brain than those who die young.

The idea that Alzheimer’s could be a reaction to these infections is also supported by the fact that it is often associated with inflammation, an immune system response. But the main evidence comes from new research showing what the beta-amyloid plaques associated with the disease are actually doing.

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