Summary: The new study found that whole blood exchange helped a mouse model of Alzheimer’s disease. Swapping in the blood of normal, healthy mice significantly reduced the formation of amyloid plaques in the brain. It also improved memory. The exact mechanism is unclear. The researchers suggest it may involve amyloid-beta moving from the brain to the blood. The findings suggest there may be a target for treating Alzheimer’s disease in the bloodstream (the peripheral circulation). That could open new ways to treat it.
Alzheimer’s is now among the top ten causes of disability and early death in the US. Sadly, it has also puzzled researchers for a long time. More than 100 years of hard research have failed to produce an effective treatment. Of course, there are medications that may give some relief and reduce the severity of the condition. Still, there isn’t any medical treatment that may significantly change the course of the disease. Even the latest drug, Leqembi (lecanemab-irmb), has become a subject of dispute because its benefits are limited. The US FDA approved it in 2022.
Even more worrying, science does not fully understand what causes the disease or how it progresses. All researchers know is that faulty or misfolded amyloid protein builds up in brain cells. Many factors drive it. More of this protein speeds up the death of brain cells. This loss of brain cells causes a steady decline in thinking and memory (cognition). So most treatments today focus on reducing the buildup of amyloid proteins in the brain. Studies suggest that reducing amyloid buildup may slow the disease.
One way to reduce these faulty proteins is to clean the blood, or remove certain toxins from it. Well-known methods include plasmapheresis or regular blood dialysis. Now a new study shows that this simple method may help slow Alzheimer’s considerably. In the new study, researchers looked at a mouse model of Alzheimer’s disease (AD) with a high level of a protein called amyloid-beta (Aβ) in the brain. This protein is believed to play a significant role in how AD develops. They exchanged the whole blood of the mice with AD for blood from normal, healthy mice. This significantly reduced the formation of amyloid plaques in the brain, by 40-80%. The drop in plaques also led to better spatial memory in the mice with AD. The researchers are not sure exactly how the blood exchange reduces the plaques and improves memory. They think it may have something to do with Aβ moving from the brain to the blood. This suggests there may be a target for treating AD in the bloodstream. That could lead to new ways to treat the disease. This study is just a proof of concept, but it points future studies in an exciting direction.
Until now, studies have focused heavily on clearing amyloid protein from the brain or slowing its buildup. But they have faced one major barrier: the blood-brain barrier. Many drugs simply cannot enter the brain in large enough amounts to work. Also, trying to reduce amyloid protein in the brain has not produced good results. This new study shows that researchers might have been working in the wrong direction. Instead of the brain, they need to focus on the blood. They need to find factors in the blood that lead to amyloid buildup in the brain. Or factors in the blood that might help clear amyloid already built up in the brain. Of course, one way whole blood exchange may work makes sense, since blood from healthy adults lacks certain factors that promote amyloid buildup.
Still, it is quite likely that these benefits may be due to other reasons. For example, other kinds of proteins, present or even absent in the whole blood, could be what helped the mice with Alzheimer’s.
Frequently asked questions
What is whole blood exchange for Alzheimer’s?
Whole blood exchange means replacing an animal’s blood with blood from a healthy donor. In this study, researchers swapped the blood of mice used as a model of Alzheimer’s disease for blood from normal, healthy mice. Amyloid plaque formation in the brain dropped by 40-80%, and the mice’s spatial memory improved. It is a proof of concept in mice, not yet a human treatment.
How could replacing blood reduce amyloid plaques in the brain?
The researchers are not sure yet. Their leading idea is that amyloid-beta moves out of the brain and into the blood. Another idea is that healthy blood lacks certain factors that promote amyloid buildup. It is also possible that other proteins, present or missing in the donor blood, are what helped the mice.
Is plasma exchange a treatment for Alzheimer’s?
Cleaning the blood is one way to lower the load of faulty proteins. Well-known methods include plasmapheresis or regular blood dialysis. This study suggests that approach may help slow Alzheimer’s, but the evidence here comes from mice. What it changes is the target. The bloodstream, not just the brain, becomes a place to treat the disease.
What is the newest drug for Alzheimer’s disease?
One of the latest is Leqembi (lecanemab-irmb), approved by the US FDA. It has become controversial because its benefits are limited. Current medications can ease symptoms and reduce severity. But no medical treatment yet significantly changes the course of the disease. That is why researchers are looking at new directions such as the blood.
Why has Alzheimer’s been so hard to treat?
More than 100 years of research have not produced an effective treatment. Science still does not fully understand what causes the disease or how it progresses. Most treatments try to reduce misfolded amyloid protein in the brain. But the blood-brain barrier keeps many drugs from reaching the brain in useful amounts. And lowering brain amyloid has not produced satisfying results.
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