Could a brain infection be behind an Alzheimer’s mystery?

When I had the pleasure of speaking with three of the world’s leading neuroscientists last week while I was filling in for Kerri Miller, they made a good point when telling me that we need to understand science research better, particularly the significance of small discoveries about how the brain works.

It’s easy to leap to great conclusions about small discoveries and hypotheses. We’re an impatient species and we have a tendency to want the “big picture” solved. But that’s not the way neuroscience works.

Today provides an example of why the field can be so exciting when people challenge what they think they know.

People who have Alzheimer’s have plaque throughout their brain. But why? Maybe fruit flies, yeast, roundworms, and mice hold a key.

The New York Times reports today that Harvard researchers are theorizing that the plaque is caused by infections in the brain.

The Harvard researchers report a scenario seemingly out of science fiction. A virus, fungus or bacterium gets into the brain, passing through a membrane — the blood-brain barrier — that becomes leaky as people age. The brain’s defense system rushes in to stop the invader by making a sticky cage out of proteins, called beta amyloid. The microbe, like a fly in a spider web, becomes trapped in the cage and dies. What is left behind is the cage — a plaque that is the unique hallmark of Alzheimer’s.

What makes neurology so exciting? These small amounts of research and a neuroscientist who wonders “what if?”

The work began when Robert D. Moir, an assistant professor of neurology at Harvard Medical School, had an idea about the function of amyloid proteins, normal brain proteins whose role had long been a mystery.

The proteins were traditionally thought to be garbage that accumulates in the brain with age. But Dr. Moir noticed that they looked a lot like proteins of the innate immune system, a primitive system that is the body’s first line of defense against infections.

Elsewhere in the body, such proteins trap microbes — viruses, fungi, yeast and bacteria. Then white blood cells come by and clear up the mess. Perhaps amyloid was part of this system, Dr. Moir thought.

Why hadn’t someone asked “what if?” before? The Times says researchers have fixated on the idea of plaque as trash that accumulated in the brain, that few had asked if there might be something else going on.

Who knows whether any of this will pan out. The maddening nature of the neuroscience business is there’s a long way to go to prove a small sliver of knowledge.

Science is awesome that way.

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