Researchers say infections may cause Alzheimer’s

May 27, 2016 Providence Health Team

Does Alzheimer’s disease arise from the debris left by the brain’s own battles against infection?

It’s a startling new possibility raised by research published this week by Harvard Medical School and Massachusetts General Hospital. If the findings are confirmed by subsequent research, they may provide new avenues for researchers and health care providers to fight the ravages of Alzheimer’s, which causes loss of memory and cognitive processes, and behavioral changes.

More about Alzheimer’s

Alzheimer’s is a disease that attacks the brain, with symptoms developing slowly, then increasing over time. The most common early symptom, according to the Alzheimer’s Association, is difficulty remembering newly learned information.

Other symptoms include:

  • Disorientation
  • Mood changes
  • Behavior changes
  • Deepening confusion
  • Unfounded suspicions about other people
  • Difficulty speaking, swallowing and walking

For more information about Alzheimer’s, including the 10 warning signs, visit the Alzheimer’s Association website or the Providence health library.

New thinking about key protein

The study, published in Science Translational Medicine, found a naturally occurring protein called amyloid beta seemed to serve as a defense against microbes attacking the brain. Until now, researchers have generally believed the protein served no useful role – and, in fact, created conditions associated with Alzheimer’s.

Researchers tested their hypothesis that the protein may be useful by infecting brain cells in lab dishes, worms and mice. They found in some cases that amyloid beta protein structures quickly developed to entrap the harmful invaders. They also found that the brain cells with the active protein—first in the lab, then in worms and mice—survived infection longer than those without it.

How the protein might help

In Alzheimer’s cases, the protein structures left behind after an infection are seen as building blocks for the biological weapons that damage the brain, killing nerve cells and inflaming tissues. But the new research suggests that the protein is doing important work protecting the brain. The implication is that some minimal level of the protein is helpful, but that excessive buildup can be damaging.

In other words, instead of seeking to eliminate the protein, health care providers “might want to think about just dialing it down,” Rudolph Tanzi, a co-author of the study, told Scientific American.

The study, which includes the scientifically provocative headline “Rehabilitation of a β-amyloid bad boy,” suggests the protein plays “a dual protective/damaging role”—seeding the brain for damaging effects, but also battling microbial infections.

Many new avenues to explore in Alzheimer’s fight

The findings, Robert Moir, Tanzi’s co-author, told Science Daily, “raise the intriguing possibility that Alzheimer's pathology may arise when the brain perceives itself to be under attack from invading pathogens.”

It’s very early in the effort to find out how the proteins work in human brains, but the researchers say they have many avenues to explore. They are starting with a plan to identify and classify the microbes that exist in aged brains.

“We’re at the top of a mountain with a freshly formed layer of snow,” Moir told Scientific American. “Where you go is where you choose. There’s so much to explore.”

The study is available at the Science Translational Medicine website

If you or a loved one is showing evidence of Alzheimer’s, or if you would like to speak to someone about the disease, Providence has resources that can help. Find a provider here.


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