By Randy Dotinga
WEDNESDAY, Feb. 1 (HealthDay News) -- A new study suggests that a brain-clotting plaque linked to Alzheimer's disease may cause cognitive decline even in healthy people, potentially setting the stage for the development of the devastating illness later in life.
The findings don't point to any new treatment for Alzheimer's disease, which is incurable, and the detected decline in brain function is so small that affected people probably wouldn't notice anything in their daily lives.
Still, "I think they certainly are at higher risk of Alzheimer's," said study co-author Denise Park, A cognitive neuroscientist at the Center for Vital Longevity at the University of Texas at Dallas. She added that the test that turned up signs of the brain plaque could eventually help doctors figure out if someone's at risk for the disease long before they reach old age.
"Just because we don't have a treatment for Alzheimer's doesn't mean we'll never have one. What if we can develop this field enough that we can say things about your brain in your 40s and tell people, 'Here's a pill that you can take to slow [cognitive deterioration] down so it will never go to Alzheimer's?'" she said.
The plaque at issue is known as beta amyloid. It's a kind of protein that collects in the brains of people with Alzheimer's disease along with stringy "tangles" that appear in neurons. Research suggests that the plaques and neurons kill off brain cells, leading to declines in mental function.
The researchers wanted to study beta amyloid levels in people without Alzheimer's disease. They did PET scans on 137 people aged 30 to 89, and gave them several cognitive tests that measured things like memory and how fast their brains worked.
Those with higher levels of the brain gunk performed worse on cognitive tests measuring brain-processing speed, working memory and reasoning.
However, the differences in brain function may not mean much to the individuals. "In everyday life, I don't think you'd notice it," Park said
The study appears in the Feb. 1 online issue of Neurology.
What does the study suggest about the brain plaque? "One idea is that it's a first step in a cascade of events that ultimately leads to Alzheimer's disease," Park said. "Another possibility is that although the amyloid is there, maybe it won't increase or harm the individual for 20 or more years, that it doesn't progress as rapidly as many people think it does."
Dr. Brad Dickerson, an associate professor of neurology at Harvard Medical School, said the study is important because it adds to previous research that links higher levels of beta amyloid to cognitive problems.
"It will be interesting to follow these individuals over time in order to see whether these differences between people have any implications for risk for future cognitive decline," he said. "It would also be interesting to investigate other types of measures of brain structure and function in these individuals."
For more about Alzheimer's disease, try the U.S. National Library of Medicine.
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