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Signs of Alzheimer's May Show Up Years Before Symptoms

Study: Signs of Disease Seen in Brains of People Who Don't Have Alzheimer's Yet

By Denise Mann
WebMD Health News

Reviewed by Laura J. Martin, MD

Feb. 1, 2012 -- Amyloid protein plaques in the brain are a hallmark of Alzheimer's disease. Now, new research shows that this plaque actually builds up gradually and causes subtle changes in memory and mental status even in some adults who are healthy.

Alzheimer's disease is the most common type of dementia. Symptoms including serious memory loss, confusion, and mood changes that develop gradually and worsen with time.

Researchers from the Center for Vital Longevity at the University of Texas at Dallas looked at the brains of 137 healthy people aged 30 and 89 via PET scans. Participants were also tested for the APOE gene, which has been linked to increased Alzheimer's disease risk.

The amount of beta-amyloid in brains increased with advancing age. About 20% of adults aged 60 and older had high levels of plaque in their brains. Those who had the highest levels of beta-amyloid in their brains had lower scores on tests of their memory, reasoning, and processing. People with greater amounts of amyloid were also more likely to be positive for the APOE gene, the study showed.

The findings are published in the journal Neurology.

Science Moving Toward Earlier Alzheimer's Diagnosis and Treatment

Keith Black, MD, is the chairman of the department of neurosurgery and director of the Maxine Dunitz Neurosurgical Institute at Cedars-Sinai Medical Center in Los Angeles. He reviewed the findings for WebMD. Black says the new study supports the notion that changes in the brain that lead to Alzheimer's disease may begin years, or even a decade, before a person has symptoms.

"Can we diagnose it at 60 rather than at 75, and can we intervene at early stages to slow disease progression so they don't develop memory loss until age 95? This would be a therapeutic home run," he says.

We are not there yet, but there are drugs and early screening tests in the pipeline, he says.

Dean Hartley, PhD, agrees. He is an associate professor of neurosciences and a neuroscience researcher at Rush University Medical Center in Chicago. The new findings "take us closer to trying to find out when the disease begins, and then we can begin to follow the progression and start to look at drugs," he says.

There are other questions that need to be answered, says Sam Gandy, MD, PhD. He is the Mount Sinai chair in Alzheimer's disease research at Mount Sinai School of Medicine in New York City. "The finding emphasizes one area that we still understand poorly: why some people are very sensitive to amyloid poisoning and lose [mental ability] in the face of relatively low amyloid buildup."

Plenty of people can resist amyloid for decades and we would really like to understand why, he says.

If there was one thing a person could do to prevent Alzheimer's today, even in the face of amyloid build-up, it would be to exercise. "Physical exercise still seems to be the one that has the strongest effect," Gandy tells WebMD.

SOURCES: Rodrigue, K.M. Neurology. Sam Gandy, MD, PhD, Mount Sinai chair, Alzheimer's disease research, Mount Sinai School of Medicine, New York City.Dean Hartley, PhD, associate professor of neurosciences, Rush University Medical Center, Chicago.Keith Black, MD, Chairman, Department of Neurosurgery; Director of the Maxine Dunitz Neurosurgical Institute, Cedars-Sinai Medical Center, Los Angeles, Calif.

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