Alzheimer's Disease: Signs May Appear Decade Before Symptoms
Brain shrinking precedes memory loss by nearly 10 years, researchers say.
April 13, 2011— -- The brain areas affected by Alzheimer's disease start shrinking up to a decade before symptoms like memory loss appear, according to new brain imaging research. The discovery, which adds to growing evidence that Alzheimer's is a slowly emerging disease, could help scientists identify people at risk before the damage is done.
The research team, led by Dr. Bradford Dickerson, associate professor of neurology at Harvard Medical School and director of the Frontotemporal Dementia Unit at Massachusetts General Hospital in Boston, assessed the size of the hippocampus -- the brain's memory center -- and other brain regions affected by Alzheimer's disease. They used magnetic resonance imaging in 65 people who were cognitively normal. Among those with the smallest Alzheimer's-related brain area measurements, 55 percent were later diagnosed with the disease.
"It tells us that areas of the brain that are important for memory and other aspects of thinking are beginning to shrink in people who don't yet have symptoms," said Dickerson, lead author of the study published today in the journal Neurology. "We at least have the potential to detect changes a number of years in advance, and hopefully we could do something about it."
Alzheimer's disease, the most common cause of dementia among older adults, is estimated to affect 5 million Americans and is the fifth leading cause of death in the United States, according to the U.S. Centers for Disease Control and Prevention.
Dickerson compared detecting Alzheimer's-related brain shrinkage to measuring cholesterol levels in someone at risk for heart disease.
"We need to be developing a cholesterol test for Alzheimer's disease, in a sense," he said. "We need to have markers that we can identify in people that are still normal to boost that chance of preventing or slowing the disease."
But a dearth of effective treatments means early detection won't yet save lives.
"This imaging finding will not translate into new treatments. However, it does increase the rationale for utilizing preventive therapies," said Dr. Steven DeKosky, professor of neurology and dean of the University of Virginia School of Medicine.