Study identifies possible earliest stage of Alzheimer's disease

Amyloid plaque, clusters of a sticky protein, found in the brain point to mental decline years before first symptoms appear in Alzheimer's disease.

By Amy Wallace

June 13 (UPI) -- A study by the University of Southern California found elevated levels of amyloid plaque in the brain are the first signs in the earliest stage of Alzheimer's.

Researchers at the Keck School of Medicine at USC analyzed 10 years of data and found that elevated levels of amyloid plaque, clusters of a sticky protein, found in normal cognitive functioning older adults may be the earliest stage of Alzheimer's disease.


The study, published June 13 in JAMA, focused on amyloid levels in 445 cognitively normal individuals in the United States and Canada through cerebrospinal fluid taps or positron emission topography, or PET, scans. Approximately 242 participants had normal amyloid levels and 202 had elevated levels.

Researchers found the elevated amyloid group was older and less educated, in addition to carrying at least one extra copy of the ApoE4 gene -- increasing the odds for developing Alzheimer's disease.

"To have the greatest impact on the disease, we need to intervene against amyloid, the basic molecular cause, as early as possible," Paul Aisen, director of the USC Alzheimer's Therapeutic Research Institute [ATRI] at the Keck School of Medicine, said in a press release. "This study is a significant step toward the idea that elevated amyloid levels are an early stage of Alzheimer's, an appropriate stage for anti-amyloid therapy."


Amyloid plaque in the brain is similar to cholesterol in the blood, as both are warning signs of impending diagnosis of Alzheimer's or a heart attack.

Researchers found that the incubation period with elevated amyloid plaques, also known as the asymptomatic stage, may last longer than the dementia stage of the disease.

According to Alsen, one in three adults over age 65 have elevated amyloid plaques in the brain leading to symptomatic Alzheimer's disease in 10 years.

Researchers suggest that if Alzheimer's prevalence estimates included the preclinical stage before symptoms appear than the number of people affected would more than double from the current 5.4 million Americans.

"We need more studies looking at people before they have Alzheimer's symptoms," Aisen said. "The reason many promising drug treatments have failed to date is because they intervened at the end-stage of the disease when it's too late. The time to intervene is when the brain is still functioning well -- when people are asymptomatic."

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