Dementia Screening May be Possible with Blood Test

Could predict risk years before symptoms appear

20 January 2011

A blood test that checks for levels of the Beta-amyloid protein could predict dementia risk.

The most common form of dementia is Alzheimer's Disease, and currently, it can only be definitively diagnosed in an autopsy, by examining the brain. Beta-amyloid is a protein that shows up the brains of Alzheimer's victims. It's also present in spinal fluid and, in very small quantities, in the blood.

In a new report, researchers used nine years of data gathered on individuals who showed no sign of dementia when they started the study. Blood samples taken at the beginning of the study were compared with dementia scores at the end of the trial.

Professor Kristine Yaffe of the University of California, San Francisco, says the less beta-amyloid in a person’s blood, the higher their risk of dementia "because the idea is that it's clumping up or building in the brain. Therefore it's somehow lower when you measure it outside the brain."

Yaffe and her colleagues also found that people with low levels of beta-amyloid - what she calls an "at-risk signature" - tended to avoid dementia if they had more education or were mentally active.

There are no effective medical treatments to prevent Alzheimer's Disease. But she says this finding suggests that there might be a good reason to learn if you are at higher risk of dementia.