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Blood Proteins Reveal Onset of Alzheimer’s

By Stephen Luntz

A selection of 11 proteins can collectively identify people with Alzheimer’s at a point where diagnosis is currently difficult, raising prospects for early intervention.

Alzheimer’s disease can only be conclusively diagnosed post mortem. “Currently, Alzheimer’s disease diagnosis is based on clinical observations and testing of cognitive capacity and memory loss,” says Prof Pablo Mascato of Newcastle University. “The only reliable and accurate biological markers so far identified for early diagnosis require measurement by either expensive procedures such as brain imaging, or invasive procedures – for example, spinal punctures.”

Mascato led a team that screened 190 proteins in blood tests for possible predictive capacity. Eleven showed promise and gave impressive results when applied to 566 people who had been tested by the international Alzheimer’s Disease Neuroimaging Initiative (ADNI).

A single test proved 85% accurate in matching ADNI’s diagnoses of either Alzheimer’s, mild cognitive impairment or normal cognition. Monitoring changes in these proteins could increase the accuracy of diagnosis above 90%, but Mascato believes that additional proteins may be found that will further improve the test’s reliability.

Early interventions, both through drugs and psychological assistance, slow the progress of Alzheimer’s disease. Diagnosis before clinical symptoms become clear could also be useful in research to identify the causes and treatments of the disease.

However, Mascato doubts the changes in protein frequency will tell us much about the causes of the disease. “At the moment we are still far from a cause. Looking at changes in blood abundance is far from telling us what is happening in the brain.

“This is more of a proof-of-concept that there are changes that can be measured. We need more specific biomarkers, and understanding of causes will probably still require investigations using brain tissue.”