Biomarker Predicts AD in People with Mild Memory Defects

A biomarker helps to identify people with mild memory deficits who will go on to develop Alzheimer's disease (AD). The biomarker may be more accurate than currently established biomarkers.

A study performed by scientists at the Technical University Munich (Germany) involved 58 people with slight memory problems, or mild cognitive impairment (MCI). People who developed AD had significantly higher levels of a protein called soluble amyloid precursor protein beta (sAPPβ) in their spinal fluid than those who did not develop Alzheimer's disease.

A sample of cerebrospinal fluid was taken from the participants at the beginning of the study through a lumbar puncture, or spinal tap. The concentrations in the cerebrospinal fluid of several proteins that are associated with Alzheimer's disease were measured.

The participants were followed for nearly three years on average. Twenty-one people had developed Alzheimer's disease, 27 still had mild cognitive impairment and 8 people had reverted back to their normal cognitive health. Two people who had developed frontotemporal dementia were not included in the analysis.

People who developed AD had significantly higher levels of a protein called soluble amyloid precursor protein beta (sAPPβ) in their spinal fluid than those who did not develop Alzheimer's disease. Those who developed Alzheimer's disease had an average of 1,200 ng/mL, compared to 932 ng/mL for those who did not develop the disease.

The investigators found that the best predictor of AD was a combination of sAPPβ, the tau protein (an established marker of brain cell damage), and the age of the individual. When these factors were combined, the results were roughly 80 % accurate in predicting whether the disease would develop.

The study was published in the June 22, 2011 online issue of Neurology, journal of the American Academy of Neurology.

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