Hope for a New Diagnostic Tool
The focus on much current Alzheimer’s research is on determining if experimental drugs that have failed in past clinical trials will be effective if they are started before people show any clinical symptoms of the disease. There are trials now underway to test this hypothesis.
How to Find Subjects Likely to Develop Alzheimer’s?
One major challenge for these trials is to identify a large enough group of asymptomatic people who can be reliably determined to have a high probability of developing Alzheimer’s within the next several years. Today, the tests used to identify such populations – PET scans that show amyloid plaques in the brain and spinal taps that reveal if someone has high levels of amyloid in the spinal fluid – are invasive, expensive, and not highly predictive. There is concern that the results of the current trials may not be conclusive, or may reach incorrect conclusions if the subject population cannot be shown to be at high risk for developing the disease.
A New Blood Test
Researchers gained new hope this week when Professor Howard Federoff of Georgetown University reported that Georgetown researchers had developed a blood test that predicted with 90% accuracy whether an individual would develop mild cognitive impairment or Alzheimer’s disease within the next three years. This report was published in a letter in the online edition of Nature Medicine.
The trial enrolled 525 subjects over the age of 70 in this trial. It took blood samples from each one and analyzed the sample with the mass spectrometer to determine precise blood chemistries. The researchers then followed all 525 individuals for the next three years, taking blood samples annually and conducting tests of cognitive function.
At the beginning of the trial, some subjects already were symptomatic for cognitive impairment. Over the course of the study, an additional 28 subjects developed cognitive impairment. Of this group, the researchers compared the blood samples of 53 individuals who had cognitive deficits against the blood samples of 53 other subjects who were normal. The control group was matched to the cognitive deficit group based on age, education and gender. The analysis showed that there were distinct differences in 10 lipids in the blood samples, which were highly predictive of Alzheimer’s disease.
Use in Future Clinical Trials
The success of this trial is very encouraging, but not definitive. First, the sample size was very small. Second, the sample was not diverse in terms of age or race, nor was it long enough to establish the predictive abilities of these biomarkers. And last, but not least, no other researcher has yet replicated these impressive results. Despite these caveats, these findings are very promising. Dr. Federoff has encouraged other scientists to conduct their own trials to see if these results can be replicated. If so, this blood test may be used to accurately select asymptomatic subjects for clinical trials on Alzheimer’s drugs. In addition, further evaluation of the lipids identified in this research may provide insights as to what triggers Alzheimer’s disease. To see more of Dr. Federoff’s insight, please view the below video via Nature News Team.