Blood test predicts risk of Alzheimer's disease

Is it possible to determine Alzheimer's disease by a blood test?

Kirill Stasevich, Compulenta

Alzheimer's disease is almost untreatable, and the most that can be done with it is to slow down its development to one degree or another. It is believed, however, that anti-alzheimer's therapy would be much more effective if it were started as soon as possible, at the earliest stages of the disease. The problem is that there are still no satisfactory ways to diagnose this syndrome early.

With the exception of brain biopsies, now only two diagnostic methods allow more or less timely detection of Alzheimer's disease. The first is a brain scan in search of specific protein deposits, plaques and tangles; the second is an analysis of cerebrospinal fluid for the same alzheimeric proteins. Both are quite expensive, difficult to perform and again not too accurate in determining the early stages of the disease (this is not to mention the fact that lumbar puncture is a rather unpleasant procedure). If the signs of the disease have manifested themselves in behavior, this already indicates a very neglected disorder.

Scientists have been searching for decades for a diagnostic test for Alzheimer's disease that would be accurate, simple, cheap, non-invasive and would reliably detect the disease at the earliest stages. The attitude to simplicity and cheapness makes one think of something like a blood test - and indeed, if early diagnostic markers of the syndrome could be detected in the blood, the problem would be solved.

From time to time, there are works whose authors offer certain molecules as "witnesses" of neurodegenerative processes in the brain. Naturally, scientists did not ignore the microregulatory RNAs (which can really tell a lot about molecular and cellular processes in the body); they also tried to adapt some hormones to this case, as if they indicated the appearance of alzheimer's proteins in the brain. You can also recall a peculiar method proposed the year before last by researchers from the Spanish Institute of the Structure of Matter, who tried to detect Alzheimer's disease based on the measurement of infrared radiation absorbed or emitted by white blood cells.

But although there are quite a lot of works on this topic, their authors usually deal with a certain disease. And indeed, in order to look for a new diagnostic sign, you need to be sure that the disease has begun. However, researchers from Georgetown University (USA) approached the problem differently: they began to look for diagnostic signs of alzheimer's even before they manifested in humans. Howard J. Federoff's experiment involved several hundred elderly people over the age of 70. They were closely monitored for three years, and as a result, 53 subjects were diagnosed with mild symptoms of alzheimer's, and 18 of them had no such symptoms at the beginning of the study.

Blood samples were taken from all the subjects in advance, and it only remained to compare what biochemical features were in the blood of the patients compared to those who remained healthy. As the authors of the work in Nature Medicine (Mapstone et al., Plasma phospholipids identify antecedent memory impairment in older adults) write, they literally managed to find 10 differences – in the sense that the level of ten substances in the blood of Alzheimer's sufferers was very different from the level of the same substances in healthy people. These were phospholipids, which are part of the cell membrane of nerve cells.

It is worth noting that the researchers took into account not only those cognitive impairments caused by alzheimer's; they also assessed the blood condition of people with moderate cognitive impairments that may resemble symptoms of the syndrome, but have a different origin. But, one way or another, everything ends with the death and destruction of neurons, which is why their membrane lipids end up in the bloodstream. So with this method, it is possible to diagnose not only Alzheimer's syndrome, but also other age-related cognitive disorders.

The effectiveness of such a test, according to the researchers, is 90%, that is, in nine cases out of ten, the development of the disease can be predicted by a change in the level of specific lipids in the blood. As already mentioned, the undoubted advantage of this work is that it was possible to correlate changes in the cognitive-mental state with a blood test.

However, so far neither the authors of the work nor other scientists undertake to say how universal such "lipid divination" can be. There are fears that the researchers were just lucky, that is, they worked with people who could easily have had this very spike in lipids. Therefore, it is necessary to double-check these data more than once to make sure of the diagnostic power of the method. And such checks, of course, will follow, because, according to some estimates, by 2050 the number of patients with Alzheimer's syndrome in the world will triple...

Prepared based on the materials of the Georgetown University Medical Center:
Blood Test Identifies Those At-Risk for Cognitive Decline, Alzheimer’s Within 3 Years.

Portal "Eternal youth" http://vechnayamolodost.ru12.03.2014