2023-09-07 20:42:14
Many scientists are working to develop tests that can reliably diagnose Alzheimer’s disease and predict its course in order to make it possible to screen people who will suffer from this disease before they show symptoms.
Researchers from Emory University in Atlanta presented this Wednesday, September 6, in Science Translational Medicinethe test they designed that increases the reliability of the prediction.
Doctors usually diagnose Alzheimer’s disease in people who begin to show symptoms using regarding 30 questions that measure their cognitive abilities. The reliability of the diagnosis obtained in this way is regarding 80%, points out Dr. Judes Poirier, who is director of the Molecular Neurobiology Unit at the Douglas Research Center.
To increase the accuracy of the diagnosis, some neurologists will take cerebrospinal fluid by lumbar puncture – in which the brain and spinal cord bathe – in order to measure the concentration of three molecules which are abnormally abundant in the brains of people with AD. Alzheimer’s. “The detection of these three disease markers, beta-amyloid 42, total tau protein and phospho-tau 181, allows us to detect people who will develop Alzheimer’s in the relatively near future with a reliability of 90%,” says Dr. Poirier, a professor in the Department of Psychiatry at McGill University.
The test presented by the Emory University researchers involves taking cerebrospinal fluid in which they are looking for 48 other molecules that appear to be abnormal in people with Alzheimer’s.
Their test, which they tested in individuals at different stages of the disease, some of whom were still asymptomatic, allows a diagnosis with an accuracy of 94%.
“It’s a gain [de 4 %] and the choice of molecules is completely justified on the basis of our knowledge of the emergence of the disease. But this test requires a very sophisticated technology which requires a large quantity of sample, which is complex and very expensive, and which, therefore, does not really lend itself to the clinic”, comments Dr Poirier who is a little disappointed. by the performance of the test, which increases the precision of the predictability of the disease by only 4%.
The Emory University team is one of a dozen different groups around the world working to develop a method that would allow early diagnosis to be made with high reliability. It is therefore a very dynamic subject of research, since early detection would make it possible to delay the onset of symptoms through early treatment.
The silent phase of the disease, which precedes symptoms, is estimated to last between 20 and 30 years, while the symptomatic phase between 8 and 11 years. “That means we are two-thirds of the way there when the symptoms appear. It is clear that any important biological change does not occur only when the symptoms appear. The two decades preceding the expression of the disease are therefore the most strategic,” points out Dr. Poirier.
“One day, we will no longer wait for symptoms to appear to treat someone. People who are on an Alzheimer’s trajectory in their 40s and 50s will be identified, and treatment will begin right away to delay the disease long enough for people to die of old age or other conditions than Alzheimer’s disease. ‘Alzheimer’, continues this great specialist in Alzheimer’s.
Dr. Poirier’s team is also working on designing a more reliable diagnostic test. She looked at 291 molecules that seemed to be involved in Alzheimer’s. “Our test increases accuracy over using all three markers, but not dramatically. But we discovered that a dozen of these molecules had a much more elaborate biological role than we had imagined. Each of these molecules is the subject of research in my laboratory, because determining their role, their precise contribution to the disease will help us better understand the causes of Alzheimer’s,” says the researcher.
“One of these molecules – which is abnormally expressed (ie too abundant) 10 to 15 years before the onset of symptoms – is associated with insulin. She comes to get the insulin once it has finished its action and she takes it to have it degraded,” says Dr. Poirier.
The latter was not surprised to find an abnormality in the level of insulin, because diabetes is a major risk factor for Alzheimer’s disease. “Uncontrolled diabetes doubles or even triples the risk of one day suffering from Alzheimer’s,” he warns.
“When you meet the children of people [souffrant ou ayant souffert d’Alzheimer] and who are therefore at risk because of their family history, we check whether they have diabetes, hypertension and high cholesterol, which are three important risk factors following those of age [avancé] and sex [les femmes sont deux à trois fois plus à risque que les hommes]. As we have multiple molecules to control hypertension, cholesterol and diabetes, we can thus reduce their risk of developing Alzheimer’s by managing these three factors”, he indicates.
Obviously, we are finally making progress in the prevention of this disease which abounds.
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