Alzheimer's disease is the most common form of dementia. Disease affects memory, thinking, behavior, deprives patients of independence. Moreover, the diagnosis of Alzheimer's disease is still unreliable and complex - more than 1/3 of patients get an incorrect diagnosis.

The other day an international team of scientists announced the completion of a 10-year study, during which they went to a simpler and more reliable method of diagnosing Alzheimer's disease. The results of their work are published in The Lancet Neurology.

According to the World Health Organization, in 2010, more than 36 million people worldwide suffered from dementia. By 2030, this number should double, and by 2050 - tripled.

About 70% of cases of dementia are associated with Alzheimer's disease - a progressive brain disease in which intra-nerve cells and between them accumulate beta-amyloid. Since behavioral and cognitive impairments in Alzheimer's disease are very similar to other types of dementia, doctors are constantly confronted with difficulties in differential diagnosis, especially at an early stage.

In 2005, an international team of neurologists changed the set of diagnostic criteria for Alzheimer's disease. Before that, the only 100% reliable way to confirm the disease was an autopsy, when you can do brain tissue analysis. New criteria make it possible to detect Alzheimer's disease even in the early stages of the disease.

New diagnostic criteria for the disease.

In 2007, this group of experts presented the idea of ??using new biomarkers of Alzheimer's disease. They talked about the possibility of intravital accurate diagnosis of the disease by detecting the characteristic biological substances in the cerebrospinal fluid. When they announced new diagnostic criteria, it became a sensation.

"One group of researchers stated that 36% of their patients included in an earlier clinical study of drugs did not actually suffer from Alzheimer's," said Dr. Bruno Dubois, professor of neurology at the French biomedical institute Inserm, coordinator of the international group in 2007.

Professor Dubois, who is also the co-author of the last article, says that the prospects for their discovery are very serious. He hopes that patients who have been misdiagnosed due to incorrect diagnosis, and also participants in clinical trials, who in fact did not suffer from the disease, the drug from which they experienced.

Since 2007, much has changed, so in the light of new data, scientists again revised their proposals. According to Professor Dubois, the latter "means the end of this path".

The method proposed by scientists consists of two parts: an alleged clinical picture of three scenarios (typical, atypical and preclinical) and analysis on biomarkers. That is, the physician should be based on the clinical picture of the disease, then make a confirmation for the assay for one of the two biomarkers.

Three scenarios are:.

• A typical case (80-85% of cases): changes in the brain that lead to disruption of episodic long-term memory, including problems with memorizing lists of several words.

• Atypical case (15-20% of cases): changes in the brain that lead to problems with verbal memory and behavioral disorders.

• Preclinical conditions in which the patient does not have symptoms, but for some reason-for example, during clinical trials-he has found Alzheimer's disease markers.

Two biomarkers - only one of them is enough to confirm or deny the diagnosis of Alzheimer's disease:.

• An abnormal level of proteins in the cerebrospinal fluid - increased tau content and a lower content of beta-amyloid protein (lumbar puncture is done).

• Positron emission tomography of the brain, which shows focal diminution of cerebral metabolism.

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