Scientists from St. Petersburg State University, together with doctors and employees of the research department of the 40th City Hospital, have discovered biomarkers that allow early detection of Alzheimer’s disease through a simple blood test. The results of the study were published in the journal Neurology, Neuropsychiatry, Psychosomatics.
According to the World Health Organization, Alzheimer’s disease is the most common cause of dementia in the elderly. Early diagnosis allows drug therapy to be prescribed in time, preventing deterioration and significantly improving the quality of life of patients with this diagnosis. However, Alzheimer’s disease often develops latently for a long time, which makes timely diagnosis difficult.
Informative biomarkers – the so-called labels, characteristics – allow you to find deviations from the norm and draw a conclusion about the presence of pathologies. These are a kind of indicators of biological processes in the human body, including pathological ones, which lead to the development of diseases. Such characteristics can be obtained from several sources: by molecular or histological examination, during radiography, physiological examination or psychological tests.
To date, there are several ways to detect Alzheimer’s disease, which reflect disorders of protein metabolism and neuronal degeneration, that is, the deterioration of neurons and a decrease in cognitive functions. However, for the early diagnosis of the disease, the search for the most precise markers remains of great importance, which would allow us to mark other links of neurodegenerative diseases, which are characterized by progressive cell death, leading to the degeneration of nerve tissue. .
Scientists from the University of St. Petersburg have identified biomarkers that characterize changes in patients with Alzheimer’s disease, which in the future can be used as an auxiliary diagnostic criterion to assess the severity of the disease. In addition, the scientists were able to find differences in the concentrations of biomarkers in patients with different severity of cognitive deficits. This can show various biological processes caused by the progression of the disease and, in the future, serve as a potential indicator of the presence of an active neurodegenerative process.
In medicine, three stages of Alzheimer’s disease are usually distinguished: asymptomatic pre-clinical, pre-dementia and dementia. As noted by Sergei Shcherbak, head of the Department of Postgraduate Medical Education at St. Petersburg University, it is in the first asymptomatic stage that the use of biomarkers allows detecting the causes of deviations from the norm in patients without symptoms or with their mild manifestations.
Nowadays, biomarkers obtained from cerebrospinal fluid are used to diagnose Alzheimer’s disease, but the accuracy of the results depends to a large extent on the research centers and the equipment used. In addition, the process of taking a sample of cerebrospinal fluid – lumbar puncture – is an invasive and demanding procedure, especially for older people who are more susceptible to Alzheimer’s disease.
Doctors at the University of St. Petersburg suggest studying a blood test to determine biomarkers: the relationship between their concentration in blood plasma and cerebrospinal fluid has already been discovered and is also combined with the results of neuropsychological texts. This greatly simplifies the diagnosis, because a blood test is a much easier way to look for Alzheimer’s disease biomarkers compared to a lumbar puncture.
According to the results of the studies, doctors identified the most promising biomarker in blood plasma – sICAM-1. It is a soluble cell adhesion molecule and an indicator of endothelial dysfunction, which is also seen in older adults with vascular cognitive impairment. In addition, this marker reflects the disruption of the endothelium in patients not only with vascular cognitive impairment, but also with an active neurodegenerative process in the dementia phase.
Scientists have found other biomarkers that also hold promise for detecting specific abnormalities. For example, IL-IRA scores can be considered as a diagnostic marker in the early stages of the disease. In turn, the G-CSF biomarker may be considered in the future as a potential diagnostic biomarker for Alzheimer’s disease in the dementia phase.
“Many stereotypes believe that the brain is limited by blood flow through the blood-brain barrier, a system that protects the brain from the action of foreign and toxic substances and that also participates in the transport of substances from the blood to the brain. But in neurodegenerative diseases, inflammatory processes in the brain they can not only worsen and intensify neurodegeneration, but also protect brain cells from harmful effects and perform a neuroprotective function,” said Sergei Shcherbak, head of the Department of Postgraduate Medical Education of St. Petersburg State University.
However, if this happens regularly, the efficiency of splitting amyloid plaques in the body decreases; it is their formation that is considered the main cause of neuronal death in Alzheimer’s disease.
While working on the basis of city hospital number 40, scientists examined 52 patients with Alzheimer’s disease: 39 women aged 64 to 80 years and 13 men aged 58 to 79 years. The scientists performed a positron emission tomography scan of the brain using deoxyglucose. The results of the study confirmed alterations in the functioning of brain structures, which is consistent with the results of blood tests.
In addition, all participants underwent neuropsychological studies using seven tests to detect cognitive impairment: the scientists evaluated visuospatial and control functions, attention, speed of thought processes and hand-eye coordination. All patients had varying degrees of cognitive impairment, which, with the development of Alzheimer’s disease, leads to a gradual deterioration of cognitive functions and motor impairment.
To date, the diagnosis of Alzheimer’s disease by the results of a blood test is practically not carried out. Blood serum biomarkers isolated by a group of doctors have undergone numerous tests and proved their effectiveness, which in the future may become the basis for a fairly simple diagnosis of Alzheimer’s disease in the early stages. However, as the scientists point out, additional studies are needed for its application in real clinical practice.
September 21 is International Alzheimer’s Disease Awareness Day, established in 1994 by organizations that research the disease.
The study of biomarkers for the detection of Alzheimer’s disease was carried out by scientists of St. Petersburg State University together with specialists of the Military Medical Academy named after SM Kirov, Northwestern State University named after II Mechnikov based at the city hospital. No. 40 in the Kurortny district of St. Petersburg.
Press service of St. Petersburg University