microRNA will warn about dementia
Researchers found biomarkers of dementia in the blood
Anna Yudina, "Scientific Russia"
Researchers from the German Center for Neurodegenerative Diseases and the University Medical Center of Göttingen have identified molecules in the blood that may indicate the onset of dementia, according to a press release from Researchers Find Warning Signs for Dementia in the Blood.
Their findings, which are presented in the scientific journal "Molecular Medicine EMBO" (Islam et al., A microRNA-signature that correlates with cognition and is a target against cognitive decline), are based on human studies and laboratory experiments. Various university hospitals throughout Germany were also involved in the study. The biomarker described by the team led by Professor Andre Fischer is based on measuring the levels of so-called microRNAs. The technique is not yet suitable for practical use; therefore, scientists are striving to develop a simple blood test that could be used in everyday medical care to assess the risk of dementia. According to the study, microRNAs could potentially also be targets for dementia therapy.
"When the symptoms of dementia appear, the brain is already severely damaged. Currently, the diagnosis is made too late to at least have a chance of effective treatment. If dementia is detected at an early stage, the chances of positively influencing the course of the disease increase," says Andre Fischer, head of the research group and representative of the DZNE center in Göttingen and professor of the Department of Psychiatry and Psychotherapy at UMG. – We need tests that are ideal before the onset of dementia and reliably assess the risk of later disease. In other words, tests that give an early warning. We are confident that the results of our current study open the way for such tests."
The biomarker discovered by Fischer and his colleagues is based on the measurement of so-called microRNAs in the blood. microRNAs are molecules with regulatory properties: they affect the production of proteins and, consequently, the key metabolic process of every living being. "There are many different microRNAs, and each of them can regulate entire networks of interdependent proteins and thus influence complex processes in the body. So, microRNAs have a wide influence. We wanted to find out if there are certain microRNAs whose presence in the blood correlates with mental fitness," says Fisher.
As a result of extensive studies in humans, mice, and cell cultures, the researchers eventually identified three microRNAs whose levels were associated with mental performance. To do this, they analyzed data from both young, cognitively normal people and elderly people with mild cognitive impairment (MCI). To obtain data from healthy people, Goettingen scientists collaborated with the University Hospital of Munich. Data on patients with MCI were obtained as a result of a long-term study by the German Center for Neurodegenerative Diseases with the participation of university clinics throughout Germany.
In the end, the various results came together like pieces of a puzzle: in healthy people, microRNA levels correlated with mental performance. The lower the blood level, the better the results of cognitive tests the subjects showed. In turn, in mice, this indicator increased even before the rodents began to show a decrease in mental development – regardless of whether this was due to age or because they developed symptoms similar to those of Alzheimer's dementia. Further evidence was obtained from patients with MCI: of those whose blood marker levels were greatly elevated, about 90 percent contracted Alzheimer's disease within two years. "Therefore, we consider an increased level of these three microRNAs in the blood as a harbinger of dementia," says Fisher. "According to our estimates, in humans, this biomarker indicates a development that will occur in about two to five years in the future."
In their studies on mice and cell cultures, the researchers also found that the three identified microRNAs affect inflammatory processes in the brain and "neuroplasticity," which includes the ability of neurons to establish connections with each other. This suggests that three microRNAs are more than warning signals. "In our opinion, they are not only markers, but also actively influence pathological processes. This makes them potential targets for treatment," Fischer says. – Indeed, we see that in mice, the ability to learn improves when these microRNAs are blocked by drugs. We have observed this in mice with age-related mental deficits, as well as in mice with brain damage similar to that that occurs in Alzheimer's disease."
The new marker still requires further testing; in addition, the current measurement procedure is too complicated for practical use: "In further studies, we aim to confirm this biomarker clinically. In addition, we intend to develop a simple testing procedure for screening in the places of medical care," says Fisher. – Our goal is to conduct an inexpensive test similar to the rapid test for SARS–CoV-2, with the difference that for our purposes you will need a drop of blood. Such a test can be used during routine checkups with doctors for early detection of an increased risk of dementia. Individuals with suspicious results may undergo a more thorough diagnosis."
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