Through recent research based on human studies and laboratory experiments, scientists at the DZNE and the University Medical Center Gottingen (UMG) have identified molecules in the blood that can indicate impending dementia.

Their findings, which are presented in the scientific journal EMBO Molecular Medicine are based on human studies and laboratory experiments. Various university hospitals across Germany were also involved in the investigations.

The biomarker described by the team led by Prof. Andre Fischer is based on measuring levels of so-called microRNAs. The technique is not yet suitable for practical use; the scientists, therefore, aim to develop a simple blood test that can be applied in routine medical care to assess dementia risk. According to the study data, microRNAs could potentially also be targeted for dementia therapy.

"When symptoms of dementia manifest, the brain has already been massively damaged. Presently, diagnosis happens far too late to even have a chance for effective treatment. If dementia is detected early, the odds of positively influencing the course of the disease increase," says Andre Fischer, research group leader and spokesperson at the DZNE site in Gottingen and professor at the Department of Psychiatry and Psychotherapy at UMG.

Fischer added, "We need tests that ideally respond before the onset of dementia and reliably estimate the risk of later disease. In other words, tests that give an early warning. We are confident that our current study results pave the way for such tests."

The biomarker that Fischer and his colleagues have found is based on measuring so-called microRNAs in the blood. MicroRNAs are molecules with regulatory properties: they influence the production of proteins and thus a key process in the metabolism 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 organism. So, microRNAs have a broad impact. We wanted to find out whether there are specific microRNAs whose presence in the blood correlates with mental fitness," Fischer says.

Through extensive studies, the researchers ultimately identified three microRNAs whose levels were associated with mental performance. For this, they analyzed data from both young, cognitively normal individuals and from elderly people with mild cognitive impairment (MCI).

For the data from healthy individuals, the Gottingen scientists cooperated with Munich University Hospital. The data from MCI patients came from a DZNE study that has been running for years and involves university clinics throughout Germany. In the end, the various findings came together like pieces of a puzzle: In healthy individuals, levels of microRNAs correlated with mental fitness. The lower the blood level, the better the subjects performed in cognition tests. 

Further evidence came from patients with MCI: Of those in whom the blood marker was highly elevated, about 90 per cent developed Alzheimer's disease within two years. "We, therefore, see an increased blood level of these three microRNAs as a harbinger of dementia," Fischer says. "We estimate that in humans this biomarker indicates a development that is about two to five years in the future."