Quantitative EEG in Alzheimer´s diagnostics

Alzheimer`s disease (AD) is a progressive fatal brain disorder that entails severe social and economic consequences. At this time, there is no cure for AD and its cause and progression are not completely understood. A definite diagnosis can only be made after death. Clinical studies suggest the electroencephalogram (EEG) as diagnostic tool. The aim of the project "Quantitative EEG in Alzheimer`s Diagnostics" is to evaluate whether the changes that happen in the EEG of AD patients can provide valuable information for the diagnosis. The research questions aim at answering whether EEG can be used for 1) differentiating between the disease stages, 2) diagnosing AD severity, 3) prognosing the rate of cognitive decline and 4) providing supplementary information to other AD-related diagnostic tools. For this purpose, data from a Danish database and the Austrian Prospective Dementia Registry (PRODEM) , both complying with the highest ethics standards, will be used in this study that will take place at the Technical University of Denmark (DTU). Glostrup Hospital (GH) and the Austrian Alzheimer Society (AAS) will act as research partners. Careful data processing will provide the basis for measuring the following changes in the EEG of AD patients that have been described in scientific literature: EEG signals become slower, they come less synchronous and less complex. A variety of measures for these three changes will be correlated with the physical and cognitive degenerations in AD and will provide insights into the course of the disease.. EEG offers several benefits to other clinical screening methods: it can be used on the skin surface, most hospitals are equipped with EEG recorders and recording an EEG is involved with low cost; for these reasons, it offers a promising tool for screening a large population for the risk of AD. As diagnostic supplement, it could provide more reliable medical assessments and, thus, enable adequate treatment delaying the cognitive decline. It could facilitate consultation-seeking, planning and decision-making for patients, caregivers and clinicians. There are very few studies with a comparable sample size and only a small number with repeated measurements on the same persons. The fact that the data are coming from two different countries ensures that there will be no national bias corrupting the analysis. The hereby initiated Austrian-Danish cooperation will yield an opportunity for expanding the AD- related research and, thus, improving AD diagnostics.

In his project "Quantitative EEG in Alzheimer's diagnostics" - sponsored by an Erwin Schrödinger Grant of the Austrian Science Fund (FWF) - Dr. Markus Waser has evaluated brain screenings such as electro-encephalography (EEG) or magnetic resonance imaging (MRI) as potential markers of the disease severity of Alzheimer's dementia. The project was conducted in an international and interdisciplinary environment at the Technical University of Denmark (DTU) in collaboration with the Danish Rigshospitalet and the Austrian Alzheimer Society. Thereby, both the highest technical and medical expertise was guaranteed. The Danish and Austrian hospitals provided anonymized clinical data from patients with varying disease severity. The project was divided into four sub-studies: The first part was concerned with the method and software development for the efficient processing of clinical data. Particularly the removal of spurious noise in EEG data was hereby investigated. Part two evaluated the potential of combined EEG-MRI markers to determine the present severity of cognitive impairment in Alzheimer's patients. Subjects with very mild impairment were hereby distinguished from mild-to-moderate impaired subjects with 85% accuracy. The third part considered EEG data from healthy Danes with varying cognitive abilities, since a declined cognition might be an early warning symptom for later neurological disorders. Here, the EEG was recorded during sleep since memory and cognition are closely linked to the different sleep stages. Participants with cognitive decline from 18 to ca. 58 years of age were hereby identified with 72% accuracy. The fourth and last part of the project was the clinically most- relevant one; it was concerned with the prediction of the disease progression of Alzheimer's dementia from EEG and MRI markers combined with socio-demographic and other clinically relevant information such as life-style (e.g. smoking, alcohol) or other diseases (e.g. diabetes). To this aim, longitudinal screenings from Alzheimer's patients with one year in- between were used. At this point in time, the analyses have not been finished; the results are expected to be published within this year (2018). To conclude, this project has strengthened the Austrian-Danish collaboration in this field and has created new networks with the potential to further increase the efforts in future Alzheimer's research.