Weighted network measures reveal differences between dementia types: an EEG study

The diagnosis of dementia with Lewy bodies (DLB) versus Alzheimer’s disease (AD) can be difficult especially early in the disease process. However, one inexpensive and non-invasive biomarker which could help is electroencephalography (EEG). Previous studies have shown that the brain network architecture assessed by EEG is altered in AD patients compared with age-matched healthy control people (HC). However, similar studies in Lewy body diseases, i.e. DLB and Parkinson’s disease dementia (PDD) are still lacking. In this work we: 1) compared brain network connectivity patterns across conditions, AD, DLB, and PDD, in order to infer EEG network biomarkers that differentiate between these conditions, and 2) tested whether opting for weighted matrices led to more reliable results by better preserving the topology of the network. Our results indicate that dementia groups present with reduced connectivity in the EEG α band, whereas DLB shows weaker posterior-anterior patterns within the β-band and greater network segregation within the θ-band compared with AD. Weighted network measures were more consistent across global thresholding levels, and the network properties reflected reduction in connectivity strength in the dementia groups. In conclusion, β- and θ-band network measures may be suitable as biomarkers for discriminating DLB from AD, whereas the α-band network is similarly affected in DLB and PDD compared with HC. These variations may reflect the impairment of attentional networks in Parkinsonian diseases such as DLB and PDD. Keywords: biomarker, brain connectivity, Lewy body, Alzheimer’s disease, proportional thresholding, Parkinson’s disease, graph theoryThe research was funded by the NIHR Newcastle Biomedical Research Centre awarded to the Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University, and the Medical Research Council (MR/T004347/1). The study —participant recruitment and data collection— was funded by an intermediate clinical Wellcome Trust Fellowship (WT088441MA) to J.P.T