Increased pre-alpha functional connectivity in dementia with Lewy bodies

Background Resting-state EEG studies have shown that neurodegenerative dementias like Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) can alter cortical functional connectivity. In DLB, the presence of a pre-alpha rhythm suggests frequency-specific network dysfunctions that remain poorly understood.Objective In the present study we tested the hypothesis that electroencephalography (EEG) recordings in DLB patients may show abnormal cortical functional connectivity.Methods Resting-state EEG activity was recorded in 73 DLB, 70 AD, and 41 healthy control (HC) participants from seven European DLB Consortium Centers. We used eLORETA to calculate lagged linear connectivity (LLC) from EEG sources at delta, theta, pre-alpha, alpha, beta, gamma bands.Results Statistical analyses revealed greater fronto-occipital connectivity at the theta and pre-alpha bands in the DLB group compared to the AD and HC groups. Furthermore, the DLB and AD groups displayed reduced alpha LLC compared to the HC group.Conclusions The results suggest that in DLB patients, resting-state EEG pre-alpha activity is not a local process. Instead, it may reflect enhanced functional connectivity, possibly propagating dysfunctional thalamocortical connectivity, within long fronto-occipital tracts.