Decreased delta-band event-related power in dementia with Lewy bodies with a mutation in the glucocerebrosidase gene

Objective: To compare event-related oscillations in patients with dementia with Lewy bodies (DLB) who are carriers and non-carriers of glucocerebrosidase (GBA) mutations. Methods: EEG was recorded during a visual oddball task in eight Ashkenazi Jewish DLB patients with the N370S mutation in the GBA gene (GBA-DLB) and eleven DLB non-carriers. The time–frequency power and inter-trial phase clustering were calculated from the Morlet wavelet convolution for the midline electrodes. Results: Task performance and cognitive assessments were comparable between groups. While the within-non-GBA-DLB group analysis revealed delta-band power synchronization relative to the baseline (p = 0.01, Cohen's d = 1.0), the within-GBA-DLB-group analysis detected no event-related changes in power. Both groups showed an increase relative to the baseline in the delta and theta bands inter-trial phase clustering (all p < 0.03, d > 1.3). The between-group analysis revealed that event-related power – but not clustering – was lower in GBA-DLB compared to non-carriers in the delta band at Fz and Cz (p = 0.04, d = -0.9). Conclusions: GBA-DLB patients showed decreased delta-band power compared to non-carriers despite the similar cognitive performance, whereas inter-trial phase clustering was comparable in both groups. Significance: Preserved inter-trial phase clustering possibly compensates for the impaired power by eliciting the appropriate functional configuration needed for stimulus processing and task performance.