Abstract
Introduction: Previous studies on electroencephalography (EEG) to discriminate between dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) have been promising. These studies did not consider the pathological overlap of the two diseases. DLB-patients with concomitant AD pathology (DLB/AD+) have a more severe disease manifestation. The EEG may also be influenced by a synergistic effect of the two pathologies. We aimed to compare EEG characteristics between DLB/AD+, “pure” DLB (DLB/AD−) and AD.Methods: We selected probable DLB patients who had an EEG and cerebrospinal fluid (CSF) available, from the Amsterdam Dementia Cohort (ADC). Concomitant AD-pathology was defined as a CSF tau/Aβ-42 ratio > 0.52. Forty-one DLB/AD+ cases were matched for age (mean 70 (range 53–85)) and sex (85% male) 1:1 to DLB/AD− and AD-patients. EEGs were assessed visually, with Fast Fourier Transform (FFT), network- and connectivity measures.Results: EEG visual severity score (range 1–5) did not differ between DLB/AD− and DLB/AD+ (2.7 in both groups) and was higher compared to AD (1.9, p < 0.01). Both DLB groups had a lower peak frequency (7.0 Hz and 6.9 Hz in DLB vs. 8.2 in AD, p < 0.05), more slow-wave activity and more prominent disruptions of connectivity and networks, compared to AD. No significant differences were found between DLB/AD+ and DLB/AD−.Discussion: EEG abnormalities are more pronounced in DLB, regardless of AD co-pathology. This emphasizes the valuable role of EEG in discriminating between DLB and AD. It suggests that EEG slowing in DLB is influenced more by the α-synucleinopathy, or the associated cholinergic deficit, than by amyloid and tau pathology.
Highlights
Previous studies on electroencephalography (EEG) to discriminate between dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) have been promising
This study shows that visual and quantitative EEG characteristics of patients with ‘‘pure’’ DLB and DLB with concomitant AD-pathology do not differ, but are both different from AD
EEG abnormalities; a lower peak frequency and more slow-wave activity; a decreased strength of alpha functional connectivity—a difference in network organization. This is the first study that takes into account concomitant AD pathology when describing EEG characteristics in DLB
Summary
Previous studies on electroencephalography (EEG) to discriminate between dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) have been promising. These studies did not consider the pathological overlap of the two diseases. Dementia with Lewy Bodies (DLB) is the most common form of dementia in the aging population after Alzheimer’s disease (AD; Zaccai et al, 2005). The most difficult discrimination is from AD, due to coinciding clinical features, as well as pathological overlap (Jellinger, 2004). The pathological substrate of DLB is aggregation of α-synuclein in Lewy bodies and neurites. Up to 50%–80% of patients with DLB have co-existing Alzheimer-pathology, i.e., amyloid plaques and neurofibrillary tangles (Jellinger and Attems, 2008; Howlett et al, 2015)
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