Functional Disconnectivity during Inter-Task Resting State in Dementia with Lewy Bodies

Abstract

Aims: Limited research has been done on the functional connectivity in visuoperceptual regions in dementia with Lewy bodies (DLB) patients. This study aimed to investigate the functional connectivity differences between a task condition and an inter-task resting state condition within a visuoperceptual paradigm, in DLB patients compared with Alzheimer disease (AD) patients and healthy elderly control subjects. Methods: Twenty-six DLB, 29 AD, and 22 healthy subjects underwent a detailed clinical and neuropsychological examination along with a functional MRI during the different conditions of a visuoperceptual paradigm. Functional images were analyzed using group-level spatial independent component analysis and seed-based connectivity analyses. Results: While the DLB patients scored well and did not differ from the control and AD groups in terms of functional activity and connectivity during the task conditions, they showed decreased functional connectivity in visuoperceptual regions during the resting state condition, along with a temporal impairment of the default-mode network activity. Functional connectivity disturbances were also found within two attentional-executive networks and between these networks and visuoperceptual regions. Conclusion: We found a specific functional profile in the switching between task and resting state conditions in DLB patients. This result could help better characterize functional impairments in DLB and their contribution to several core symptoms of this pathology such as visual hallucinations and cognitive fluctuations.

Altered structural connectivity networks in dementia with lewy bodies

“…4 ), with key regions being lost and assigned to other brain networks, especially inferior frontal, posterior cingulate and occipital cortex. These findings are in accordance with several fMRI studies showing disrupted DMN network in DLB (Chabran et al 2018 ; Schumacher et al 2019 ). Similarly, Sala et al applied seed-based interregional correlation analyses using fluorodeoxyglucose PET, showing that DMN and DAN were particularly vulnerable large-scale networks in DLB (Sala et al 2019 ).…”

Evaluating the Sustained Attention Response Task to Quantify Cognitive Fluctuations in Dementia With Lewy Bodies

“…38 The activation of the DMN has also been positively correlated with errors made in a CRT. 39 However, the impact of the DMN using standard functional magnetic resonance imaging (fMRI) methods is debated [40][41][42][43][44][45] while a recent article by Schumacher and colleagues 46 further implicated a role for the DMN with potential electroencephalogram (EEG) markers of fluctuations.…”

(Dis‐)Connected Dots in Dementia with Lewy Bodies—A Systematic Review of Connectivity Studies

“…network (FPN) 37,38 as well as between the FPN and default mode network (DMN) 39 and dorsal attention network (DAN 40 ). In contrast, Chabran and colleagues showed an increase in connectivity between a left temporal FPN ROI and a left visuoperceptual ROI, whereas the correlation between visuoperceptual ROIs was decreased.…”

“…76,77 Despite the described associations between connectivity disruptions and DLB core clinical features, these associations did not consistently materialize in all studies. 27,29,35,39,59 This may be attributable to the diverse range of symptoms in patients with DLB, since the presence of two core clinical features or the combination of one core clinical feature and one indicative biomarker…”

“…36 Apart from these more explorative approaches, most fMRI-based connectivity articles focused on specific resting-state networks. Several studies found a reduction of functional connectivity within the frontoparietal network (FPN) 37,38 as well as between the FPN and default mode network (DMN) 39 and dorsal attention network (DAN 40 ). In contrast, Chabran and colleagues showed an increase in connectivity between a left temporal FPN ROI and a left visuoperceptual ROI, whereas the correlation between visuoperceptual ROIs was decreased.…”