Neurodegeneration
Brain activity during attention tasks in LBD and Alzheimer's
Open access · cc by · source: Europe PMC
Alzheimer's disease and Lewy body dementia show distinct patterns of default mode network deactivation during attentional tasks despite similar behavioral deficits.
Key findings
Both dementia groups showed slowed reaction times and worse accuracy compared to controls, but did not differ from each other behaviorally. Neuroimaging showed that while both dementia groups activated normal frontoparietal networks, only the Lewy body dementia group showed healthy-like deactivation of the default mode network during the executive control task, whereas the Alzheimer's disease group failed to deactivate this network.
Methodology
The researchers scanned 23 healthy older controls, 23 participants with Alzheimer's disease, and 32 participants with Lewy body dementia while they completed a modified Attention Network Test. This test evaluated how participants responded to visual cues and resolved conflict when identifying the direction of arrow targets under different levels of difficulty.
Limitations
Because the study utilized visual stimuli, the findings might be confounded by visual-perceptual deficits common in Lewy body dementia. The potential influence of concurrent medications, such as cholinesterase inhibitors or dopaminergic treatments, could not be completely ruled out. Additionally, the analysis was restricted to regional cortical activity and did not map subcortical pathways or measure underlying amyloid pathology directly.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
During executive attention tasks, healthy brain function requires the deactivation of the default mode network (DMN), a BOLD response pattern that is selectively lost in Alzheimer's disease patients but preserved in Lewy body dementia patients despite similar behavioral performance.
Evidence for the claim as stated.
The Attention Network Test can be combined with electrophysiological or functional neuroimaging methods to map the distinct neural correlates and brain regions active during target selection and conflict resolution.
Evidence for the claim as stated.
Neurodegenerative diseases such as Alzheimer's disease and Lewy body dementia impair general performance on the ANT, causing slower reaction times and reduced accuracy compared to healthy controls.
Evidence for the claim as stated.
Alzheimer's disease and Lewy body dementia patients display identical behavioral deficits on the ANT but show distinct patterns of functional brain activity, specifically regarding default mode network deactivation.
Evidence for the claim as stated.
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