Functional and structural network changes related with cognition in semantic dementia longitudinally

Area of Science:

• Neuroimaging
• Cognitive Neuroscience
• Neurology

Background:

• Longitudinal changes in brain networks in semantic dementia (SD) and their cognitive impact are not well understood.
• Understanding these changes is crucial for tracking disease progression and developing targeted therapies.

Purpose of the Study:

• To investigate longitudinal changes in structural and functional brain networks in SD.
• To explore the relationship between network alterations and semantic cognitive decline.
• To identify key brain regions involved in semantic processing.

Main Methods:

• Employed graph theory to analyze neuroimaging data (T1, DTI, fMRI) from 31 SD patients and 20 controls.
• Assessed cognitive performance in general and modality-specific semantic knowledge.
• Utilized partial correlation to link network changes with semantic performance decline.

Main Results:

• SD patients showed progressive semantic impairment affecting general and modality-specific knowledge.
• Functional brain networks demonstrated decreased global and local efficiency, while structural networks remained largely preserved over two years.
• Disease progression led to structural and functional alterations in temporal and frontal lobes.
• Left inferior temporal gyrus (ITG.L) alterations correlated with general semantic processing deficits.
• Right superior temporal gyrus and supplementary motor area linked to color and motion semantic attributes.

Conclusions:

• Semantic dementia involves disrupted longitudinal structural and functional network patterns.
• Identified ITG.L as a potential hub region for the semantic network.
• Highlighted distributed, modality-specific regions involved in semantic processing.
• Findings support the hub-and-spoke semantic theory and suggest therapeutic targets.