Default mode network links to visual hallucinations: A comparison between Parkinson's disease and multiple system...

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Default mode network (DMN) activity is crucial for understanding parkinsonisms.
• Visual hallucinations (VH) are key differentiators between Parkinson's disease (PD) and multiple system atrophy (MSA).
• Investigating DMN function in PD and MSA can elucidate the neural basis of clinical phenotypes.

Purpose of the Study:

• To compare DMN activity and connectivity in MSA versus PD.
• To explore the relationship between DMN function and the presence of VH in PD.
• To assess DMN alterations in early and severe PD stages.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to assess DMN activity and connectivity.
• Participants included MSA patients, healthy controls, early PD patients, and severe PD patients (with and without VH).
• Cortical thickness and neuropsychological tests were also conducted.

Main Results:

• MSA showed reduced DMN activity compared to controls and PD with VH.
• PD with VH had preserved DMN activity and connectivity, higher than other groups.
• DMN connectivity was reduced in early and severe PD without VH compared to controls and PD with VH.
• Cortical thickness reductions were observed in severe PD, correlating with disease duration.
• Anxiety scores were higher in patients without VH.

Conclusions:

• DMN activity and connectivity are altered in parkinsonisms, differing based on VH presence.
• MSA and PD without VH exhibit reduced DMN function, while PD with VH shows preserved function.
• Functional brain changes, not structural ones, appear to drive these DMN differences.