Semantic fluency deficits and associated brain activity in Parkinson's disease with mild cognitive impairment
Jihyun Yang1, Katie L McMahon2, David A Copland1,3
1UQ Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Herston, Queensland, Australia.
Abstract:
People living with Parkinson's disease (PD) with poor verbal fluency have an increased risk of developing dementia. This study examines the neural mechanisms underpinning semantic fluency deficits in patients with PD with mild cognitive impairment (PD-MCI) compared to those without MCI (PD-NC) and control participants without PD (non-PD). Thirty-seven (37) participants with PD completed a cognitive assessment battery to identify MCI (13 PD-MCI). Twenty sex- and age-matched non-PD patients also participated. Participants were scanned (3T Siemens PRISMA) while performing semantic fluency, semantic switching, and automatic speech tasks. The number of responses and fMRI data for semantic generation and semantic switching were analyzed. Participants also completed a series of verbal fluency tests outside the scanner, including letter fluency. Participants with PD-MCI performed significantly worse than PD-NC and non-PD participants during semantic fluency and semantic switching tasks. PD-MCI patients showed greater activity in the right angular gyrus than PD-NC and non-PD patients during semantic switching. Increased right angular activity correlated with worse verbal fluency performance outside the scanner. Our study showed that the PD-MCI group performed worse on semantic fluency than either the PD-NC or non-PD groups. Increased right angular gyrus activity in participants with PD-MCI during semantic switching suggests early compensatory mechanisms, predicting the risk of future dementia in PD.
Insights
Parkinson's disease (PD) patients with mild cognitive impairment (PD-MCI) show worse verbal fluency. Increased right angular gyrus activity in PD-MCI during semantic switching may indicate early compensatory mechanisms for dementia risk.
Area of Science:
- Neuroscience
- Cognitive Neurology
- Neurology
Background:
- Parkinson's disease (PD) is associated with an increased risk of dementia, particularly in individuals with impaired verbal fluency.
- Semantic fluency deficits are a key indicator of cognitive decline in PD.
- Understanding the neural basis of these deficits is crucial for early detection and intervention.
Purpose of the Study:
- To investigate the neural mechanisms of semantic fluency deficits in Parkinson's disease with mild cognitive impairment (PD-MCI).
- To compare brain activity during semantic tasks between PD-MCI, Parkinson's disease without mild cognitive impairment (PD-NC), and non-Parkinson's disease (non-PD) control groups.
- To explore the relationship between neural activity, cognitive performance, and dementia risk in PD.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to scan 37 PD patients (13 PD-MCI) and 20 non-PD controls during semantic fluency, switching, and automatic speech tasks.
- Behavioral verbal fluency tests, including letter fluency, were administered outside the scanner.
- fMRI data and behavioral performance were analyzed to identify group differences and correlations.
Main Results:
- Participants with PD-MCI demonstrated significantly poorer performance on semantic fluency and switching tasks compared to PD-NC and non-PD groups.
- PD-MCI patients exhibited heightened activity in the right angular gyrus during semantic switching compared to the other groups.
- Increased right angular gyrus activity was correlated with diminished verbal fluency performance.
Conclusions:
- The PD-MCI group's impaired semantic fluency performance highlights a significant cognitive challenge.
- Elevated right angular gyrus activation in PD-MCI during semantic switching may represent an early compensatory mechanism.
- These findings suggest that right angular gyrus hyperactivity could serve as a potential biomarker for predicting future dementia risk in Parkinson's disease.
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