Qualitative Deficits in Verbal Fluency in Parkinson's Disease with Mild Cognitive Impairment: A Clinical and
Tomoya Hamada1,2, Yuichi Higashiyama1, Asami Saito1
1Department of Neurology and Stroke Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan.
Background:
Mild cognitive impairment (MCI) in Parkinson's disease (PD) is considered a risk factor for PD with dementia (PDD). Verbal fluency tasks are widely used to assess executive function in PDD. However, in cases of PD with MCI (PD-MCI), the relative diagnostic accuracy of different qualitative verbal fluency measures and their related neural mechanisms remain unknown.
Objective:
This study aimed to investigate the relative diagnostic accuracy of qualitative (clustering and switching) verbal fluency strategies and their correlates with functional imaging in PD-MCI.
Methods:
Forty-five patients with PD (26 with MCI and 19 without MCI) and 25 healthy controls underwent comprehensive neurocognitive testing and resting-state functional magnetic resonance imaging. MCI in patients with PD was diagnosed according to established clinical criteria. The diagnostic accuracy of verbal fluency measures was determined via receiver operating characteristic analysis. Changes in brain functional connectivity between groups and across clinical measures were assessed using seed-to-voxel analyses.
Results:
Patients with PD-MCI generated fewer words and switched less frequently in semantic and phonemic fluency tasks compared to other groups. Switching in semantic fluency showed high diagnostic accuracy for PD-MCI and was associated with reduced functional connectivity in the salience network.
Conclusion:
Our results indicate that reduced switching in semantic fluency tasks is a sensitive and specific marker for PD-MCI. Qualitative verbal fluency deficits and salience network dysfunction represent early clinical changes observed in PD-MCI.
Insights
Reduced switching in semantic fluency tasks is a key indicator of mild cognitive impairment in Parkinson's disease (PD-MCI). This finding highlights early cognitive changes and salience network dysfunction in PD-MCI patients.
Area of Science:
- Neuroscience
- Neurology
- Cognitive Science
Background:
- Mild cognitive impairment (MCI) in Parkinson's disease (PD) is a significant risk factor for developing Parkinson's disease dementia (PDD).
- Verbal fluency tasks are crucial for assessing executive function in PDD, but their diagnostic utility and underlying neural mechanisms in PD with MCI (PD-MCI) are not well understood.
Purpose of the Study:
- To evaluate the diagnostic accuracy of qualitative verbal fluency strategies (clustering and switching) in PD-MCI.
- To explore the functional neuroimaging correlates of these verbal fluency deficits in PD-MCI.
Main Methods:
- Recruited 45 PD patients (26 with MCI, 19 without) and 25 healthy controls for neurocognitive testing and resting-state fMRI.
- Diagnosed MCI using established clinical criteria and assessed diagnostic accuracy of verbal fluency measures via ROC analysis.
- Examined functional connectivity changes using seed-to-voxel analyses.
Main Results:
- PD-MCI patients produced fewer words and exhibited less switching in semantic and phonemic fluency tasks compared to other groups.
- Reduced switching in semantic fluency demonstrated high diagnostic accuracy for PD-MCI.
- This deficit was linked to decreased functional connectivity within the brain's salience network.
Conclusions:
- Reduced switching in semantic fluency serves as a sensitive and specific biomarker for identifying PD-MCI.
- Qualitative verbal fluency impairments and salience network dysfunction are early indicators of PD-MCI.
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