Salience Network and Depressive Severities in Parkinson's Disease with Mild Cognitive Impairment: A Structural Covariance Network Analysis.

Ya-Ting Chang,Chi-Wei Huang,Wen-Neng Chang,Jun-Jun Lee,Ming-Kung Wu,Cheng-Hsien Lu,Chiung-Chih Chang,Shih-Wei Hsu,Chia-Yi Lien

doi:10.3389/fnagi.2017.00417

Abstract

Purpose: In Parkinson’s disease with mild cognitive impairment (PD-MCI), we investigated the clinical significance of salience network (SN) in depression and cognitive performance.Methods: Seventy seven PD-MCI patients that fulfilled multi-domain and non-amnestic subtype were included. Gray matter structural covariance networks were constructed by 3D T1-magnetic resonance imaging and seed based analysis. The patients were divided into two groups by psychiatric interviews and screening of Geriatric Depression Scale (GDS): PD-MCI with depression (PD-MCI-D) or without depression (PD-MCI-ND). The seed or peak cluster volume, or the significant differences in the regression slopes in each seed-peak cluster correlation, were used to evaluate the significance with the neurobehavioral scores.Results: This study is the first to demonstrate that the PD-MCI-ND group presented a larger number of voxels of structural covariance in SN than the PD-MCI-D group. The right fronto-insular seed volumes and the peak cluster of left lingual gyrus showed significant inverse correlation with the Geriatric Depression Scale (GDS; r = -0.231, P = 0.046).Conclusions: This study is the first to validate the clinical significance of the SN in PD-MCI-D. The right insular seed value and the SN correlated with the severity of depression in PD-MCI.

Highlights

Parkinson’s disease with mild cognitive impairment (PD-MCI) is conceptualized as a transitional state between normal cognition and dementia, it is a major predictor for the conversion of dementia (Domellof et al, 2015)
The PD-MCI was lower than the normal control (NC) in Mini-Mental State Examination (MMSE) scores (p = 0.003), scores in digital forward and backward, lower semantic verbal fluency scores and higher Geriatric Depression Scale (GDS) than NC (P < 0.05)
The right superior occipital and frontal gyri and the left supramarginal gyrus were highlighted for the difference in regional brain volume observed in the PD-MCI-D and PD-MCI-ND groups when compared with the NC group (p < 0.001)

Summary

Introduction

Parkinson’s disease with mild cognitive impairment (PD-MCI) is conceptualized as a transitional state between normal cognition and dementia, it is a major predictor for the conversion of dementia (Domellof et al, 2015). For PD-MCI, the natural history of PD-MCI-D does not parallel that of motor symptoms, suggesting the distinctive pathophysiological mechanism (Brown and Jahanshahi, 1995). In this context, it is of clinical relevance to explore the neural basis of PD-MCI-D. In Parkinson’s disease, the salience network (SN) has been implicated in emotional processing and depression (Remy et al, 2005). The reduced Blood oxygenation level dependent (BOLD) response and reduced gray matter (GM) volume within the SN in Parkinson’s disease have been reported to mediate the emotional valence (Cardoso et al, 2009; Kostic et al, 2010). Despite the solid evidence of SN in PD with depression (Beyer et al, 2007; Kostic et al, 2010; Song et al, 2011), whether the changes in the SN mediate the depression state in PD-MCI is not fully investigated

Methods

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Discussion

Conclusion