Cortical Thickness Alterations in Parkinson's Disease with Mild Cognitive Impairment

Objective: This study investigated cortical thickness differences and their relationships with cognitive functions in Parkinson's disease (PD) with mild cognitive impairment (MCI) and cognitively normal (CN). Materials and Methods: Twenty-two patients with PD-MCI, 23 with PD-CN, and 23 healthy controls with structural brain magnetic resonance imaging scans and complete neuropsychological tests were enrolled in this study. Cortical thickness analysis was performed using the Statistical Parametric Mapping 12 software package. Correlations with cognitive functions were examined. Results: Cortical thickness was significantly lower in the PD-CN and PD-MCI patient groups than in healthy controls in the left precuneus and isthmus-cingulate cortex, right pars orbitalis, insula, and lateral orbitofrontal cortex. In addition, the PD-MCI group also exhibited cortical thinning in the left superior temporal gyrus, transverse temporal cortex, supramarginal gyrus, and bilateral posterior cingulate cortex compared with healthy controls. Correlation analyses among cortical thickness and cognitive scores of PD also revealed moderate associations between memory and the posterior cingulate cortex; language and the precuneus; and executive functions and the insula and isthmus-posterior cingulate cortices. Conclusion: MCI in PD may be related to cortical alterations in the posterior cingulate cortex and the left temporoparietal cortex, which has been associated with subtle cognitive deficits in PD.