Cortical thinning associated with mild cognitive impairment in Parkinson's disease

Abstract

Objective: The aim of this study was to investigate patterns of cortical atrophy associated with mild cognitive impairment in a large sample of non-demented PD patients, and its relation with specific neuropsychological deficits. Methods: MRI and neuropsychological assessment were performed in a sample of 90 non-demented PD patients and 32 healthy controls. All underwent a neuropsychological battery including tests that assess different cognitive domains: attention and working memory, executive functions, memory, language and visuoperceptual-visuospatial functions. Patients were classified according to their cognitive status as PD patients without mild cognitive impairment (n=43) and PD patients with mild cognitive impairment (n=47). Freesurfer software was used to obtain maps of cortical thickness for group comparisons and correlation with neuropsychological performance. Results: Patients with mild cognitive impairment showed regional cortical thinning in parieto-temporal regions, increased global atrophy (global cortical thinning, total gray matter volume reduction and ventricular enlargement), as well as significant cognitive impairment in memory, executive and visuospatial and visuoperceptual domains. Correlation analyses showed that all neuropsychological tests were associated with cortical thinning in parieto-temporal regions and to a lesser extent in frontal regions. Conclusion: These results provide neuroanatomic support to the concept of MCI classified according to Movement Disorders Society criteria. The posterior pattern of atrophy in temporo-parietal regions could be a structural neuroimaging marker of cognitive impairment in non-demented PD patients. All the neuropsychological tests reflected regional brain atrophy but there were no specific patterns corresponding to impairment in distinct cognitive domains.