Posterior Atrophy is a Neuroimaging Marker of Mild Cognitive Impairment in Parkinson's Disease

Introduction: Although there are several studies on the neuroanatomical mechanisms underlying Parkinson's disease (PD)-associated cognitive impairment, the clinical usefulness of the findings from these investigations is limited.In this study, we aimed to identify magnetic resonance imaging (MRI) markers that can be practically utilized for diagnosing PD-associated cognitive impairment using a visual rating scale (VRS).Methods: Anatomical MRIs of cognitively normal (PD-CN), and PD with mild cognitive impairment (PD-MCI) patients were visually evaluated for six bilateral cortical regions.Then, hypothesis-driven cortical thickness analysis (CTA) was performed in the regions obtained from VRS.Results: As a consequence of VRS, a significant difference was found between the two groups with regards to right posterior atrophy (PA) scores (pFDR-corr = 0.042, Cohen's d= 1.06).Hypothesis-driven CTA confirmed the result of VRS by revealing cortical thinning at the precuneus and parieto-occipital sulcus junction (Max.T= 6.171, P= 0.0006, MNI x, y, z = 11.0,-62.2, 25.4).The area under the curve was 0.75, showing a good association between the PD-MCI and the right PA score.The cut-off for maximum accuracy was ≥ 2, based on the highest sum of sensitivity (0.68) and specificity (0.72). Conclusions:Our findings indicate that right PA atrophy may be helpful for clinicians in the diagnosis of PD-associated cognitive impairment.