Precuneus Dysfunction in Parkinson's Disease With Mild Cognitive Impairment

Abstract

Background: Mild cognitive impairment (MCI) frequently occurs in Parkinson's disease (PD). Neurovascular changes interact with neurodegenerative processes in PD. However, the deficits of cerebral blood flow (CBF) perfusion and the associated functional connectivity (FC) in PD patients with MCI (PD-MCI) remain unclear. Purpose: This study aimed to explore the specific neurovascular perfusion alterations in PD-MCI compared to PD with normal cognition (PD-NC) and healthy controls (HCs), and to further examine the resultant whole brain FC changes in the abnormal perfusion regions. Methods: Relative CBF (rCBF) was calculated using arterial spin labeling (ASL) in 54 patients with PD (27 patients with PD-NC and 27 patients with PD-MCI) and 25 HCs matched for age and gender ratio, who also underwent the structural MRI, resting-state functional MRI (rs-fMRI) and neuropsychological examinations. The gray matter (GM) changes in PD patients were analyzed using voxel-based morphometry (VBM). The alterations in rCBF perfusion and FC among groups were then analyzed respectively. Additionally, correlations between these alterations and neuropsychological performances were further examined. Results: Compared to HC, left caudate atrophy was detected in patients with PD. In comparison to both PD-NC and HC, patients with PD-MCI specifically exhibited hypoperfusion in the parietal memory network (PMN) in the precuneus (PCu) and decreased PCu-FC in the right striatum. Moreover, PCu perfusion and PCu-FC strengths in the right striatum were positively associated with memory performance in PD-MCI. Conclusions: These findings suggest that the posterior PMN dysfunction underlies memory deficits in PD-MCI.

Keywords: Parkinson’s disease with mild cognitive impairment; arterial spin labeling (ASL); functional connectivity (FC); parietal memory network; precuneus.

Figure 1

Decreased rCBF values in the Lt.PCu specific to PD-MCI compared to HC and PD-NC. Box plots with Whiskers min to max show the rCBF values in the Lt.PCu in the three groups and scatterplots show the relationship between the Auditory Verbal Learning Test (AVLT) immediate recall performance and rCBF values in the Lt.PCu in patients with PD-MCI after controlling for education and depression score. rCBF, relative cerebral blood flow; Lt, left; PCu, precuneus; HC, healthy control; PD-NC, Parkinson’s disease with normal cognition; PD-MCI, Parkinson’s disease with mild cognitive impairment. **p < 0.01; ***p < 0.001.

Figure 2

Decreased functional connectivity (FC) in the seed region of the Lt.PCu in the Rt.Caud/Put specific to PD-MCI compared to HC and PD-NC. Box plots with whiskers min to max show the FC values between the Lt.PCu and the Rt.Caud/Put in the three groups and scatterplots show the relationship between the FC strength in the two regions and WMS logical memory performances in patients with PD-MCI after controlling for education and depression score. Lt, left; Rt, right; PCu, precuneus; Caud, caudate; Put, putamen; HC, healthy control; PD-NC, Parkinson’s disease with normal cognition; PD-MCI, Parkinson’s disease with mild cognitive impairment. **p < 0.01; ***p < 0.001.