The characteristics of subcortical nuclei iron deposition in de novo Parkinson disease with mild cognitive impairment using quantitative sensitivity mapping

Objective To explore the characteristics of subcortical nuclei iron deposition in de novo Parkinson disease (PD) patients with mild cognitive impairment (MCI) by using quantitative sensitivity mapping (QSM), and the correlation between QSM values (QSMs) and cognitive function in PD patients.

Methods From October 2016 to December 2017, 34 de novo PD patients in Zhongshan Hospital, Fudan University were collected.Patients were divided into group PD-MCI (PD with MCI, n=12) and group PD-NC (PD with normal cognition, n=22), and other 25 healthy people were chosen as control group (HCs).The QSMs of substantia nigra (SN), red nucleus (RN), putamen (PU), head of caudate nucleus (CN), globus pallidus (GP) and dentate nucleus (DN) among three groups were compared.Furtherly, the correlations between QSMs in each nucleus and cognitive scales were analyzed.

Results The QSMs in the bilateral SN, bilateral RN, bilateral PU, and left DN in group PD-MCI were significantly higher than those in group HCs (P < 0.05).QSMs in the right RN and right PU in group PD-MCI were significantly higher than those in group PD-NC (P < 0.05).Correlation analyses showed that QSMs in the bilateral GP and PU were positively correlated with the Trail Making Test-A (right GP: r=0.555, P=0.005;left GP: r=0.470, P=0.020;right PU: r=0.479, P=0.018;left PU: r=0.430, P=0.036), QSMs in the right RN and left CN were negatively correlated with Animal Fluency Test (right RN: r=﹣0.457, P=0.025;left CN: r=﹣0.524, P=0.010), and QSMs in the right PU were negatively correlated with Boston Naming Test (r=﹣0.445, P=0.033).Multiple linear regression analysis showed that the QSM value of right GP had a significant impact on TMT-A (P=0.005).

Conclusions The extensively abnormal iron deposition were found in subcortical nuclei in PD-MCI by using the QSM, and the iron deposition was associated with impaired attention and language functions in PD patients, suggesting that abnormal iron accumulation may participate in the pathophysiological process of cognitive dysfunction in PD.