Loss of Neuromelanin in Parkinson’s Disease Correlates with Increased Iron Content within the Substantia Nigra

Motivation: Neuromelanin (NM) changes with iron content in the substantia nigra (SN) could provide a better understanding of the pathophysiology of PD. Goal(s): To evaluate changes in NM volume in the SN versus iron as a means of understanding NM degeneration and iron deposition in PD. Approach: We evaluated 342 healthy controls (HCs) and 558 PD patients with two different resolution datasets (Cohort 1 and 2) using magnetization transfer contrast imaging. Results: Both datasets show HCs with reasonable stable NM volumes in SN while the PD patients show a significant iron increase in the SN with loss of NM volume. Impact: A loss of NM volume with an increase of iron within SN demonstrates the association between NM depigmentation and iron elevation in PD, which provides insight into the role of NM and iron underlying PD pathophysiology.