T2*-weighted MRI values correlate with motor and cognitive dysfunction in Parkinson's disease

Brain iron load is one of the main neuropathologic hallmarks of Parkinson's disease (PD). Previous studies indicated that iron in the substantia nigra (SN) is related to disease duration and motor impairment. We explore, through a cross-sectional study, the association between brain iron distribution, evaluated by T2*-weighted magnetic resonance imaging (T2*), and clinical features in a cohort of patients with PD. Thirty-two patients with PD, compared with 10 control subjects, were evaluated for motor and cognitive features (attention and working memory, executive functions, language, memory, and visuospatial function). They underwent a magnetic resonance imaging protocol including T2* analysis of specific brain regions of interest to measure iron load compared with healthy control subjects. We found that iron content of the SN correlated positively with both disease duration and Unified Parkinson's Disease Rating Scale III off score. Montreal Cognitive Assessment, Spatial Span, and Graded Naming Test scores were inversely associated with iron load of the SN, whereas Wechsler Adult Intelligence Scale-IV Similarities score showed an inverse relationship with iron content in all the regions of interest examined. Our findings suggest a relationship between topographic brain iron distribution and cognitive domain impairment.