Objective: To investigate how brain iron deposition relates to visual function and dementia risk in Parkinson’s Disease (PD).

Background: Oxidative stress due to brain iron accumulation has been implicated as a pathomechanism in PD[1]. Recent work has highlighted a novel MRI contrast that maps brain iron deposition – quantitative susceptibility mapping (QSM) – as an in vivo biomarker for PD[2]. Visuo-perceptual deficits have been linked to cognitive capabilities in PD[3] and may constitute a way to identify patients at higher risk of dementia. We will relate visuo-perceptual abilities and QSM data to scores of dementia risk in PD. Based on this, we expect patients at higher risk of dementia to have poorer visual scores and increased iron deposition in occipital and posterior parietal cortex.

Method: 100 PD patients and 37 age-matched controls underwent detailed neuropsychology, visuo-perceptual measures (e.g., cats and dogs task[3]), assessment of PD (MDS-UPDRS) and susceptibility-weighted and structural T1 MRI scans. Risk of cognitive involvement was calculated using a clinical algorithm (combining age at onset, MMSE, education, motor score, gender, depression)[4]. QSM images were reconstructed from complex multi-channel susceptibility-weighted data using a multi-scale dipole inversion algorithm[5], followed by coregistration and standardization with T1 images and whole brain and regional statistical QSM analysis[6]. We will determine whether brain iron deposition differs between PD patients at high and low risk of dementia and controls.

Results: Age did not differ between PD patients (64.5±7.7 years) and controls (66.1±9.4 years). Patients were assigned as either low risk or high risk based on a median split of the risk score[2]. There was no difference in disease duration, gender, motor, sleep or olfaction scores or levodopa dose between high and low risk patients. Brain iron deposition in patients at high and low risk of dementia, and with high and low visuo-perceptual scores will be presented in whole brain and regional analyses of posterior parietal regions, occipital regions and precuneus.

Conclusion: QSM in PD may be able to effectively map functional changes in brain regions involved in visual processing before atrophy takes place. In combination with visual testing this could be used to predict which patients are likely to develop dementia, facilitating directed treatment plans.

References: 1. Li, W., Jiang, H., Song, N. & Xie, J. Oxidative stress partially contributes to iron-induced alpha-synuclein aggregation in SK-N-SH cells. Neurotox. Res. 19, 435–442 (2011). 2. Acosta-Cabronero, J. et al. The whole-brain pattern of magnetic susceptibility perturbations in Parkinson’s disease. Brain 140, 118–131 (2017). 3. Weil, R. S. et al. Assessing cognitive dysfunction in Parkinson’s disease: An online tool to detect visuo-perceptual deficits. Mov. Disord. 33, 544–553 (2018). 4. Liu, G. et al. Prediction of cognition in Parkinson’s disease with a clinical–genetic score: a longitudinal analysis of nine cohorts. Lancet Neurol. 16, 620–629 (2017). 5. Acosta-Cabronero, J. et al. A robust multi-scale approach to quantitative susceptibility mapping. Neuroimage 183, 7–24 (2018). 6. Acosta-Cabronero, J., Betts, M. J., Cardenas-Blanco, A., Yang, S. & Nestor, P. J. In Vivo MRI Mapping of Brain Iron Deposition across the Adult Lifespan. J. Neurosci. 36, 364–374 (2016).

« Back to 2019 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/using-quantitative-susceptibility-mapping-to-predict-dementia-in-parkinsons-disease/