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Neuroimage Clin. 2018 Jul 27;20:365-373. doi: 10.1016/j.nicl.2018.07.028. eCollection 2018.

Quantitative susceptibility mapping as an indicator of subcortical and limbic iron abnormality in Parkinson's disease with dementia.

Author information

1
Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong.
2
Philips Healthcare, Hong Kong.
3
Department of Psychiatry, Yale University, New Haven, CT, United States,; Department of Psychiatry, The University of Hong Kong, Hong Kong.
4
Department of Psychiatry, The University of Hong Kong, Hong Kong,; Raffles Counselling Centre, Raffles Hospital, Singapore.
5
Department of Psychiatry, The University of Hong Kong, Hong Kong,; Department of Forensic and Neurodevelopmental Science, King's College London, London, United Kingdom,; South London and Maudsley NHS Foundation Trust, United Kingdom.
6
Division of Neurology, Department of Medicine, The University of Hong Kong, Hong Kong.
7
Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong,; State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong,; Alzheimer's Disease Research Network, The University of Hong Kong, Hong Kong. Electronic address: makkf@hku.hk.

Abstract

Late stage Parkinson's disease (PD) patients were commonly observed with other non-motor comorbidities such as dementia and psychosis. While abnormal iron level in the substantia nigra was clinically accepted as a biomarker of PD, it was also suggested that the increased iron deposition could impair other brain regions and induce non-motor symptoms. A new Magnetic Resonance Imaging (MRI) called Quantitative Susceptibility Mapping (QSM) has been found to measure iron concentration in the grey matter reliably. In this study, we investigated iron level of different subcortical and limbic structures of Parkinson's disease (PD) patients with and without dementia by QSM. QSM and volumetric analysis by MRI were performed in 10 PD dementia (PDD) patients (73 ± 6 years), 31 PD patients (63 ± 8 years) and 27 healthy controls (62 ± 7 years). No significant differences were observed in the L-Dopa equivalent dosage for the two PD groups (p = 0.125). Putative iron content was evaluated in different subcortical and limbic structures of the three groups, as well as its relationship with cognitive performance. One-way ANCOVA with FDR adjustment at level of 0.05, adjusted for age and gender, showed significant group differences for left and right hippocampus (p = 0.015 & 0.032, respectively, BH-corrected for multiple ROIs) and right thalamus (p = 0.032, BH-corrected). Post-hoc test with Bonferroni's correction suggested higher magnetic susceptibility in PDD patients than healthy controls in the left and right hippocampus (p = 0.001 & 0.047, respectively, Bonferroni's corrected), while PD patients had higher magnetic susceptibility than the healthy controls in right hippocampus and right thalamus (p = 0.006 & 0.005, respectively, Bonferroni's corrected). PDD patients also had higher susceptibility than the non-demented PD patients in left hippocampus (p = 0.046, Bonferroni's corrected). The magnetic susceptibilities of the left and right hippocampus were negatively correlated with the Mini-Mental State Examination score (r = -0.329 & -0.386, respectively; p < 0.05). This study provides support for iron accumulation in limbic structures of PDD and PD patients and its correlation with cognitive performance, however, its putative involvement in development of non-motor cognitive dysfunction in PD pathogenesis remains to be elucidated.

KEYWORDS:

Amygdala; Dementia; Hippocampus; Iron deposition; Magnetic resonance imaging; Parkinson's disease; Quantitative susceptibility mapping

PMID:
30128274
PMCID:
PMC6096006
DOI:
10.1016/j.nicl.2018.07.028
[Indexed for MEDLINE]
Free PMC Article

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