The Research Of Iron Deposition In Brain And Its Correlation With Cognitive Impairment In Patients With Idiopathic Rapid Eye Movement Sleep Behavior Disorder Based On Quantitative Susceptibility Mapping

Objective To evaluate features of cognitive function in iRBD patients;To determine the characteristics of iron deposition in the brain of patients suffering from idiopathic Rapid-eye-movement sleep Behavior Disorder(iRBD)by Quantitative Susceptibility Mapping(QSM);To explore the correlation between cognitive function and the distribution of iron deposition in the gray matter nuclei of the patients with iRBD.To explore the pathological mechanism of cognitive impairment in iRBD patients and to provide new therapeutic targets and theoretical basis for posponing the change from iRBD to neurodegenerative disease.Methods Continuously recruiting 24 iRBD patients from Tianjin Medical University General Hospital from September 2014 to May 2019.All the patinets have v-PSG examination and were diagnosed according to the standards described in the International classification of sleep disorders(ICSD-3)criteria(Sateia,2014)and v-PSG examination as case group(iRBD group).Randomly selecting 25 non-RBD patients with suitable gender,age and education level as healthy control group(HC group).After informed consent in two groups,we collect their general information including gender,age,education;assess the neuropsychological function in different aspects including 1.visualspatial ability assessment(Rey-Osterrieth complex figure),2.attention/execution capability assessment(Trial making test,Stroop color word test,Verbal fluency test),3.learning and memory capability assessment(Auditory verbal learning test,Rey complex graphics memory test),4.language skills assessment(Boston naming test).After analysis and calculation,the characteristics of cognitive function in iRBD patients were obtained.Excluding the previous metal stents,dentures,claustrophobia and so on,fourteen iRBD patients and 17 healthy controls were selected to have a conventional MRI including T1 weighted image(T1WI)and T2 weighted image(T2WI)and unfiltered SWI scan on 3.0T MRI system.Susceptibility was measured in the regions of interest in the deep nucleus of the brain including bilateral caudate nucleus,bilateral globus pallidus,bilateral putamen,bilateral thalamus,bilateral red nucleus,the bilateral substantia nigra and bilateral dentate nucleus and used to compare between patients with iRBD patients and healthy controls by two independent samples t-testand,and the correlation was analyzed with cognitive function.Comparison:1.Differences in cognitive function between iRBD group and HC group;2.Difference in susceptibility in different brain structures between iRBD group and HC group;3.Correlation between susceptibility in different brain structures and cognitive function in iRBD group.Results1.Compared with HC group,iRBD group showed a decreasing trend in attention/execution ability and language ability,but there seems to be no statistically significant difference,P > 0.05.And visual spatial ability and learning and memory learning ability were significantly decreased in iRBD group(P <0.05);2.In iRBD patients,the susceptibility of the right substantia nigra and right dentate nucleus was statistically higher than that in healthy controls,P < 0.05;3.In iRBD patients,.the susceptibility of the bilateral caudate nucleus was negatively correlated with the average cognitive function(the left caudate nucleus P<0.05,r=-0.598;the right caudate nucleus P<0.05,r=-0.616);the left caudate nucleus was negatively correlated with attention/executive function(P<0.05,r=-0.542);the susceptibility of the bilateral putamen was negatively correlated with the average cognitive function(the left putamen P<0.05,r=-0.576;the right putamen P<0.05,r=-0.617);the susceptibility of the bilateral putamen was negatively correlated with the visualspatial ability(the left putamen P<0.05,r=-0.638;the right putamen P<0.05,r=-0.591);3.3 In iRBD patients,the attention/execution ability was negatively correlated with the susceptibility of the right red nucleus(P<0.05,r=0.545).the susceptibility of the right dentate nucleus was negatively correlated with memory learning function(P<0.05,r=-0.554);Conclusion1.The areas of cognitive impairment in iRBD patients were visual spatial function and memory learning ability.The increase of iron deposition in the caudate nucleus, putamen and the dentate nucleus may aggravate the cognitive impairment in iRBD patients.2.QSM can provide an an accurate definition of the distribution of magnetic biomaterials in MRI.The increase of iron deposition in substantia nigra and cerebellar dentate nucleus in patients with iRBD may aggravate the changes from iRBD to neurodegenerative diseases,and may be one of the early imaging markers for the transformation of iRBD into neurodegenerative disease.3.The modification therapy for iron metabolism may be a new therapeutic target for iRBD,which may help to delay the neurodegeneration and cognitive impairment of iRBD.