The Neuropsychological Features And Proton Magnetic Resonance Spectroscopy Research Of Different Mild Cognitive Impairment Subtypes

Objective: First, to investigate the neuropsychological features of different mildcognitive impairment (MCI) subtypes. Second, to research the brain metabolismchanges in different MCI subtypes by proton magnetic resonance spectroscopy(1HMRS) and the relationship between the metabolism ratios and cognitive impairment,and further confirm the role of1H MRS in identifying MCI subtypes.Methods: We tested the objects of interest by using a series of neuropsychologicalscreens including Mini-Mental State Examination (MMSE), Cambridge CognitiveExamination Chinese version (CAMCOG-C) and Geriatric Depression Scale (GDS),and then compared the neuropsychological features among the amnestic MCI (A-MCI),vascular MCI (V-MCI) and Parkinson’s disease MCI (PD-MCI). Fourteen patients withA-MCI, twelve with V-MCI and seventeen normal control elderly (NC) were evaluatedby the single voxel1HMRS on a3.0-T-scanner (Signa; GE Medical Systems,Milwaukee, WI) with the regions of interest (ROIs) located in the frontal lobe, basalganglia and hippocampus of the dominant hemisphere. The metabolism ratios of eachROIs including NAA/Cr, Cho/Cr and MI/Cr were automatically calculated at the endof each spectra acquisition. We compared changes of the1H MRS ratios in A-MCI andV-MCI. A correlation analysis was also performed with the Pearson momentcorrelation for MRS index and cognitive scores.Results:(1) No significant difference was observed between A-MCI and V-MCI in theage, sex and education years. The prevalence of hypertension significantly evaluated in A-MCI and V-MCI.(2) There were multi-domain cognitive impairment in all A-MCI,V-MCI and PD-MCI group. A-MCI had a significant lower score in recent memoryand learning memory. The cognitive of praxis significantly impaired in V-MCI. InPD-MCI group, there was not only a lower score in recent memory and learningmemory, but also a decreased function of remote memory and praxis.(3) In V-MCIgroup, a significant lower NAA/Cr ratio in the left frontal lobe was observed comparedto NC and A-MCI, and positively correlated with CAMCOG-C score and cognitiveimpairment of orientation, language comprehension and praxis. The NAA/Cr ratio inA-MCI reduced significantly in the left hippocampus compared to NC and V-MCI, andpositively correlated with recent memory decline. There was no significant differenceof any metabolic ratio in the left basal ganglia among the three groups.Conclusions:(1) The features of cognitive impairment in3subtypes here were allmultiple domains. Different subtypes impaired in different domains. There were greatchanges in memory in A-MCI, execution in V-MCI, and both memory and execution inPD-MCI.(2) The NAA/Cr ratio was significantly reduced in hippocampus in A-MCIand significantly decreased in frontal lobe in V-MCI. The reduced NAA/Cr waspositively correlated with the cognitive function.1HMRS may be a useful tool fordifferentiating A-MCI and V-MCI.