Quantitative analysis of brain metabolites in patients with non-dementia vascular cognitive impairment and mild cognitive impairment

Abstract

Objective To investigate metabolite changes in the brain of patients with nondementia vascular cognitive impairment (VCIND) and mild cognitive impairment (MCI) using magnetic resonance spectroscopy (MRS). Methods Twenty-five patients with VCIND,21 ones with MCI and 30 normal controls (NC) were participated in this experiment.The absolute concentrations of N-acetyl aspartate (NAA),choline (Cho),myo-inositol (MI),creatine (Cr) and the metabolite ratios of NAA/Cr,Cho/Cr,MI/Cr,NAA/MI and NAA/Cho were measured bilaterally in the posterior cingulate gyrus (PCG),white matter of the occipital lobe (OLWM),dorsal thalamus (DT),and white matter of the frontal lobe (FLWM) by multivoxel MRS.The metabolite concentrations were quantified and post-processed using SAGE 7.0 and LCModel software. Results (1) Compared with the NC group,VCIND patients displayed higher Cho level in the left FLWM[ (1.9±0.4) mmol/L,P<0.05],MCI patients displayed an elevated concentration of MI in the right PCG[ (6.2±1.1) mmol/ L,P<0.05]and lower NAA level in the bilateral PCG[left (6.9±1.1) mmol/ L,right (7.0±1.4) mmol/L,all P<0.05) ].The NAA/Cr ratio in the bilateral DT and bilateral FLWM with VCIND patients (left DT of 1.3±0.3,right DT of 1.2±0.3,left FLWM of 1.3±0.2,right FLWM of 1.1±0.2,all P<0.05) and in the bilateral PCG with MCI patients (left 1.2±0.2,right 1.3±0.3;all P<0.05) showed lower than NC subjects. (2) The patients with VCIND displayed lower NAA/Cho ratio in left OLWM and right DT (left OLWM of 4.6±1.0,right DT of 5.2±1.4,all P<0.05) than either NC or MCI subjects,while it displayed a significantly lower NAA/Cho ratio in the bilateral FLWM (left 4.3±1.1,right 4.2±0.9,all P<0.01) than NC subjects. (3) The NAA/MI ratio in the bilateral OLWM (left 1.6±0.3,right 1.3±0.4,all P<0.05) with MCI patients showed lower than either NC subjects or VCIND patients,while the MCI patients display a significantly lower NAA/MI ratio in the bilateral PCG (left 1.2±0.3,right 1.2±0.4,all P<0.01) than NC subjects. Conclusions Both VCIND and MCI patients may have metabolite dysfunctions in different regions of the brain,it may provide efficient information for clinical diagnosis,preventing and treating in the early stages of dementia. Key words: Magnetic resonance spectroscopy; Quantitative evaluation; Vascular cognitive impairment no dementia; Mild cognitive impairment