Study On Effects Of Vascular Risk Factors On Amnestic Mild Cognitive Impairment Patients By Diffusion Tensor Imaging

Background Alzheimer’s disease(AD)is a chronic neurodegenerative disease that usually starts slowly and worsens over time.At present,no treatments stop or reverse its progression.Mild cognitive impairment(MCI)is considered to be the first stage of AD continuous spectrum.Amnestic mild cognitive impairment(aMCI)has been confirmed to be the high-risk groups for AD.Recent studies suggest that vascular risk factors such as age,hypertension,diabetes,coronary heart disease,hyperlipidemia,smoking,drinking and carotid atherosclerosis that play an important role in the occurrence and development of AD.Diffusion tensor imaging(DTI)measures the diffusion and direction of water molecules to show the extent of white matter fibers and quantitative the damage of white matter fibers.Some research suggest that AD affects not only the gray matter but also the white matter.Therefore,we choose DTI for early detection and monitoring of disease progression and response to MCI and AD.Objective To explore the effects of VRF on cognitive function and white matter integrity in patients with aMCI by DTI,and to identify the clinical stage of AD more accurately.Methods 70 cases of aMCI group and 96 cases in healthy control group were scanned with DTI.According to the numbers of VRFs patients carry,the whole group were divided into NVRF group(without VRF),VRF1 group(with 1 VRF),VRF2 group(with 2 VRFs),VRF3 group(more than 2 VRFs).Neuropsychological tests were used to evaluate the cognitive function.Fractional anisotropy(FA)and mean diffusivity(MD)were calculated to analyze and study on effects of VRF on aMCI patients.Results 1.Based on brain white matter atlas,FA values of brain regions of aMCI patients showed no significant difference(p>0.05).However,the difference of MD values of bilateral anterior thalamic radiation,forceps minor,left inferior fronto-occipital fasciculus,bilateral uncinate fasciculus were significant(all p<0.05).About the VRF effects,significant lower FA were found in the left anterior thalamic radiation,right corticospinal tract,right cingulate gyrus,left hippocampus,forceps major,forceps minor,bilateral inferior fronto-occipital fasciculus,bilateral inferior longitudinal fasciculus,bilateral superior longitudinal fasciculus(all p<0.05).We also found that MD was significantly increased in the left cingulate gyrus,forceps minor,right inferior fronto-occipital fasciculus,left inferior longitudinal fasciculus(p<0.05).2.In addition,integrity of bilateral anterior thalamic radiation(MD:left,r=-0.275,p=0.000;right,r=-0.264,p=0.001)and bilateral uncinate fasciculus(MD:left,r=-0.287,p=0.000;right,r=-0.291,p=0.000)were associated with memory function in aMCI patients.Whilst,integrity in the right anterior thalamic radiation(MD:r=-0.23,p=0.003)and bilateral uncinate fasciculus(MD:left,r=-0.29,p=0.000;right,r=-0.197,p=0.012)were associated with visuospatial function.Integrity in bilateral anterior thalamic radiation(MD:left,r=-0.253,p=0.001;right,r=-0.234,p=0.003)and bilateral uncinate fasciculus(MD:left,r=-0.256,p=0.001;right,r=-0.161,p=0.039)were associated with information processing speed.Integrity of bilateral anterior thalamic radiation(MD:left,r=-0.225,p=0.004;right,r=-0.206,p=0.008)and bilateral uncinate fasciculus(MD:left,r=-0.225,p=0.004;right,r=-0.171,p=0.029)were associated with executive function.About the VRF effects,integrity of left uncinate fasciculus(MD:r=-0.17,p=0.030)was associated with memory function and the left uncinate fasciculus(MD:r=-0.160,p=0.042)was associated with executive function.Conclusion aMCI patients had cognitive impairment in many fields including episodic memory,information processing speed,executive function and visuospatial function.Our findings showed that there was a wide range of white matter damage in aMCI patients.VRF1 subgroup damaged most,which may be a structural plasticity mechanism of cerebral white matter damage.