Multimodal Brain Magnetic Resonance Imaging Study Of Alzheimer’s Disease And Amnestic Mild Cognitive Impairment

Background:Alzheimer’s disease(AD)is a common neurodegenerative disease that usually begins in people over 60 years of age.The onset of AD is concealed,and the symptoms gradually develop and progressively worsen.The symptoms are memory and cognitive decline,and the prognosis is poor.Amnesia mild cognitive impairment(a MCI)refers to mild cognitive impairment with pathological changes in AD,and is a subtype of mild cognitive impairment(MCI)MCI.It has a higher chance to convert to AD.At the same time when clinical symptoms appear,the brain structure changes accordingly.These two interacts each other and affects the course of disease.Aim:We conducted a study on an elderly cohort with different cognitive impairment,using a battery of neuropsychological tests and susceptibility weighted image(SWI)and structural magnetic resonance imaging(s MRI)to explore specific neuroimaging characteristics of the a MCI and AD.(1)SWI was used to explore the differences in cerebral microbleeds among the elderly with different levels of cognitive function.(2)Tensor-based morphometry(TBM)is the tool of analyzing s MRI to identify specific atrophic brain regions and specific brain regions associated with decreased neurocognitive function in a MCI.The results of this study provide clues and evidence for early clinical diagnosis and intervention.Methods:1.For the study of cerebral microbleeds characteristics,we investigated 18AD(AD group),28 a MCI(a MCI group)and 30 age-matched normal control elderly(NC group)were recruited in the study.The bilateral frontal lobe,parietal lobe,occipital lobe,temporal lobe,and thalamus were manually mapped on 3D-MR imaging.SWIs and neuropsychological tests were collected by trained neuropsychiatrists.The location of microbleeds was recorded in the brain according to the SWIs.The number of cases with microbleeds and the number of microbleeds in each lobe were calculated and compared among groups.2.For the study of brain atrophy characteristics,we investigated 52 a MCI participants(a MCI group)and 103 age and sex-matched NC participants(NC group).We collected the data of general demographic information and s MRI.We then utilized TBM to create Jacobian Determinant(JD)maps and assessed differences in brain volume between two groups.Participants also completed a neuropsychological battery.Using linear regression modeling we tested whether regional brain volume correlated with cognitive performance scores.Results:1.Susceptibility-weighted image: Subjects with different levels of cognitive function had different amounts of microbleeds,and patients with low levels of cognitive function had more microbleeds(p <0.05).Significant differences on case number with microbleeds were found between AD and NC in the frontal lobe,the temporal lobe and whole brain,and between a MCI and NC in the frontal lobe.It also showed significant difference among three groups in the frontal lobe,the temporal lobe and whole brain.For the microbleeds counts,significant differences were found between AD and NC in the frontal lobe and the temporal lobe and between AD and NC in the frontal lobe(P=0.044).It also had significant differences among three groups in the frontal lobe,the temporal lobe and whole brain.2.SMRI study: Compared with normal controls,a MCI subjects demonstrated significant atrophy in MTL,precentral gyrus,postcentral gyrus,middle temporal lobe,fusiform gyrus,thalamus,caudate,cerebellum and the banks of the superior temporal sulcus(bankssts).Cognitive performance scores significantly correlated with the volume of MTL,entorhinal cortex,caudal middle frontal lobe,putamen,amygdala,and pallidum.Conclusions:1.The AD group and a MCI group has more significant microbleeds in frontal and parietal lobes in comparison to NC.The quantization of cerebral microbleeds may be a potential biomarker for AD diagnosis.2.Using TBM we identified structural changes in several brain regions that may be involved in the pathological processes underlying a MCI.These structural alternations should be investigated as targets for early screening.