Assessment of structural brain changes in patients with type 2 diabetes mellitus using the MRI-based brain atrophy and lesion index

Patients with type 2 diabetes mellitus(T2 DM) often have cognitive impairment and structural brain abnormalities.The magnetic resonance imaging(MRI)-based brain atrophy and lesion index can be used to evaluate common brain changes and their correlation with cognitive function,and can therefore also be used to reflect whole-brain structural changes related to T2 DM.A total of 136 participants(64 men and 72 women,aged 55–86 years) were recruited for our study between January 2014 and December 2016.All participants underwent MRI and Mini-Mental State Examination assessment(including 42 healthy control,38 T2 DM without cognitive impairment,26 with cognitive impairment but without T2 DM,and 30 T2 DM with cognitive impairment participants).The total and sub-category brain atrophy and lesion index scores in patients with T2 DM with cognitive impairment were higher than those in healthy controls.Differences in the brain atrophy and lesion index of gray matter lesions and subcortical dilated perivascular spaces were found between non-T2 DM patients with cognitive impairment and patients with T2 DM and cognitive impairment.After adjusting for age,the brain atrophy and lesion index retained its capacity to identify patients with T2 DM with cognitive impairment.These findings suggest that the brain atrophy and lesion index,based on T1-weighted and T2-weighted imaging,is of clinical value for identifying patients with T2 DM and cognitive impairment.Gray matter lesions and subcortical dilated perivascular spaces may be potential diagnostic markers of T2 DM that is complicated by cognitive impairment.This study was approved by the Medical Ethics Committee of University of South China(approval No.USC20131109003) on November 9,2013,and was retrospectively registered with the Chinese Clinical Trial Registry(registration No.Chi CTR1900024150) on June 27,2019.

Chronic hypoperfusion due to intracranial large artery stenosis is not associated with cerebralβ-amyloid deposition and brain atrophy

Background:Insufficient cerebral perfusion is suggested to play a role in the development of Alzheimer disease(AD).However,there is a lack of direct evidence indicating whether hypoperfusion causes or aggravates AD pathology.We investigated the effect of chronic cerebral hypoperfusion on AD-related pathology in humans.Methods:We enrolled a group of cognitively normal patients(median age:64 years)with unilateral chronic cerebral hypoperfusion.Regions of interest with the most pronounced hypoperfusion changes were chosen in the hypoperfused region and were then mirrored in the contralateral hemisphere to create a control region with normal perfusion.11C-Pittsburgh compound-positron emission tomography standard uptake ratios and brain atrophy indices were calculated from the computed tomography images of each patient.Results:The median age of the 10 participants,consisting of 4 males and 6 females,was 64 years(47-76 years).We found that there were no differences in standard uptake ratios of the cortex(volume of interest[VOI]:P=0.721,region of interest[ROI]:P=0.241)and grey/white ratio(VOI:P=0.333,ROI:P=0.445)and brain atrophy indices(Bicaudate,Bifrontal,Evans,Cella,Cella media,and Ventricular index,P>0.05)between the hypoperfused regions and contralateral normally perfused regions in patients with unilateral chronic cerebral hypoperfusion.Conclusion:Our findings suggest that chronic hypoperfusion due to large vessel stenosis may not directly induce cerebralβ-amyloid deposition and neurodegeneration in humans.

Correlation between white matter damage and gray matter lesions in multiple sclerosis patients

We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe(superior frontal, middle frontal, precentral, and orbital gyri), right parietal lobe(postcentral and inferior parietal gyri), right temporal lobe(caudate nucleus), right occipital lobe(middle occipital gyrus), right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.

Therapeutic Effects of Myriocin in Experimental Alcohol-Related Neurobehavioral Dysfunction and Frontal Lobe White Matter Biochemical Pathology

Background & Objective: Chronic excessive alcohol consumption causes white matter degeneration with myelin loss and impaired neuronal conductivity. Subsequent rarefaction of myelin accounts for the sustained deficits in cognition, learning, and memory. Correspondingly, chronic heavy or repeated binge alcohol exposures in humans and experimental models alter myelin lipid composition leading to build-up of ceramides which can be neurotoxic and broadly inhibitory to brain functions. Methods: This study examined the effects of chronic + binge alcohol exposures (8 weeks) and intervention with myriocin, a ceramide inhibitor, on neurobehavioral functions (Open Field, Novel Object Recognition, and Morris Water Maze tests) and frontal lobe white matter myelin lipid biochemical pathology in an adult Long-Evans rat model. Results: The ethanol-exposed group had significant deficits in executive functions with increased indices of anxiety and impairments in spatial learning acquisition. Myriocin partially remediated these effects of ethanol while not impacting behavior in the control group. Ethanol-fed rats had significantly smaller brains with broadly reduced expression of sulfatides and reduced expression of two of the three sphingomyelins detected in frontal white matter. Myriocin partially resolved these effects corresponding with improvements in neurobehavioral function. Conclusion: Therapeutic strategies that support cerebral white matter myelin expression of sulfatide and sphingomyelin may help remediate cognitive-behavioral dysfunction following chronic heavy alcohol consumption in humans.

Detecting neurodegenerative pathology in multiple sclerosis before irreversible brain tissue loss sets in

Background:Multiple sclerosis(MS)is a complex chronic inflammatory and degenerative disorder of the central nervous system.Accelerated brain volume loss,or also termed atrophy,is currently emerging as a popular imaging marker of neurodegeneration in affected patients,but,unfortunately,can only be reliably interpreted at the time when irreversible tissue damage likely has already occurred.Timing of treatment decisions based on brain atrophy may therefore be viewed as suboptimal.Main body:This Narrative Review focuses on alternative techniques with the potential of detecting neurodegenerative events in the brain of subjects with MS prior to the atrophic stage.First,metabolic and molecular imaging provide the opportunity to identify early subcellular changes associated with energy dysfunction,which is an assumed core mechanism of axonal degeneration in MS.Second,cerebral hypoperfusion has been observed throughout the entire clinical spectrum of the disorder but it remains an open question whether this serves as an alternative marker of reduced metabolic activity,or exists as an independent contributing process,mediated by endothelin-1 hyperexpression.Third,both metabolic and perfusion alterations may lead to repercussions at the level of network performance and structural connectivity,respectively assessable by functional and diffusion tensor imaging.Fourth and finally,elevated body fluid levels of neurofilaments are gaining interest as a biochemical mirror of axonal damage in a wide range of neurological conditions,with early rises in patients with MS appearing to be predictive of future brain atrophy.Conclusions:Recent findings from the fields of advanced neuroradiology and neurochemistry provide the promising prospect of demonstrating degenerative brain pathology in patients with MS before atrophy has installed.Although the overall level of evidence on the presented topic is still preliminary,this Review may pave the way for further longitudinal and multimodal studies exploring the relationships between the abovementioned measures,possibly leading to novel insights in early disease mechanisms and therapeutic intervention strategies.

Stroke-like onset of brain stem degeneration presents with unique MRI sign and heterozygous NMNAT2 variant:a case report

Background:Acute-onset neurodegenerative diseases in older patients are rare clinical cases,especially when the degeneration only affects specific regions of the nervous system.Several neurological disorders have been described in which the degeneration of brain parenchyma originates from and/or primarily affects the brain stem.Clinical diagnosis in these patients,however,is often complicated due to a poor understanding of these diseases and their underlying mechanisms.Case presentation:In this manuscript we report on a 73-year-old female who had experienced a sudden onset of complex neurological symptoms that progressively worsened over a period of 2 years.Original evaluation had suggested a MRI-negative stroke as underlying pathogenesis.The combination of patient’s medical history,clinical examination and exceptional pattern of brain stem degeneration presenting as“kissing swan sign”in MR imaging was strongly suggestive of acute onset of Alexander’s disease.This leukoencephalopathy is caused by GFAP(glial fibrilary acidic protein)gene mutations and may present with brain stem atrophy and stroke-like onset of symptoms in elderly individuals.However,a pathognomonic GFAP gene mutation could not be identified by Sanger sequencing.Conclusions:After an extended differential diagnosis and exclusion of other diseases,a definite diagnosis of the patient’s condition presently remains elusive.However,whole-exome sequencing performed from patient’s blood revealed 12 potentially disease-causative heterozygous variants,amongst which several have been associated with neurological disorders in vitro and in vivo–in particular the axon degeneration-related NMNAT2 gene.

Integrated lipidomics and proteomics network analysis highlights lipid and immunity pathways associated with Alzheimer's disease

Background:There is an urgent need to understand the pathways and processes underlying Alzheimer's disease(AD)for early diagnosis and development of effective treatments.This study was aimed to investigate Alzheimer's dementia using an unsupervised lipid,protein and gene multi-omics integrative approach.Methods:A lipidomics dataset comprising 185 AD patients,40 mild cognitive impairment(MCI)individuals and 185 controls,and two proteomics datasets(295 AD,159 MCI and 197 controls)were used for weighted gene CO-expression network analyses(WGCNA).Correlations of modules created within each modality with clinical AD diagnosis,brain atrophy measures and disease progression,as well as their correlations with each other,were analyzed.Gene ontology enrichment analysis was employed to examine the biological processes and molecular and cellular functions of protein modules associated with AD phenotypes.Lipid species were annotated in the lipid modules associated with AD phenotypes.The associations between established AD risk loci and the lipid/protein modules that showed high correlation with AD phenotypes were also explored.Results:Five of the 20 identified lipid modules and five of the 17 identified protein modules were correlated with clinical AD diagnosis,brain atrophy measures and disease progression.The lipid modules comprising phospholipids,triglycerides,sphingolipids and cholesterol esters were correlated with AD risk loci involved in immune response and lipid metabolism.The five protein modules involved in positive regulation of cytokine production,neutrophil-mediated immunity,and humoral immune responses were correlated with AD risk loci involved in immune and complement systems and in lipid metabolism(the APOE ε4 genotype).Conclusions:Modules of tightly regulated lipids and proteins,drivers in lipid homeostasis and innate immunity,are strongly associated with AD phenotypes.