Reduced Glucose Metabolism Research Articles

The relationship between brain glucose metabolism and insulin resistance in subjects with normal cognition - a study based on 18F-FDG PET.

Insulin resistance can increase the risk of cognitive dysfunction and dementia. Our purpose is to use 18F-FDG PET imaging to explore the effect of insulin resistance on brain glucose metabolism in cognitively normal subjects. A total of 189 cognitively normal subjects who underwent PET examinations were enrolled. The homeostasis model assessment of insulin resistance (HOMA-IR) was used to evaluate the presence of insulin resistance. Multivariate linear regression and generalized additive models were used to analyze the association between HOMA-IR and glucose metabolism in the whole brain and evaluate the effects of various covariates. The SPM12 software was used to evaluate the regional effect of insulin resistance on brain glucose metabolism. After being fully adjusted for confounding factors, HOMA-IR showed an approximately linear negative correlation with brain glucose metabolism (β = -0.219, T = -3.331, P = 0.021). Compared with normal subjects, insulin-resistant subjects had reduced glucose metabolism in bilateral middle temporal gyrus, bilateral middle frontal gyrus, right precentral gyrus, right inferior frontal gyrus, right cuneiform lobe and bilateral cerebellar regions. In cognitively normal subjects, systemic insulin resistance has a significant effect on brain glucose metabolism. 18F-FDG brain PET imaging could be helpful for the early diagnosis and treatment of changes in brain glucose metabolism caused by insulin resistance.

C.2 The use of magnetic resonance guided focused ultrasound for refractory psychiatric illness

Background: Obsessive compulsive disorder (OCD) and major depressive disorder (MDD) are common, often refractory, neuropsychiatric conditions for which new treatment approaches are urgently needed. Magnetic resonance guided focused ultrasound (MRgFUS) is a novel surgical technique permitting incisionless ablative neurosurgery. Methods: We examined the safety profile, clinical response, and imaging correlates of MRgFUS anterior capsulotomy (MRgFUS-AC) in patients with refractory OCD (n=7) and MDD (n = 10). Results: There were no serious adverse clinical or radiographic events. 5/7 OCD patients and 3/10 MDD patients met pre-established clinical response criteria. Neurocognitive performance improved on several measures of executive function (p<0.05). By 6 months, there were significant reductions in cerebral glucose metabolism, and reductions in the bilateral tracts connecting the thalamus with the orbitofrontal cortices, anterior cingulate cortex (p<0.05). Preoperative functional connectivity between the right ventral striatum and hippocampus was predictive of eventual clinical response (p-FDR<0.05). Conclusions: MRgFUS-AC is safe and demonstrates important evidence of efficacy in treatment resistant psychiatric disease, particularly OCD. The procedure was associated with structural and metabolic changes in brain networks implicated in affective regulation, Resting-state fMRI offers the ability to predict response, and potentially select patients most likely to improve.

Changes of cerebral network activity after invasive stimulation of the mesencephalic locomotor region in a rat stroke model

Motor deficits after stroke reflect both, focal lesion and network alterations in brain regions distant from infarction. This remote network dysfunction may be caused by aberrant signals from cortical motor regions travelling via mesencephalic locomotor region (MLR) to other locomotor circuits. A method for modulating disturbed network activity is deep brain stimulation. Recently, we have shown that high frequency stimulation (HFS) of the MLR in rats has restored gait impairment after photothrombotic stroke (PTS). However, it remains elusive which cerebral regions are involved by MLR-stimulation and contribute to the improvement of locomotion. Seventeen male Wistar rats underwent photothrombotic stroke of the right sensorimotor cortex and implantation of a microelectrode into the right MLR. 2-[18F]Fluoro-2-deoxyglucose ([18F]FDG)-positron emission tomography (PET) was conducted before stroke and thereafter, on day 2 and 3 after stroke, without and with MLR-HFS, respectively. [18F]FDG-PET imaging analyses yielded a reduced glucose metabolism in the right cortico-striatal thalamic loop after PTS compared to the state before intervention. When MLR-HFS was applied after PTS, animals exhibited a significantly higher uptake of [18F]FDG in the right but not in the left cortico-striatal thalamic loop. Furthermore, MLR-HFS resulted in an elevated glucose metabolism of right-sided association cortices related to the ipsilateral sensorimotor cortex. These data support the concept of diaschisis i.e., of dysfunctional brain areas distant to a focal lesion and suggests that MLR-HFS can reverse remote network effects following PTS in rats which otherwise may result in chronic motor symptoms.

TIGIT Induces (CD3+) T Cell Dysfunction in Colorectal Cancer by Inhibiting Glucose Metabolism.

T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) is an immunosuppressive receptor expressed on the surface of immune cells, suppressing immune responses by activating the intracellular negative regulatory signals. TIGIT plays an important role in the pathogenesis of various tumors, but its immune escape in colorectal cancer remains unclear. We found that the proportion of CD3+TIGIT+ T cells was increased in peripheral blood and cancer tissue in colorectal cancer patients when compared with the healthy donors. These cells exhibited functional defects, low proliferative activity, impaired cytokine production and reduced glucose metabolism. A strong association was also observed between the elevated TIGIT expression and poor prognosis in this cohort. In the in vitro co-culture assays of T cells and tumor cells, the suppressed glucose metabolic activity of T cells was reversed by TIGIT blockade. In addition, this blockade induced the apoptosis and reduced G2/M transit in tumor cells. The antitumor efficacy of TIGIT Ab therapy was further demonstrated in a human colorectal xenograft mice model while co-blockers of TIGIT and PD-1 exhibited synergistic suppressing effects on tumor growth. These results suggest that while TIGIT induces CD3+ T cell dysfunction in colorectal cancer, co-targeting TIGIT and PD-1 can lead to an effective antitumor response and may serve as a novel therapeutic strategy for colorectal patients.

Simultaneous PET/fMRI Detects Distinctive Alterations in Functional Connectivity and Glucose Metabolism of Precuneus Subregions in Alzheimer's Disease.

As a central hub in the interconnected brain network, the precuneus has been reported showing disrupted functional connectivity and hypometabolism in Alzheimer’s disease (AD). However, as a highly heterogeneous cortical structure, little is known whether individual subregion of the precuneus is uniformly or differentially involved in the progression of AD. To this end, using a hybrid PET/fMRI technique, we compared resting-state functional connectivity strength (FCS) and glucose metabolism in dorsal anterior (DA_pcu), dorsal posterior (DP_pcu) and ventral (V_pcu) subregions of the precuneus among 20 AD patients, 23 mild cognitive impairment (MCI) patients, and 27 matched cognitively normal (CN) subjects. The sub-parcellation of precuneus was performed using a K-means clustering algorithm based on its intra-regional functional connectivity. For the whole precuneus, decreased FCS (p = 0.047) and glucose hypometabolism (p = 0.006) were observed in AD patients compared to CN subjects. For the subregions of the precuneus, decreased FCS was found in DP_pcu of AD patients compared to MCI patients (p = 0.011) and in V_pcu for both MCI (p = 0.006) and AD (p = 0.008) patients compared to CN subjects. Reduced glucose metabolism was found in DP_pcu of AD patients compared to CN subjects (p = 0.038) and in V_pcu of AD patients compared to both MCI patients (p = 0.045) and CN subjects (p < 0.001). For both FCS and glucose metabolism, DA_pcu remained relatively unaffected by AD. Moreover, only in V_pcu, disruptions in FCS (r = 0.498, p = 0.042) and hypometabolism (r = 0.566, p = 0.018) were significantly correlated with the cognitive decline of AD patients. Our results demonstrated a distinctively disrupted functional and metabolic pattern from ventral to dorsal precuneus affected by AD, with V_pcu and DA_pcu being the most vulnerable and conservative subregion, respectively. Findings of this study extend our knowledge on the differential roles of precuneus subregions in AD.

Multimodal Imaging and Visual Evoked Potentials Reveal Key Structural and Functional Features That Distinguish Symptomatic From Presymptomatic Huntington's Disease Brain.

Huntington's disease (HD) is a progressive neurodegenerative disorder characterized by motor, cognitive, and psychiatric abnormalities. Currently, matched analyses of structural and functional differences in the brain from the same study cohort and, specifically, in HD patients from an ethnically diverse Indian population are lacking. Such findings aid in identifying noninvasive and sensitive imaging biomarkers. The aim of the study was to understand the structural and functional differences between HD and control brain, and presymptomatic and symptomatic HD brain in the Indian population. Seventeen HD (11 symptomatic HD [S-HD] and six presymptomatic HD [P-HD], with comparable CAG repeats), and 12 healthy controls were examined. Macrostructural (volume), microstructural (diffusivity), and functional (neurochemical levels and glucose metabolism) imaging of the brain was done along with the determination of visual latencies. HD brain showed increased intercaudate distance; significant subcortical volumetric loss; reduced fractional anisotropy; increased mean, axial, and radial diffusivity; lower levels of total N-acetyl aspartate; elevated total choline levels; and reduced glucose metabolism compared with control brain. Interestingly, compared with P-HD, S-HD patients demonstrated a strong inverse correlation between age at onset and CAG repeat length, and prolonged P100 latency. In addition, caudate and putamen in S-HD brain showed significant volumetric loss and increased diffusivity compared with P-HD brain. HD brain showed distinct macrostructural, microstructural, and functional differences compared with control brain in the Indian population. Interestingly, patients with S-HD had a significant volumetric loss, increased diffusivity, altered neurochemical profile, and delayed P100 latency compared with P-HD patients. Examining these alterations clinically could aid in monitoring the progression of HD.

Peptide Adjuvant to Invigorate Cytolytic Activity of NK Cells in an Obese Mouse Cancer Model.

Cancer patients who are overweight compared to those with normal body weight have obesity-associated alterations of natural killer (NK) cells, characterized by poor cytotoxicity, slow proliferation, and inadequate anti-cancer activity. Concomitantly, prohibitin overexpressed by cancer cells elevates glucose metabolism, rendering the tumor microenvironment (TME) more tumor-favorable, and leading to malfunction of immune cells present in the TME. These changes cause vicious cycles of tumor growth. Adoptive immunotherapy has emerged as a promising option for cancer patients; however, obesity-related alterations in the TME allow the tumor to bypass immune surveillance and to down-regulate the activity of adoptively transferred NK cells. We hypothesized that inhibiting the prohibitin signaling pathway in an obese model would reduce glucose metabolism of cancer cells, thereby changing the TME to a pro-immune microenvironment and restoring the cytolytic activity of NK cells. Priming tumor cells with an inhibitory the prohibitin-binding peptide (PBP) enhances cytokine secretion and augments the cytolytic activity of adoptively transferred NK cells. NK cells harvested from the PBP-primed tumors exhibit multiple markers associated with the effector function of active NK cells. Our findings suggest that PBP has the potential as an adjuvant to enhance the cytolytic activity of adoptively transferred NK cells in cancer patients with obesity.

Regional glucose metabolic decreases with ageing are associated with microstructural white matter changes: a simultaneous PET/MR study.

Human ageing is associated with a regional reduction in cerebral neuronal activity as assessed by numerous studies on brain glucose metabolism and perfusion, grey matter (GM) density and white matter (WM) integrity. As glucose metabolism may impact energetics to maintain myelin integrity, but changes in functional connectivity may also alter regional metabolism, we conducted a cross-sectional simultaneous FDG PET/MR study in a large cohort of healthy volunteers with a wide age range, to directly assess the underlying associations between reduced glucose metabolism, GM atrophy and decreased WM integrity in a single ageing cohort. In 94 healthy subjects between 19.9 and 82.5years (mean 50.1 ± 17.1; 47M/47F, MMSE ≥ 28), simultaneous FDG-PET, structural MR and diffusion tensor imaging (DTI) were performed. Voxel-wise associations between age and grey matter (GM) density, RBV partial-volume corrected (PVC) glucose metabolism, white matter (WM) fractional anisotropy (FA) and mean diffusivity (MD), and age were assessed. Clusters representing changes in glucose metabolism correlating significantly with ageing were used as seed regions for tractography. Both linear and quadratic ageing models were investigated. An expected age-related reduction in GM density was observed bilaterally in the frontal, lateral and medial temporal cortex, striatum and cerebellum. After PVC, relative FDG uptake was negatively correlated with age in the inferior and midfrontal, cingulate and parietal cortex and subcortical regions, bilaterally. FA decreased with age throughout the entire brain WM. Four white matter tracts were identified connecting brain regions with declining glucose metabolism with age. Within these, relative FDG uptake in both origin and target clusters correlated positively with FA (0.32 ≤ r ≤ 0.71) and negatively with MD (- 0.75 ≤ r ≤ - 0.41). After appropriate PVC, we demonstrated that regional cerebral glucose metabolic declines with age and that these changes are related to microstructural changes in the interconnecting WM tracts. The temporal course and potential causality between ageing effects on glucose metabolism and WM integrity should be further investigated in longitudinal cohort PET/MR studies.

Glucose transporters in Alzheimer's disease

BackgroundPhysiological brain function depends on tight glucose regulation, including transport and phosphorylation, the first step in its metabolism. Impaired glucose regulation is increasingly implicated in the pathophysiology of Alzheimer's disease (AD). Glucose hypometabolism in AD may be at least partly due to impaired glucose transport at the blood-brain barrier (BBB). Glucose transporters (GLUTs) are an integral component of the BBB. There is evidence of a significant reduction in vascular and non-vascular forms of GLUT1 and GLUT3 in AD brains compared to age-matched controls. Glucose transport, as well as phosphorylation, appears to be a rate limiting step for glucose metabolism in the brain. We have reviewed the literature on glucose transport abnormalities in AD and the effect such abnormalities have on the brain.MethodPublished literature between 1st January 1946 and 1st November 2019 was identified using EMBASE and MEDLINE databases and titles and abstracts were scanned. Human studies (autopsy and imaging) and data from animal models were included while reviews, letters and cellular or molecular studies were excluded from the search.ResultAutopsy studies in AD patients show significant reductions in GLUT3 in areas of the brain closely associated with AD pathology. Patients with AD and diabetes showed greater reductions of GLUT1 and GLUT3. A longitudinal study showed significant reductions in GLUT3 levels which correlated with greater amyloid-β (Aβ) and neurofibrillary tangle pathological burden in participants with AD pathology at post-mortem but without evidence of cognitive dysfunction in their lifetime. Some studies showed increased GLUT1, with others showing reduced GLUT1, levels in AD brain. A newly recognised GLUT12 appears to be increased in AD. Animal studies showed similar results with GLUT1 and GLUT3 knockout animal models exhibiting AD pathology, while overexpression of GLUT1 or treatment with metformin decreased Aβ toxicity in a Drosophila model of AD. GLUT2 levels were increased in both human AD brain and in an animal model of AD. Imaging studies using fluorodeoxyglucose [18F]FDG with positron emission tomography (FDG-PET) in AD subjects show reductions in glucose transport and glucose metabolism in areas most affected in AD. A small randomised control trial showed anti-diabetic medications improved the glucose transport in AD subjects.ConclusionGLUTs play a significant role in AD pathology with evidence suggesting that GLUT3 reductions may precede the onset of clinical symptoms, while GLUT2 and GLUT12 may have a compensatory role. Repurposing anti-diabetic drugs shows promising results in both animal and human studies of AD.

The relationship of glucose-stimulated insulin secretion to cerebral glucose metabolism and cognition in healthy middle-aged and older adults

Insulin resistance (IR) has been related to reduced cerebral glucose metabolism in regions identified as hypometabolic in Alzheimer's clinical syndrome. Insulin secretion (IS) has been less studied than IR despite findings that decreased IS is an early indicator of future type 2 diabetes and a potential predictor of Alzheimer's clinical syndrome. We investigated whether higher IR and lower IS would be associated with greater age-related reductions in regional cerebral glucose metabolism and worse cognitive performance. Two-hour oral glucose tolerance testing and 18F-fluorodeoxyglucose positron emission tomography were performed on 1–2 occasions on a sample of healthy middle-aged and older adults from the Wisconsin Alzheimer's Disease Research Center. Neuropsychological tests were completed during Alzheimer's Disease Research Center Clinical Core visits. Pattern of findings suggested that lower (not higher) IS was related to higher regional cerebral glucose metabolism in middle aged but not older adults, and lower (not higher) IS was also related to better immediate recall. In the context of healthy insulin sensitivity, lower IS may be beneficial to brain health.

Transcriptome and MiRNAomics Analyses Identify Genes Associated with Cytoplasmic Male Sterility in Cotton (Gossypium hirsutum L.).

Cytoplasmic male sterility (CMS) is important for large-scale hybrid seed production. Rearrangements in the mitochondrial DNA (mtDNA) for the cotton (Gossypium hirsutum L.) CMS line J4A were responsible for pollen abortion. However, the expression patterns of nuclear genes associated with pollen abortion and the molecular basis of CMS for J4A are unknown, and were the objectives of this study by comparing J4A with the J4B maintainer line. Cytological evaluation of J4A anthers showed that microspore abortion occurs during meiosis preventing pollen development. Changes in enzyme activity of mitochondrial respiratory chain complex IV and mitochondrial respiratory chain complex V and the content of ribosomal protein and ATP during anther abortion were observed for J4A suggesting insufficient synthesis of ATP hindered pollen production. Additionally, levels of sucrose, starch, soluble sugar, and fructose were significantly altered in J4A during the meiosis stage, suggesting reduced sugar metabolism contributed to sterility. Transcriptome and miRNAomics analyses identified 4461 differentially expressed mRNAs (DEGs) and 26 differentially expressed microRNAs (DEMIs). Pathway enrichment analysis indicated that the DEMIs were associated with starch and sugar metabolism. Six deduced target gene regulatory pairs that may participate in CMS were identified, ghi-MIR7484-10/mitogen-activated protein kinase kinase 6 (MAPKK6), ghi-undef-156/agamous-like MADS-box protein AGL19 (AGL19), ghi-MIR171-1-22/SNF1-related protein kinase regulatory subunit gamma-1 and protein trichome birefringence-like 38, and ghi-MIR156-(8/36)/WRKY transcription factor 28 (WRKY28). Overall, a putative CMS mechanism involving mitochondrial dysfunction, the ghi-MIR7484-10/MAPKK6 network, and reduced glucose metabolism was suggested, and ghi-MIR7484-10/MAPKK6 may be related to abnormal microspore meiosis and induction of excessive sucrose accumulation in anthers.

Cross-sectional investigation of insulin resistance in youths with autism spectrum disorder. Any role for reduced brain glucose metabolism?

The autism spectrum disorder (ASD) is an etiologically heterogeneous disorder. Dysfunctions of the intermediate metabolism have been described in some patients. We speculate these metabolic abnormalities are associated with brain insulin resistance (IR), i.e., the reduced glucose metabolism at the level of the nervous central system. The Homeostasis model assessment of insulin resistance (HOMA-IR) is very often used in population studies as estimate of peripheral IR and it has been recently recognized as proxy of brain IR. We investigated HOMA-IR in 60 ASD patients aged 4–18 years and 240 healthy controls, also aged 4–18 years, but unmatched for age, sex, body weight, or body mass index (BMI). At multivariable linear regression model, the HOMA-IR was 0.31 unit higher in ASD individuals than in controls, after having adjusted for sex, age, BMI z-score category, and lipids that are factors known to influence HOMA-IR. Findings of this preliminary study suggest it is worth investigating brain glucose metabolism in larger population of patients with ASD by using gold standard technique. The recognition of a reduced glucose metabolism in some areas of the brain as marker of autism might have tremendous impact on our understanding of the pathogenic mechanisms of the disease and in terms of public health.

Altered glucose metabolism of the olfactory-related cortices in anosmia patients with traumatic brain injury.

Impaired brain cortices contribute significantly to the pathophysiological mechanisms of post-traumatic olfactory dysfunction (PTOD). This study aimed to use 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) to measure cerebral cortices' metabolism activity and then to explore their associations with olfaction in patients with PTOD. Ethics committee-approved prospective studies included 15 patients with post-traumatic anosmia and 11 healthy volunteers. Olfactory function was assessed using the Sniffin' Sticks. Participants underwent 18F-FDG PET/CT scan and the image data were collected for the voxel-based whole brain analysis. Furthermore, the standardized uptake value ratio (SUVR) of the whole brain regions was measured and correlated with olfactory function. Patients with post-traumatic anosmia showed significantly reduced glucose metabolism in bilateral rectus, bilateral superior and medial orbitofrontal cortex (OFC), bilateral thalamus, left hippocampus and parahippocampus and left superior temporal pole (all p < 0.001). In contrast, patients with post-traumatic anosmia had significantly increased glucose metabolism in the bilateral insula (all p < 0.001). SUVR values among a total of 17 cerebral cortices including frontal, limbic, and temporal regions were significantly and positively correlated with olfactory function. The cerebral cortices with the top three correlations were the right middle frontal OFC (r = 0.765, p = 0.001), right caudate (r = 0.652, p = 0.010) and right putamen (r = 0.623, p = 0.002). Patients with post-traumatic anosmia presented with distinct patterns of brain metabolism and key cortices that highly associated with the retained olfactory function were identified. The preliminary results further support the potential use of PET imaging for precisely assessing brain metabolism in patients with PTOD.

Evaluating the association between brain atrophy, hypometabolism, and cognitive decline in Alzheimer's disease: a PET/MRI study.

Glucose metabolism reduction and brain volume losses are widely reported in Alzheimer’s disease (AD). Considering that neuroimaging changes in the hippocampus and default mode network (DMN) are promising important candidate biomarkers and have been included in the research criteria for the diagnosis of AD, it is hypothesized that atrophy and metabolic changes of the abovementioned regions could be evaluated concurrently to fully explore the neural mechanisms underlying cognitive impairment in AD. Twenty-three AD patients and Twenty-four age-, sex- and education level-matched normal controls underwent a clinical interview, a detailed neuropsychological assessment and a simultaneous 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET)/high-resolution T1-weighted magnetic resonance imaging (MRI) scan on a hybrid GE SIGNA PET/MR scanner. Brain volume and glucose metabolism were examined in patients and controls to reveal group differences. Multiple linear regression models were employed to explore the relationship between multiple imaging features and cognitive performance in AD. The AD group had significantly reduced volume in the hippocampus and DMN regions (P < 0.001) relative to that of normal controls determined by using ROI analysis. Compared to normal controls, significantly decreased metabolism in the DMN (P < 0.001) was also found in AD patients, which still survived after controlling for gray matter atrophy (P < 0.001). These findings from ROI analysis were further confirmed by whole-brain confirmatory analysis (P < 0.001, FWE-corrected). Finally, multiple linear regression results showed that impairment of multiple cognitive tasks was significantly correlated with the combination of DMN hypometabolism and atrophy in the hippocampus and DMN regions. This study demonstrated that combining functional and structural features can better explain the cognitive decline of AD patients than unimodal FDG or brain volume changes alone. These findings may have important implications for understanding the neural mechanisms of cognitive decline in AD.

Diethyldithiocarbamate-copper complex (CuET) inhibits colorectal cancer progression via miR-16-5p and 15b-5p/ALDH1A3/PKM2 axis-mediated aerobic glycolysis pathway

Exploring novel anticancer drugs to optimize the efficacy may provide a benefit for the treatment of colorectal cancer (CRC). Disulfiram (DSF), as an antialcoholism drug, is metabolized into diethyldithiocarbamate-copper complex (CuET) in vivo, which has been reported to exert the anticancer effects on various tumors in preclinical studies. However, little is known about whether CuET plays an anti-cancer role in CRC. In this study, we found that CuET had a marked effect on suppressing CRC progression both in vitro and in vivo by reducing glucose metabolism. Mechanistically, using RNA-seq analysis, we identified ALDH1A3 as a target gene of CuET, which promoted cell viability and the capacity of clonal formation and inhibited apoptosis in CRC cells. MicroRNA (miR)-16-5p and 15b-5p were shown to synergistically regulate ALDH1A3, which was negatively correlated with both of them and inversely correlated with the survival of CRC patients. Notably, using co-immunoprecipitation followed with mass spectrometry assays, we identified PKM2 as a direct downstream effector of ALDH1A3 that stabilized PKM2 by reducing ubiquitination. Taken together, we disclose that CuET treatment plays an active role in inhibiting CRC progression via miR-16-5p and 15b-5p/ALDH1A3/PKM2 axis–mediated aerobic glycolysis pathway.

Cerebral Microbleeds in Patients with Parkinson's Disease and Dementia with Lewy Bodies: Comparison Using Magnetic Resonance Imaging and 99mTc-ECD SPECT Subtraction Imaging.

Cerebral microbleeds (CMBs) in patients with Parkinson's disease (PD) or dementia with Lewy bodies (DLB) have not been adequately studied. This study aims to find a difference in the total number, prevalence, and common locations of CMBs between PD and DLB and evaluate 99mTc-ECD SPECT subtraction images of these two diseases. We examined 112 patients with PD (53 males and 59 females; age: 77.4±3.6 years) and 28 age-matched patients with DLB (15 males and 13 females; age: 77.1±6.7 years) using brain magnetic resonance imaging (MRI) and 99mTc-ECD SPECT subtraction imaging. The total number of CMBs was higher in patients with DLB (41.2%) than in those with PD (11.5%), and the prevalence was significantly higher in the former (0.7±1.1) than the latter (0.2±0.5, p < 0.05). The odds ratio was 5.4 (95% confidence interval [CI]: 1.7-17.4). Furthermore, CMBs were commonly located in the basal ganglia of patients with PD (6 out of 87 patients) but in the occipital lobe of patients with DLB (8 out of 17 patients). 99mTc-ECD SPECT subtraction imaging indicated lower cerebral blood flow in the posterior cingulate gyrus among the patients with CMB-positive DLB than among those with CMB-positive PD; additionally, the cerebral blood flow was lower in the bilateral basal ganglia and midbrain among patients with CMB-positive DLB compared to those with CMB-negative DLB. A reduction in occipital glucose metabolism may be related to CMBs in the occipital lobe of patients with DLB.

Anosognosia in Alzheimer’s disease associated with tau accumulation and hypometabolism in frontal areas

AbstractBackgroundImpaired insight in cognitive deficits (anosognosia) in Alzheimer’s disease (AD) is frequent and problematic, but pathophysiological mechanisms are not fully understood. So far, several regions such as the cingulate cortex or frontotemporal regions have been identified as crucial. The aim of the present study was to explore the neural substrates of anosognosia in AD by applying 18‐F fluorodeoxyglucose (FDG) and 18‐F‐AV‐1451 (Tau) positron emission tomography (PET).MethodSeventy‐four AD‐patients with mild cognitive impairment (MCI) or dementia were included in this study. Anosognosia was assessed by a clinician, based on a structured interview compared to patient’s subjective cognitive impairment. Cognition was examined applying the Consortium to Establish a Registry for AD (CERAD‐Plus) neuropsychological assessment battery. All patients underwent FDG‐PET. Additionally, 29 patients received a Tau‐PET. Glucose metabolism and 18‐F‐AV‐1451 binding were analyzed in a whole brain approach by comparing patients with and without anosognosia. Imaging analyses were controlled for age and sex.ResultOf the 74 patients, 28 had anosognosia and 46 were aware of their deficits. Patients with anosognosia were significantly older and less depressed. The number of MCI/dementia patients was similar between groups (MCI+/‐anosognosia 11/25, dementia +/‐anosognosia 17/21, p=.209). Neuropsychological results showed a significantly more impaired verbal fluency in patients with anosognosia (p=.025). When FDG‐PET images were analyzed, patients with anosognosia had a significantly lower glucose metabolism in the inferior frontal gyrus, rectal gyrus and medial frontal gyrus including the anterior cingulate cortex (cluster level, p‐uncorrected&lt;0.001, FWE‐corrected p=.006). Tau‐PET analyses showed a significant higher tracer binding in patients with anosognosia in the inferior and medial frontal gyrus (cluster level, p‐uncorrected=.003, FWE‐corrected p=.048).ConclusionThis is the first study examining FDG‐ and Tau‐PET in AD patients with and without anosognosia. Anosognosia was not only associated with reduced glucose metabolism but also with increased tau accumulation in inferior and medial frontal regions. We speculate that tau‐induced hypometabolism in regions related to self‐referential processes leads to anosognosia.

Mild behavioral impairment associates with Alzheimer’s disease biomarkers and greater risk of incident dementia in patients with MCI

AbstractBackgroundMild behavioral impairment (MBI) is characterized by later life onset of sustained neuropsychiatric symptoms (NPS) as an at‐risk state for incident cognitive decline and dementia. Here we assess differences in sustained NPS versus transient NPS versus no NPS, on neuroimaging markers and cognitive scores, and the risk of progression to dementia.MethodData from 764 individuals with MCI from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) were analyzed. NPI‐Q items were transformed to MBI domains using a published algorithm. MBI requires sustained NPS for 6 months, thus we grouped individuals based on two visits 6‐months apart as sustained (present at both visits, n=258), transient (present at one visit, n=346), and no NPS (present at neither visit, n=160). For the cross‐sectional analyses, outcomes of interest were matched to the clinical visits assessing NPS. We investigated differences in brain metabolic activity by [18F] fluorodeoxyglucose (FDG)‐PET, and composite scores of executive functioning and memory in these groups using multiple linear regression adjusted for age, sex and education. Time‐varying cox regression models were constructed, adjusting for age, sex, and education to assess if time to dementia is associated with MBI.ResultIn these participants with MCI, compared to individuals with no NPS, sustained NPS was associated with reduced [18F] FDG uptake [Adjusted‐=‐0.06 (SE=0.02); p value=0.003], lower executive functioning scores [Adjusted‐=‐0.28 (SE=0.08); p value=0.001], and memory impairment [Adjusted‐=‐0.38 (SE=0.08); p value=&lt;.001]. Compared to individuals with transient NPS, sustained NPS was also associated with reduced glucose metabolism [Adjusted‐=‐0.03 (SE=0.01); p value=0.018], and lower memory scores [Adjusted‐=‐0.17 (SE=0.06); p value=0.007], but not executive functioning. Compared to no or transient NPS, the risk for incident dementia was highest in the sustained NPS group (HR 1.87, 95% CI 1.50 to 2.34).ConclusionIn a cohort of individuals with MCI, baseline NPS are associated with biomarkers of dementia risk and predict progression to dementia. MBI, as operationalized here by sustained NPS, was associated with worse memory, lower glucose metabolism, and higher risk of incident dementia compared to transient NPS. There is diagnostic and prognostic utility in determining if NPS are sustained or transient, further validating the MBI construct.

Aberrant protein O‐GlcNAcylation drives AD‐like neurodegeneration in DS mice

AbstractBackgroundDown syndrome (DS) is related with an increased incidence of Alzheimer’s disease (AD) neuropathology. Among the putative mechanisms leading neurodegeneration, the reduction of cerebral glucose metabolism may trigger brain damage by impacting the hexosamine biosynthetic pathway (HBP). As reported in AD, defective HBP is responsible for flawed protein O‐GlcNAcylation coupled by a mutual inverse increase of protein phosphorylation on Ser/Thr residues, which gives to O‐GlcNAcylation the ability to modulate various pathways involved in AD progression. Previous studies have shown the aberrant O‐GlcNAcylation/phosphorylation ratio of tau and APP in AD brain, confirming dysfunctional O‐GlcNAcylation as a key contributor in the pathogenesis of the disease. Our work aims to unravel, for the first time, the role of protein O‐GlcNAcylation in DS neuropathology along with its possible pharmacological modulation to prevent DS cognitive decline.MethodsWe performed western blot analysis of global O‐GlcNAc levels and total protein Ser/Thr phosphorylation in the hippocampus of 6‐months‐old Ts2Cje, mouse model of DS, compared to age‐matched controls. Furthermore, we measured the activity of enzymes involved in O‐GlcNAcylation cycling (OGT and OGA), as well as the functionality of GFAT1, the rate limiting enzyme of the HBP. Additionally, we determined by immunoprecitation the O‐GlcNAcylation/phosphorylation ratio of AD‐related markers (tau and APP). Finally, we tested the efficacy of an intranasal short‐term treatment with an O‐GlcNAc‐modulating compound.ResultsWe observed an early reduction of total O‐GlcNAcylation levels in young Ts2Cje mice and established its correlation with an increase in total protein phosphorylation. We measured the alteration in OGT and OGA functionality, unrelated with a dysfunctional activity of GFAT1. Moreover, we demonstrated that the reduction of O‐GlcNAcylation/phosphorylation levels affects both tau and APP, actively contributing to DS neuropathology. Lastly, our novel therapeutic strategy was able to increase O‐GlcNAc levels in Ts2Cje mice and restore AD‐related markers, possibly slowing disease progression.ConclusionOur research highlights the pathological role of the altered protein O‐GlcNAcylation profile in DS neurodegeneration and investigates the neuroprotective effects of an O‐GlcNAc‐modulating compound.

The Differential Influence of Immune, Endocytotic, and Lipid Metabolism Genes on Amyloid Deposition and Neurodegeneration in Subjects at Risk of Alzheimer's Disease.

Over 20 single-nucleotide polymorphisms (SNPs) are associated with increased risk of Alzheimer's disease (AD). We categorized these loci into immunity, lipid metabolism, and endocytosis pathways, and associated the polygenic risk scores (PRS) calculated, with AD biomarkers in mild cognitive impairment (MCI) subjects. The aim of this study was to identify associations between pathway-specific PRS and AD biomarkers in patients with MCI and healthy controls. AD biomarkers ([18F]Florbetapir-PET SUVR, FDG-PET SUVR, hippocampal volume, CSF tau and amyloid-β levels) and neurocognitive tests scores were obtained in 258 healthy controls and 451 MCI subjects from the ADNI dataset at baseline and at 24-month follow up. Pathway-related (immunity, lipid metabolism, and endocytosis) and total polygenic risk scores were calculated from 20 SNPs. Multiple linear regression analysis was used to test predictive value of the polygenic risk scores over longitudinal biomarker and cognitive changes. Higher immune risk score was associated with worse cognitive measures and reduced glucose metabolism. Higher lipid risk score was associated with increased amyloid deposition and cortical hypometabolism. Total, immune, and lipid scores were associated with significant changes in cognitive measures, amyloid deposition, and brain metabolism. Polygenic risk scores highlights the influence of specific genes on amyloid-dependent and independent pathways; and these pathways could be differentially influenced by lipid and immune scores respectively.