Non-Alzheimer types of neurodegenerative dementia: clinical and 18F-FDG-PET/CT pictures

Glucose Metabolism Impairment in Parkinson's Disease

Impairments in systematic and regional glucose metabolism exist in patients with Parkinson's disease (PD) at every stage of the disease course, and such impairments are associated with the incidence, progression, and special phenotypes of PD, which affect each physiological process of glucose metabolism including glucose uptake, glycolysis, tricarboxylic acid cycle, oxidative phosphorylation, and pentose phosphate shunt pathway. These impairments may be attributed to various mechanisms, such as insulin resistance, oxidative stress, abnormal glycated modification, blood-brain-barrier dysfunction, and hyperglycemia-induced damages. These mechanisms could subsequently cause excessive methylglyoxal and reactive oxygen species production, neuroinflammation, abnormal aggregation of protein, mitochondrial dysfunction, and decreased dopamine, and finally result in energy supply insufficiency, neurotransmitter dysregulation, aggregation and phosphorylation of α-synuclein, and dopaminergic neuron loss. This review discusses the glucose metabolism impairment in PD and its pathophysiological mechanisms, and briefly summarized the currently-available therapies targeting glucose metabolism impairment in PD, including glucagon-likepeptide-1 (GLP-1) receptor agonists and dual GLP-1/gastric inhibitory peptide receptor agonists, metformin, and thiazoledinediones.

Exploring the Relationship Between Deficits in Social Cognition and Neurodegenerative Dementia: A Systematic Review

Background

Neurodegenerative diseases might affect social cognition in various ways depending on their components (theory of mind, emotional processing, attribution bias, and social perception) and the subtype of dementia they cause. This review aims to explore this difference in cognitive function among individuals with different aetiologies of dementia.

Methods

The following databases were explored: MEDLINE via PubMed, Cochrane Library, Lilacs, Web of Science, and PsycINFO. We selected studies examining social cognition in individuals with neurodegenerative diseases in which dementia was the primary symptom that was studied. The neurodegenerative diseases included Alzheimer's disease, Lewy body disease and frontotemporal lobar degeneration. The search yielded 2,803 articles.

Results

One hundred twenty-two articles were included in the present review. The summarised results indicate that people with neurodegenerative diseases indeed have deficits in social cognitive performance. Both in populations with Alzheimer's disease and in populations with frontotemporal dementia, we found that emotional processing was strongly affected. However, although theory of mind impairment could also be observed in the initial stages of frontotemporal dementia, in Alzheimer's disease it was only appreciated when performing highly complex task or in advanced stages of the disease.

Conclusions

Each type of dementia has a differential profile of social cognition deterioration. This review could provide a useful reference for clinicians to improve detection and diagnosis, which would undoubtedly guarantee better interventions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020152562, PROSPERO, identifier: CRD42020152562.

The mechanism of lipopolysaccharide administration-induced cognitive function impairment caused by glucose metabolism disorder in adult rats

This essay aims to make investigation on the mechanism of glucose metabolism disorder and Lipopolysaccharide administration-induced cognitive function impairment in adult rats with surgery. Methods: Divide the objects, 40 male Sprague-Dawley rats at the age of 9 months, into 4 groups. Provide unilateral nephrectomy surgery and/or lipopolysaccharide intraperitoneal injection. Postoperative cognitive function evaluation would be tested by the Morris water maze. Rats with Postoperative Cognitive Dysfunction (POCD) were scanned to analyze the brain glucose metabolism by means of 18F-FDG PET/CT. Phosphatidylinositol 3-Kinase (PI3K), Protein Kinase β (AKT), Insulin Substrates Receptor-2 (IRS-2) and Glucose Transporter 4 (GLUT4) were detected as well. Data will be captured through gene expression in POCD rats via Quantitative Real-Time PCR (QRT-PCR). On the other side, Western Blot was used to measure the expression levels of IRS-2, p-IRS-2, p-PI3K, PI3K, p-AKT, AKT, GLUT4, and p-GLUT4. Results: During the Morris water maze test, the staging time (latency) of rats in each group was becoming short gradually as the training progressed. The incubation time of Day 5 of each group was shorter than that of Day 1 (P < 0.05). On the Day 3 after the surgery, the average target quadrant residence time of Group S+L (100 μg/Kg) was shorter, compared with Group C, L and S. Of which, the average number of perforation was reduced greater than that of Group C (P < 0.05). The average swimming speed of the groups is of no distinct difference (P > 0.05). After the operation, there was no great difference shown among the subjects (P > 0.05) in the average residence time of the target quadrant, the mean number of passages, and the mean swimming speed. On Day 3, the average latency of Group S+L (100 μg/Kg) was longer than Group C (P < 0.05) in the working memory test after the operation. The average latency of rats in Group L and S was showed longer than that in Group C, with tiny difference (P > 0.05). In the 7-Day working memory test, the average latency of the rats in Group L, S and S+L (100 μg/Kg) was obviously longer than that in Group C. Comparing to preoperative rats, POCD rats of Group S+L (100 μg/Kg) were scanned by 18F-FDG PET/CT three days later after the operation. Its SUVmax of the frontal and temporal lobe areas were decreased significantly (P < 0.05). However, difference degree was not significantly shown in the SUVmax between Group C and the preoperative rats (P > 0.05). In comparison with the gene expression of of Group C, the PI3K, IRS-2, AKT and GLUT4 mRNA genes are the key genes in the insulin signaling pathways of the hippocampus of the POCD rats. The expression level was reduced. The expression level of all protein of PI3K, IRS-2, GLUT4 and AKT in the POCD rats was of no great contrast with that in Group C. But for IRS-2 protein, the phosphorylation level has increased, and meanwhile decreased for AKT, PI3K and GLUT4 proteins (P < 0.05). Conclusions: Adult SD rats cognitive dysfunction model treated with unilateral nephrectomy combined and 100 μg/kg LPS intraperitoneal injection were led to abnormal both brain glucose metabolism and insulin expression. The proved phenomenal results signal pathway-related proteins PI3K, IRS-2, AKT and GLUT4. It reached the conclusion that surgical trauma, rather than anesthesia, leads to impaired cognitive function. PI3K, IRS-2, AKT, and GLUT4pathway of brain can be partial explanations of the pathogenesis of POCD.

Construction of a novel Chinese normal brain database using 18F-FDG PET images and MIMneuro software, the initial application in epilepsy

PURPOSE

To create a standard Western Chinese normal functional brain database for quantitative analysis using 2-deoxy-2-[18F] fluoro-d-glucose (¹⁸F-FDG) positron emission tomography (PET) images and MIMneuro software.

METHODS

78 healthy right-handed Chinese volunteers from Tangdu Hospital were scanned using ¹⁸F-FDG PET to evaluate brain metabolism between March and October 2016. All PET images were processed using MIMneuro software to create a normal database platform. The platform included anatomical optimization to facilitate spatial localization of abnormalities and a statistical comparison with normal cases utilizing the Z-scores, which represent the number of standard deviations from the mean of the normal controls in the database.

RESULTS

The novel Chinese brain metabolism database platform including 78 healthy volunteers (male: female 40:38; age 3-78 years, mean age, 45 years) was constructed based on the MIMneuro software, which increased the diagnostic confidence in the test patient by quantifying and emphasizing the abnormality. The BrainAlign^TM deformation algorithm of MIMneuro matched the size, shape, and orientation of the patient's brain scan to a template brain for comparison against a database of normal controls. The quantitative analysis performed on a voxel and regional level was useful in assessing the areas of abnormalities.

CONCLUSIONS

A novel Chinese ¹⁸F-FDG PET-based normal brain function database was created to highlight the local regions of abnormal metabolic activity through quantitative comparisons against the normal database. The Z-scores obtained by MIMneuro potentially aid in visualizing and quantifying the subtle lesions on ¹⁸FDG-PET scan images as observed in a patient diagnosed with epilepsy.

Usefulness of 3-dimensional stereotactic surface projection FDG PET images for the diagnosis of dementia

To compare diagnostic performance and confidence of a standard visual reading and combined 3-dimensional stereotactic surface projection (3D-SSP) results to discriminate between Alzheimer disease (AD)/mild cognitive impairment (MCI), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD).[F]fluorodeoxyglucose (FDG) PET brain images were obtained from 120 patients (64 AD/MCI, 38 DLB, and 18 FTD) who were clinically confirmed over 2 years follow-up. Three nuclear medicine physicians performed the diagnosis and rated diagnostic confidence twice; once by standard visual methods, and once by adding of 3D-SSP. Diagnostic performance and confidence were compared between the 2 methods.3D-SSP showed higher sensitivity, specificity, accuracy, positive, and negative predictive values to discriminate different types of dementia compared with the visual method alone, except for AD/MCI specificity and FTD sensitivity. Correction of misdiagnosis after adding 3D-SSP images was greatest for AD/MCI (56%), followed by DLB (13%) and FTD (11%). Diagnostic confidence also increased in DLB (visual: 3.2; 3D-SSP: 4.1; P < 0.001), followed by AD/MCI (visual: 3.1; 3D-SSP: 3.8; P = 0.002) and FTD (visual: 3.5; 3D-SSP: 4.2; P = 0.022). Overall, 154/360 (43%) cases had a corrected misdiagnosis or improved diagnostic confidence for the correct diagnosis.The addition of 3D-SSP images to visual analysis helped to discriminate different types of dementia in FDG PET scans, by correcting misdiagnoses and enhancing diagnostic confidence in the correct diagnosis. Improvement of diagnostic accuracy and confidence by 3D-SSP images might help to determine the cause of dementia and appropriate treatment.

PET imaging in neurology: Alzheimer's and Parkinson's diseases

PET studies play an important role in the early detection of Alzheimer's and Parkinson's diseases (AD and PD). Fluorine-18 fluorodeoxyglucose (F-FDG) PET imaging of regional cerebral glucose metabolism and PET amyloid imaging are the two major PET studies for AD. F-FDG PET is highly sensitive for the early diagnosis of AD, in predicting conversion from mild cognitive impairment to AD, and in differentiating AD from other dementias. PET amyloid imaging is positive in the majority of patients with AD. Negative amyloid PET reduces the likelihood of AD. The main limitations of PET amyloid imaging is its high positivity in the normal elderly population and in other medical conditions with amyloid pathologies. Various PET tracers are available to assess motor and cognitive dysfunctions in PD. PET tracers targeting presynaptic dopaminergic function (F-DOPA, radiolabeled PET tracers assessing the availability of dopamine transporters and vesicular monoamine transporters) and postsynaptic dopamine receptors are used to assess motor dysfunction in PD. PET tracers, particularly dopamine transporters, are highly sensitive in the early diagnosis of PD. Uptake of PET tracers in the striatum is inversely correlated with disease severity. PET is valuable in differentiating PD from other movement disorders. PET studies, particularly F-FDG PET, help to evaluate cortical metabolism in PD patients with cognitive dysfunction and dementia.