Hyon-Ah Yi

Visceral adipose tissue (VAT) dysfunction has been recently recognized as a potential contributor to the development of Alzheimer’s disease (AD). This study aimed to explore the relationship between VAT metabolism and cerebral glucose metabolism in patients with cognitive impairment. This cross-sectional prospective study included 54 patients who underwent ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) brain and torso positron emission tomography/computed tomography (PET/CT), and neuropsychological evaluations. VAT metabolism was measured by ¹⁸F-FDG torso PET/CT, and cerebral glucose metabolism was measured using ¹⁸F-FDG brain PET/CT. A voxel-based analysis revealed that the high-VAT-metabolism group exhibited a significantly lower cerebral glucose metabolism in AD-signature regions such as the parietal and temporal cortices. In the volume-of-interest analysis, multiple linear regression analyses with adjustment for age, sex, and white matter hyperintensity volume revealed that VAT metabolism was negatively associated with cerebral glucose metabolism in AD-signature regions. In addition, higher VAT metabolism was correlated with poorer outcomes on cognitive assessments, including the Korean Boston Naming Test, Rey Complex Figure Test immediate recall, and the Controlled Oral Word Association Test. In conclusion, our study revealed significant relationships among VAT metabolism, cerebral glucose metabolism, and cognitive function. This suggests that VAT dysfunction actively contributes to the neurodegenerative processes characteristic of AD, making VAT dysfunction targeting a novel AD therapy approach.

Background: Diabetes mellitus (DM) increases the risk of brain atrophy and dementia. We aimed to reveal whether DM could affect cognitive function and the pattern of amyloid retention in cognitively impaired patients. Also we tried to show whether the existence of DM could cause subcortical structural abnormalities with cognitive dysfunction.Method: We included consecutive 56 controls and 145 cognitively impaired people (CI, 50 MCI and 95 mild to moderate Alzheimer’s disease (AD) patients). All participants of this cross‐sectional study underwent blood tests, detailed neuropsychological evaluations, 3D T1‐weighted MRI at 3‐Tesla and ¹⁸F‐FBB‐PET. We estimated the cerebral Aβ burden quantitatively using volume‐of‐interest analysis and segmented the volumes of six subcortical structures, using FMRIBs integrated registration and segmentation tool Multiple linear regression analysis adjusted for age and gender was performed to evaluate the relationship among cerebral Aβ burden, cognitive function and diabetes.Result: All subcortical structures, except for the globus pallidus, were smaller in CI compared with controls on adjusting for age and gender. CI with DM was associated with the lower volumes of caudate nucleus and putamen than CI without DM patients. Although there was no significant difference of MMSE score within two groups, the performance of frontal‐executive and memory functions was negatively correlated with subcortical structural volume loss in CI with DM. There was no difference between cerebral Aβ burden using composite SUVR and MMSE score in CI patients. However we found higher amyloid retention in CI with DM patients.Conclusion: The co‐morbidity of DM in AD patients might cause more specific subcortical volume loss beyond diffuse cerebral atrophy and the resultant cortical‐subcortical dysfunction could make cognitive dysfunction worse, especially frontal‐executive and memory functions. Also, CI with DM patients showed higher cerebral amyloid retention, which might be the accelerating factor of cognitive deterioration.

The visceral adipose tissue (VAT) has been recognized as an endocrine organ, and VAT dysfunction could be a risk factor for Alzheimer’s disease (AD). We aimed to evaluate the association of VAT metabolism with AD pathology. This cross-sectional study included 54 older subjects with cognitive impairment who underwent 2-deoxy-2-[fluorine-18]-fluoro-D-glucose (¹⁸F-FDG) torso positron emission tomography (PET) and ¹⁸F-florbetaben brain PET. ¹⁸F-FDG uptake in VAT on ¹⁸F-FDG PET images was used as a marker of VAT metabolism, and subjects were classified into high and low VAT metabolism groups. A voxel-based analysis revealed that the high VAT metabolism group exhibited a significantly higher cerebral amyloid-β (Aβ) burden than the low VAT metabolism group. In the volume-of-interest analysis, multiple linear regression analyses with adjustment for age, sex, and white matter hyperintensity volume revealed that ¹⁸F-FDG uptake in VAT was significantly associated with the cerebral Aβ burden (β = 0.359, p = 0.007). In conclusion, VAT metabolism was associated with AD pathology in older subjects. Our findings suggest that VAT dysfunction could contribute to AD development.

The outbreak of the COVID-19 pandemic is a substantial threat to the health of all populations worldwide, and old age is a robust risk factor for poor prognosis of COVID-19 infection. To reduce the fatality rate of COVID-19 infection, further understanding of elderly patients with COVID-19 is necessary. We aimed to investigate the prognostic factors in elderly patients with COVID-19. This was a multicenter and retrospective study. Overall, 340 elderly patients with COVID-19 were enrolled in 3 hospitals in Daegu, South Korea. Death and severe pneumonia requiring oxygen treatment were defined as poor clinical outcomes. Of the patients studied, 15% died and 35.2% were classified as having severe pneumonia. In binary logistic regression analysis, activities of daily living (ADL) impairment, fever during hospitalization, initial infiltration on chest radiograph, and initial increased C-reactive protein (CRP) were significantly associated with severe pneumonia (OR = 5.33, p < 0.001; OR = 3.2, p = 0.002; OR = 2.32, p = 0.044; and OR = 1.33, p < 0.001, respectively). ADL impairment, comorbidity, fever during hospitalization, and initial increased CRP were significantly associated with death (OR = 7.13, p < 0.001; OR = 3.28, p = 0.005; OR = 3.15, p = 0.032, and OR = 1.18, p < 0.001, respectively). ADL impairment, fever, and initial CRP were poor prognostic factors in elderly patients with COVID-19. Understanding these poor prognostic factors is necessary to control the disease in elderly patients.

Background: Although several studies have reported an association between thyroid dysfunction and Alzheimer's disease (AD), the effect of mild thyroid dysfunction within the normal range of thyrotropin (TSH) on the development of AD remains unclear. The aim of this study was to evaluate the association between thyroid hormones and the pathology of AD in euthyroid subjects. Methods: Sixty-nine subjects with a TSH level between 0.5 and 4.5 μIU/L who underwent ¹⁸ F-florbetaben positron emission tomography were included in this prospective cross-sectional study. The levels of serum free thyroxine (fT4) and TSH were quantified using radioimmunoassay. Neuropsychological tests were performed to assess cognitive function. Differences in cerebral amyloid-β (Aβ) burden were compared between high-normal TSH (TSH ≥2.5 μIU/mL) and low-normal TSH (TSH p = 0.009). The fT4 levels were negatively correlated with cerebral Aβ burden ( β = −0.240, p = 0.035), and TSH levels were positively correlated with cerebral Aβ burden ( β = 0.267, p = 0.020). The fT4 level was also positively associated with cognitive function, as inferred from neuropsychological test scores. Conclusions: Thyroid hormone concentrations were associated with AD pathology in euthyroid subjects. Our findings suggest that AD is likely to occur even in individuals with high-normal TSH levels.

The relationship between postural instability and subcortical structure in AD has received less attention. The aims of this study were to assess whether there are differences in the ability to control balance between Alzheimer's disease (AD) and controls, and to investigate the association between subcortical gray matter volumes and postural instability in AD. We enrolled 107 consecutive AD patients and 37 controls. All participants underwent detailed neuropsychological evaluations, T1-weighted MRI at 3 T, and posture assessment using computerized dynamic posturography. We segmented the volumes of 6 subcortical structures of the amygdala, thalamus, caudate nucleus, putamen, globus pallidus and nucleus accumbens, and of hippocampus, using the FMRIBs integrated registration and segmentation tool. All subcortical structures, except for the globus pallidus, were smaller in AD compared with controls on adjusting for age and gender. Falling frequencies in unilateral stance test (UST) and composite scores in sensory organization test (SOT) were worse in AD than in controls. The motor control test did not reveal any differences between groups. On subgroup analyses in AD, the groups with poor performance in UST or SOT exhibited significantly reduced nucleus accumbens and putamen volumes, and nucleus accumbens volume, respectively. The smaller volume of the nucleus accumbens was associated with postural instability in AD (OR [95% CI] 17.847 [2.59–122.80] for UST, 42.827[6.06–302.47] for SOT, all P < .05). AD patients exhibited reduced ability to control balance compared with controls, and this postural instability was associated with nucleus accumbens volume loss. Furthermore, cognitive dysfunction was more prominent in the group with severe postural instability.