BACKGROUND: Although studies and interest in sarcopenia have increased, it is still a matter of debate which muscle mass index better represents the aging process. We compared 3 indices for muscle mass (appendicular skeletal muscle mass [ASM]/weight, ASM/height2, and the body mass index [BMI]-adjusted muscle mass index [ASM/BMI]) to determine which better reflected the aging process in terms of the decline in bone mineral density (BMD), visual acuity (VA), hearing power, renal function, pulmonary function, and handgrip strength. METHODS: We performed a retrospective cross-sectional study using the Korea National Health and Nutrition Examination Survey in the Korean population. Between 2008 and 2011, a total of 14,415 men and 17,971 women aged 10 years or older participated in the study. We plotted the changes in the 3 indices of muscle mass and compared these with changes in BMD, VA, hearing power, renal function, pulmonary function, and handgrip strength according to each age group. RESULTS: The ASM/BMI showed similar changes in terms of surrogate markers of the aging process, while the ASM/weight and ASM/height2 showed no correlation. CONCLUSIONS: Among muscle indices for sarcopenia, only the ASM/BMI represented the aging process.
Aging* ; Biomarkers ; Body Mass Index ; Bone Density ; Cross-Sectional Studies ; Female ; Hearing ; Humans ; Korea ; Male ; Muscle, Skeletal ; Nutrition Surveys ; Retrospective Studies ; Sarcopenia ; Visual Acuity

Objective:To explore the value of the amyloid-tau-neurodegeneration (ATN) framework in neuroimaging based on PET for diagnosing mild cognitive impairment (MCI) and Alzheimer′s disease (AD), and analyze its relationship with clinical cognition.Methods:From May 2022 to March 2024, a total of 98 cases (23 males and 75 females, age (67.8±8.6) years) with a diagnosis of AD, MCI, or non-AD (control patients, CP) who underwent 18F-FDG, 18F-AV45, and 18F-AV1451 PET/CT imaging in the Second Affiliated Hospital of Guangzhou Medical University were included retrospectively. The clinical data, Mini-Mental State Examination (MMSE), and Montreal Cognitive Assessment (MoCA) scores were recorded. Cases were divided into MCI group, mild AD group, moderate AD group, moderate-severe AD group, and CP group. PET images were visually and semi-quantitatively evaluated. SUV mean and SUV ratio (SUVR) were obtained from independent brain regions of 18F-FDG ( n=8), 18F-AV45 ( n=14) and 18F-AV1451 ( n=14). ROC curve analysis was performed with clinical diagnosis as a criterion. The consistency between visual assessment and the clinical diagnosis was analyzed by Cohen′s Kappa coefficient. Semi-quantitative comparisons between groups were performed using the independent-sample t test, one-way analysis of variance, Mann-Whitney U test, or Kruskal-Wallis rank sum test. Age was used as a covariate to calculate the partial correlation coefficient between SUVR and cognitive scores. Results:The sensitivity and specificity of comprehensive visual assessment in diagnosing AD+ MCI were 87.65%(71/81) and 14/17 respectively, showing a moderate consistency with clinical diagnosis ( Kappa=0.60, P<0.001). Semi-quantitative analysis showed that 18F-FDG uptakes in all independent brain regions of MCI patients were higher than those of AD patients, whereas the uptakes of 18F-AV45 and 18F-AV1451 were lower ( t values: 2.66-3.95, z values: 4.98-15.04, all P<0.05). The difference in 18F-AV45 uptake among the three subgroups of AD was relatively small ( H values: 0.46-4.06, F values: 0.03-0.08, all P>0.05). Except for the medial temporal and occipital lobes, the 18F-AV1451 uptake in the moderate-severe AD group tended to be higher than that in the moderate and mild AD groups, though not statistically significant ( H values: 0.20-5.17, all P>0.05). 18F-FDG PET semi-quantitatively distinguished MCI from CP with a high sensitivity (13/14), 18F-AV45 demonstrated a high sensitivity for diagnosing AD+ MCI (92.59%, 75/81), and 18F-AV1451 had a high specificity for distinguishing AD from MCI (14/14) (AUCs: 0.87, 0.90 and 0.92). The uptakes of 18F-FDG in gray matter of AD and MCI patients were positively correlated with MMSE and MoCA scores ( r values: 0.30-0.43, 0.29-0.45, all P<0.05), while the uptakes of 18F-AV45 and 18F-AV1451 were negatively correlated with MMSE and MoCA scores ( 18F-AV45, r values: from -0.39 to -0.30, from -0.38 to -0.30, all P<0.05; 18F-AV1451, r values: from -0.50 to -0.28, from -0.53 to -0.28, except for medial temporal lobe P>0.05, all others P<0.05). Conclusion:The PET-based neuroimaging ATN framework is helpful for early diagnosis of MCI and AD, as well as for AD staging, and may reflect the disease progression and clinical cognitive status of AD to a certain extent.