Keita Sakurai

BackgroundAlthough neuroimaging differences from Alzheimer's disease (AD) in argyrophilic grain disease (AGD), a limbic-predominant 4-repeat tauopathy, have been evaluated, edge-wise alterations in structural similarity remain unexamined.ObjectiveAs an exploratory pilot study, to apply network-based statistics (NBS) to individualized structural covariance (ISC) matrices to identify morphological-similarity alterations in AGD and AD.MethodsWe analyzed 3D T1-weighted MRI from 13 pathologically confirmed AGD, 17 AD, and 18 healthy controls (HC). Gray-matter volumes from a 170-region atlas were used to compute ISC matrices. Between-group differences were assessed using NBS (threshold t = 3.5; 5000 permutations). Component strength was the sum of ISC edge weights within the significant component. Stability was assessed via leave-one-out analyses and bootstrap confidence intervals. Significant edges were mapped to Yeo 7 resting-state networks.ResultsAll three comparisons yielded a single significant component (HC versus AD: 340 edges; HC versus AGD: 80 edges; AGD versus AD: 39 edges). Component strength was higher in the group with less widespread morphological disruption (HC > AD; HC > AGD; AGD > AD), with non-overlapping bootstrap confidence intervals. Mapping to resting-state networks revealed widespread posterior cortico-limbic involvement in AD and a limbic-predominant pattern in AGD. In the AGD versus AD comparison, AD showed greater disruption within frontoparietal, somatomotor, and ventral attention systems. Component strength correlated positively with Mini-Mental State Examination scores (r = 0.48, p = 0.01).ConclusionsNBS applied to ISC matrices provides preliminary evidence of altered morphological similarity in AGD and AD, with AGD showing a limbic-predominant subnetwork and AD demonstrating broader posterior cortico-limbic involvement.

BACKGROUND: Amyloid-β and tau deposition follow distinct spatial and temporal trajectories across the Alzheimer's disease (AD) continuum. Amyloid accumulation occurs early in the disease course, whereas tau pathology is more closely associated with neurodegeneration and clinical progression. Characterizing stage-specific regional divergence between amyloid and tau deposition may refine biomarker-based disease staging and improve prognostic assessment. METHODS: We analyzed participants from the BATON study who underwent amyloid PET with 18F-flutemetamol, tau PET with 18F-MK-6240, and 3D MRI within a three-month interval. Participants were classified into cognitively normal amyloid-negative controls (CNA, n = 101) and the AD continuum (n = 102), comprising preclinical AD (PCA, n = 47), mild cognitive impairment due to AD (MCA, n = 24), and AD dementia (ADD, n = 31). Standardized uptake value ratios (SUVRs) were calculated using the Centiloid and CenTauR frameworks, and voxel-wise tau-to-amyloid ratio (TAR) images were generated. Voxel-wise and region-of-interest analyses were performed to compare regional patterns of amyloid deposition, tau accumulation, and TAR across disease stages. RESULTS: Amyloid deposition was already widespread at the PCA stage, involving the frontal, posterior cingulate/precuneus, and temporal cortices. In contrast, tau deposition in PCA was largely confined to the medial temporal lobe. With progression to MCA and ADD, tau burden increased substantially and extended to the lateral temporal, parietal, and frontal cortices. TAR analysis demonstrated high values in the medial temporal cortex at the PCA stage, followed by decreasing TAR in frontal regions during MCA and a tau-dominant neocortical pattern in ADD. CONCLUSIONS: Amyloid and tau exhibit distinct and stage-dependent regional dissociation across the AD continuum. TAR imaging effectively captures this divergence, reflecting early medial temporal tau predominance and subsequent neocortical tau expansion. These findings support the utility of integrated amyloid-tau PET metrics for refined disease staging and longitudinal therapeutic monitoring.

INTRODUCTION: This study aimed to evaluate the usefulness of the fox finger and reverse fox finger imitation tasks as screening tools for detecting cognitive impairment, including mild cognitive impairment (MCI) and dementia. METHODS: A total of 132 older adults visiting a memory clinic were classified into four groups: cognitively normal (CN; n=16), MCI (n=43), Alzheimer's dementia (n=60), and non-Alzheimer's dementia (n=13). Participants completed both imitation tasks, and performance was compared across groups. Sensitivity and specificity were calculated, and voxel-based morphometry (VBM) was used to identify brain atrophy associated with task performance. RESULTS: The fox finger task was successfully completed by 77.5% of participants, with significantly higher success in the CN group. The reverse fox finger task was more challenging, completed by only 21.7%. The sensitivity of the reverse fox finger task for detecting dementia and MCI was 88.5% and 79.1%, respectively, whereas the fox finger task showed lower sensitivity (36.1% and 13.9%, respectively) but higher specificity (100% vs 62.5%). Fox finger failure was associated with atrophy in the bilateral inferior frontal gyri and left frontal pole. Reverse fox finger failure was linked to more widespread atrophy, including the left angular gyrus, right hippocampus, and right posterior cingulate gyrus. Binary logistic regression confirmed that reduced gray matter volume in these regions significantly predicted task failure (p<0.05). CONCLUSION: The reverse fox finger task offers high sensitivity for detecting early cognitive decline, while the fox finger task provides high specificity, supporting their clinical use as rapid, non-invasive screening tools.

Colon perforation with fecal peritonitis is usually fatal without prompt surgical intervention. We report the case of an 89-year-old woman with colon perforation and extraluminal feces who survived for 174 days without surgery in the presence of extensive postoperative peritoneal adhesions. The patient had previously undergone two abdominal surgeries for colorectal cancer, resulting in severe intra-abdominal adhesions. Despite radiological evidence of intraperitoneal free air and extraluminal feces, she was managed conservatively with antibiotics, morphine hydrochloride, supportive care, and close monitoring. This case suggests that, in carefully selected patients with marked peritoneal adhesions, non-operative management may warrant reconsideration as a potential therapeutic option for colon perforation before deeming that the condition is inoperable.