Keita Sakurai

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.

BackgroundArgyrophilic grain disease (AGD) is a common yet underrecognized tauopathy that often mimics Alzheimer's disease (AD) in clinical and imaging presentations. While regional atrophy in AGD has been reported on magnetic resonance imaging (MRI), network-level structural changes remain poorly understood.ObjectiveWe aimed to explore a gray matter volume network related to AGD.MethodsStructural MRI data were collected from 12 patients with pathologically confirmed AGD (age at MRI, 87.7 ± 5.5 years; male, 4), 12 patients with pathologically confirmed AD (83.4 ± 10.0 years; male, 4), and 9 healthy controls (HCs; 82.4 ± 1.9 years; male, 2) at Fukushimura Hospital in Japan. Scaled Subprofile Model with principal component analysis was applied to preprocessed gray matter volume data of AGD and HCs to identify an AGD-related network.ResultsAn AGD-related network involving relative reduction in the ambient gyrus, entorhinal cortex, hippocampus, amygdala, and thalamus was identified. Represented by principal components 1, 2, and 3, this network showed significantly higher expression in patients with AGD than HCs (p < 0.0001, permutation test). The expression of the network was also higher in patients with AD than HCs (p < 0.0001, t-test).ConclusionsThis exploratory study identified a gray matter volume network related to AGD, providing a basis for future research of network-based imaging approaches.