Alterations in hippocampus-centered morphological features and function of the progression from normal cognition to mild cognitive impairment.

Mild cognitive impairment (MCI) is a significant precursor to dementia, highlighting the critical need for early identification of individuals at high risk of MCI to prevent cognitive decline. The study aimed to investigate the changes in brain structure and function before the onset of MCI. This study enrolled 19 older adults with progressive normal cognition (pNC) to MCI and 19 older adults with stable normal cognition (sNC). The gray matter (GM) volume and functional connectivity (FC) were estimated via magnetic resonance imaging during their normal cognition state 3 years prior. Additionally, spatial associations between FC maps and neurochemical profiles were examined using JuSpace. Compared to the sNC group, the pNC group showed decreased volume in the left hippocampus and left amygdala. The significantly positive correlation was observed between the GM volume of the left hippocampus and the MMSE scores after 3 years in pNC group. Besides, it showed that the pNC group had increased FC between the left hippocampus and the anterior-posterior cingulate gyrus, which was significantly correlated with the spatial distribution of dopamine D2 and noradrenaline transporter. Taken together, the study identified the abnormal brain characteristics before the onset of MCI, which might provide insight into clinical research.

Altered morphological characteristics and structural covariance connectivity associated with verbal working memory performance in ADHD children.

OBJECTIVES: Deficits in verbal working memory (VWM) observed in attention deficit hyperactivity disorder (ADHD) children can persist into adulthood. Although previous studies have identified brain regions that are activated during VWM tasks, the neural mechanisms underlying the relationship between VWM deficits remain unclear. The objective of this study was to investigate the structural covariance network connectivity and brain morphology changes that are associated with VWM performance in ADHD children. METHODS: For this study, we selected 26 ADHD children and 26 healthy control (HC) participants. Participants were instructed to perform an n-back VWM task and their accuracy and response times were subsequently recorded. This research utilised voxel-based morphometry to measure the grey matter (GM) volume and conducted structural covariance connectivity network analysis to explore the changes of brain in ADHD. RESULTS: Voxel-based morphometry analysis showed that lower GM volume in the right cerebellum lobule VI and the left parahippocampal gryus in ADHD children. Moreover, a positive correlation was found between the GM volume in the right cerebellum lobule VI and the accuracy of 2-back VWM task with verbal, small reward, and delayed feedback (VSD). Structural covariance network analysis found decreased structural connectivity between right cerebellum lobule VI and right precentral gyrus, right postcentral gyrus, left paracentral lobule, right superior parietal gyrus, and left hippocampus in ADHD children. CONCLUSIONS: The low GM volume and altered structural covariance connectivity in the right cerebellum lobule VI might potentially affect VWM performance in ADHD children. ADVANCES IN KNOWLEDGE: The innovation of this study lies in its more focused discussion on the morphological characteristics and structural covariance connectivity of VWM deficits in ADHD children, and the innovative finding of a positive correlation between grey matter volume in the right cerebellum lobule VI and accuracy in completing the 2-back VWM task with verbal instructions, small reward, and delayed feedback (VSD). This expands upon previous research by elucidating the specific brain structures involved in VWM deficits in ADHD children and highlights the potential importance of the cerebellum in this cognitive process. Overall, these innovative findings advance our understanding of the neural basis of ADHD and may have important implications for the development of targeted interventions for VWM deficits.