Publications by authors named "Hyun-Kook Lim"

Article Synopsis
  • The study compared the performance of two MR volumetry segmentation tools, FreeSurfer and Neurophet AQUA, at different magnetic field strengths (1.5T and 3T) using data from 213 patients across multiple sources.
  • It found that FreeSurfer reported larger hippocampus volumes while Neurophet AQUA exhibited lower average volume differences and more stable segmentation across brain regions.
  • Additionally, Neurophet AQUA proved significantly faster, taking only 5 minutes for segmentation compared to 1 hour for FreeSurfer, suggesting a trade-off between accuracy, consistency, and processing time in choosing a segmentation method.
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Background: The interrelation between infections, subjective cognitive decline (SCD), and dementia development is recognized, but not fully understood. This study explored the combined effect of specific infections and SCD on the risk of dementia.

Objectives: To assess the influence of , herpes simplex virus, varicella-zoster virus, and human papillomavirus on dementia risk in individuals with varying cognitive statuses, especially focusing on those with and without SCD.

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Background: Alzheimer's disease (AD) encompasses a spectrum that may progress from mild cognitive impairment (MCI) to full dementia, characterized by amyloid-beta and tau accumulation. Transcranial direct current stimulation (tDCS) is being investigated as a therapeutic option, but its efficacy in relation to individual genetic and biological risk factors remains underexplored.

Objective: To evaluate the effects of a two-week anodal tDCS regimen on the left dorsolateral prefrontal cortex, focusing on functional connectivity changes in neural networks in MCI patients resulting from various possible underlying disorders, considering individual factors associated to AD such as amyloid-beta deposition, ϵ4 allele, BDNF Val66Met polymorphism, and sex.

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Background/aims: Alcohol-associated liver disease (ALD) is a public health concern. ALD patients often have psychiatric comorbidities, but the effects of psychiatric interventions on ALD are not well-established. This study explores the prognostic impact of psychiatric intervention on ALD within UK Biobank cohort.

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Despite the growing interest in precision medicine-based therapies for Alzheimer's disease (AD), little research has been conducted on how individual AD risk factors influence changes in cognitive function following transcranial direct current stimulation (tDCS). This study evaluates the cognitive effects of sequential tDCS on 63 mild cognitive impairment (MCI) patients, considering AD risk factors such as amyloid-beta deposition, APOE ε4, BDNF polymorphism, and sex. Using both frequentist and Bayesian methods, we assessed the interaction of tDCS with these risk factors on cognitive performance.

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The impact of peptic ulcer disease (PUD) and Helicobacter pylori (H. pylori) eradication therapy on dementia risk in high H. pylori prevalence populations remains uncertain.

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Accurate quantification of amyloid positron emission tomography (PET) is essential for early detection of and intervention in Alzheimer's disease (AD) but there is still a lack of studies comparing the performance of various automated methods. This study compared the PET-only method and PET-and-MRI-based method with a pre-trained deep learning segmentation model. A large sample of 1180 participants in the Catholic Aging Brain Imaging (CABI) database was analyzed to calculate the regional standardized uptake value ratio (SUVR) using both methods.

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Article Synopsis
  • The study aims to enhance the diagnosis of Alzheimer's disease (AD) by implementing automated scoring methods for brain atrophy using deep learning techniques, addressing limitations of traditional visual scoring.* -
  • Involving nearly 4,000 participants, the research compared results from automated scoring methods and visual assessments performed by neuroradiologists to evaluate their consistency and reliability.* -
  • Findings indicate strong correlations between automated and visual scores for AD subtyping, suggesting automated methods could improve clinical assessments in large-scale studies.*
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Introduction: Despite prior research on the association between sarcopenia and cognitive impairment in the elderly, a comprehensive model that integrates various brain pathologies is still lacking.

Methods: We used data from 528 non-demented older adults with or without sarcopenia in the Catholic Aging Brain Imaging (CABI) database, containing magnetic resonance imaging scans, positron emission tomography scans, and clinical data. We also measured three key components of sarcopenia: skeletal muscle index (SMI), hand grip strength (HGS), and the five times sit-to-stand test (5STS).

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  • The review assesses how serious games can benefit patients with mild cognitive impairment (MCI) based on various randomized clinical trials (RCTs).
  • Eight RCTs were analyzed; findings showed that serious games can enhance cognitive function, quality of life, and even reduce depressive symptoms, with personalized and physical exercise-based games yielding the best results.
  • The conclusion emphasizes that while serious games show promise, more research and standardized methods are necessary to fully explore their effectiveness in cognitive rehabilitation for MCI patients.
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Article Synopsis
  • Alzheimer's disease (AD) is a major cause of dementia, affecting 60-70% of dementia patients, with mild cognitive impairment (MCI) serving as a precursor stage where about 10-15% of individuals transition to AD each year.
  • This study analyzed data from 196 subjects to identify the best combination of imaging features and machine learning models to predict the conversion from MCI to AD over a four-year follow-up, finding that 24% of patients progressed to AD.
  • The Gradient Boosting Machine (GBM) model proved to be the most reliable, demonstrating that omitting certain imaging features can enhance prediction accuracy, thereby aiding clinicians in early diagnosis and treatment planning for MCI patients.
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Background: Recent interest has surged in the locus coeruleus (LC) for its early involvement in Alzheimer's disease (AD), notably concerning the apolipoprotein ɛ4 allele (APOE4).

Objective: This study aimed to discern LC functional connectivity (FC) variations in preclinical AD subjects, dissecting the roles of APOE4 carrier status and amyloid-β (Aβ) deposition.

Methods: A cohort of 112 cognitively intact individuals, all Aβ-positive, split into 70 APOE4 noncarriers and 42 carriers, underwent functional MRI scans, neuropsychological assessments, and APOE genotyping.

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Introduction: Transcranial direct current stimulation (tDCS) may effectively preserve and improve cognitive function in patients with mild cognitive impairment (MCI). Research has shown that Individual brain characteristics can influence the effects of tDCS. Computer three-dimensional brain modeling based on magnetic resonance imaging (MRI) has been suggested as an alternative for determining the most accurate tDCS electrode position based on the patients' individual brain characteristics to enhance tDCS effects.

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Article Synopsis
  • * The review analyzed clinical trials showing that psilocybin, acting on serotonin receptors, can reduce depressive symptoms, improve cognitive biases, and have sustained effects on mental health.
  • * Among the clinical trials, significant reductions in anxiety and depression were observed with psilocybin, especially in cancer patients and those with major depressive disorder, suggesting its potential as a superior treatment option.
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Background: Multimer detection system-oligomeric amyloid-β (MDS-OAβ) is a measure of plasma OAβ, which is associated with Alzheimer's disease (AD) pathology. However, the relationship between MDS-OAβ and disease severity of AD is not clear. We aimed to investigate MDS-OAβ levels in different stages of AD and analyze the association between MDS-OAβ and cerebral Aβ deposition, cognitive function, and cortical thickness in subjects within the AD continuum.

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Objective: We aimed to create an efficient and valid predicting model which can estimate individuals' brain age by quantifying their regional brain volumes.

Methods: A total of 2,560 structural brain magnetic resonance imaging (MRI) scans, along with demographic and clinical data, were obtained. Pretrained deep-learning models were employed to automatically segment the MRI data, which enabled fast calculation of regional brain volumes.

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Objective: : Cognitive reserve has emerged as a concept to explain the variable expression of clinical symptoms in the pathology of Alzheimer's disease (AD). The association between years of education, a proxy of cognitive reserve, and resting-state functional connectivity (rFC), a representative intermediate phenotype, has not been explored in the preclinical phase, considering risk factors for AD. We aimed to evaluate whether the relationship between years of education and rFC in cognitively preserved older adults differs depending on amyloid-beta deposition and ε4 carrier status as effect modifiers.

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Objective: We aimed to evaluate the impact of interaction between APOE ε4 carrier status and body composition measurements on intra- and inter-regional functional connectivity (FC) in mild cognitive impairment (MCI) patients with Aβ deposition.

Methods: MCI patients with and without APOE ε4 allele (carrier, n=86; non-carrier, n=95) underwent neuropsychological battery, resting-state functional magnetic resonance imaging scans, positron emission tomography scans with [18F]flutemetamol, and bioelectrical impedance analysis for measuring body composition. We employed a priori defined regions of interest to investigate the intra- and inter-network FC profiles of default mode network (DMN), central executive network (CEN), and salience network.

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Background: Brain volume is associated with cognitive decline in later life, and cortical brain atrophy exceeding the normal range is related to inferior cognitive and behavioral outcomes in later life.

Objective: To investigate the likelihood of cognitive decline, mild cognitive impairment (MCI), or dementia, when regional atrophy is present in participants' magnetic resonance imaging (MRI).

Methods: Multi-center MRI data of 2,545 adults were utilized to measure regional volumes using NEUROPHET AQUA.

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Objective: Apolipoprotein E (APOE) gene is known to influence cerebral functional connectivity (FC) in Alzheimer's disease continuum. We investigated association between APOE allotypes and FC, structural connectivity, and cortical thickness in amyloid-PET negative cognitive normal older adults (CN).

Methods: A total of 188 CN (37 had ε2/ε2 or ε2/ε3 [ε2 group], 113 had ε3/ε3 [ε3 group], and 38 had ε3/ε4 or ε4/ε4 [ε4 group]) were recruited.

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Objective: Granulocyte colony-stimulating factor (G-CSF) is a growth factor used to regulate the mobilization of bone marrow progenitor cells and has been shown to promote brain repair and reduce inflammation. This study aimed to investigate the pro-cognitive and neuroplastic effects of G-CSF in healthy adults.

Methods: Sixteen healthy adults or donors of hematopoietic stem cell transplantation received G-CSF injections for 5 consecutive days, and their blood samples were collected before, immediately after, and 3 weeks after the G-CSF injections.

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Recent studies have demonstrated the pivotal role of locus coeruleus (LC) and salience network (SN) resting state functional connectivity (rsFC) changes in the early stage of Alzheimer's disease (AD). Moreover, sex has been a crucial point of discussion in understanding AD pathology. We aimed to demonstrate the sex-related disparities in the functional connectivity (FC) of the SN and LC in preclinical AD.

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Background: Multimer detection system-oligomeric amyloid-β (MDS-OAβ) measure plasma OAβ level, which is associated with earlier Alzheimer's disease (AD) pathology. However, no study has investigated MDS-OAβ differences in cognitive normal older adults (CN) with or without cerebral Aβ burden and its correlation with Aβ deposition and white matter (WM) integrity.

Objective: To investigate associations among cerebral Aβ burden, MDS-OAβ, and WM integrity in CN.

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Background: Education years, as a measure of cognitive reserve, have been shown to affect the progression of Alzheimer's disease (AD), both pathologically and clinically. However, inconsistent results have been reported regarding the association between years of education and intermediate structural changes in AD-vulnerable brain regions, particularly when AD risk factors were not considered during the preclinical phase.

Objective: This study aimed to examine how Aβ deposition and ε4 carrier status moderate the relationship between years of education and cortical volume in AD-vulnerable regions among cognitively normal older adults.

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Olfactory dysfunction is consistently observed in individuals with Alzheimer's disease (AD), but its association with beta-amyloid (Aβ) deposition remains unclear. This study aimed to investigate the relationship among olfactory function, cerebral Aβ deposition, and neuropsychological profiles in individuals with no cognitive impairment (NCI), mild cognitive impairment (MCI), and AD dementia. A total of 164 participants were included, and olfactory function was assessed using the brief smell identification test (B-SIT).

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