Browsing by Author "KBASE Research Group"

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    Association between brain tau deposition and default mode network connectivity in cognitively normal older adults
    (Wiley, 2025-01-09) Cha, Woo-Jin; Yi, Dahyun; Chumin, Evgeny J.; Byun, Min Soo; Jung, Joon Hyung; Ahn, Hyejin; Kim, Yu Kyeong; Lee, Yun-Sang; Kang, Koung Mi; Sohn, Chul-Ho; Risacher, Shannon L.; Sporns, Olaf; Nho, Kwangsik; Saykin, Andrew J.; Lee, Dong Young; KBASE Research Group; Radiology and Imaging Sciences, School of Medicine
    Background: Alzheimer’s disease (AD) pathology occurs in the brain before manifestation of significant cognitive decline. Growing evidence suggests that brain networks such as default mode network (DMN) or salience network, identified through resting‐state functional magnetic resonance imaging (MRI), are affected by AD pathology. In this study, we investigated the relationship between network segregation and the key in vivo AD pathologies including beta‐amyloid (Aβ) and tau deposition in old adults with no cognitive impairment. Method: A total 283 older adults with normal cognition aging from 55 to 87 were recruited from the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer’s Disease (KBASE) cohort. The participants underwent comprehensive clinical and neuropsychological assessment, [11C] Pittsburgh Compound B PET for measuring Aβ deposition, [18F] AV‐1451 PET for measuring tau deposition, structural MRI, and resting‐state functional MRI for measuring functional connectivity (FC). For PET scans, standard uptake value ratio (SUVR) was used for the analyses; combined regions of inferior cerebellum and pons were used as the reference region when obtaining SUVRs. For FC, segregation values (ratios between median z‐transformed Pearson correlation of within‐ and between‐network connectivity) for overall and the seven individual resting state networks were computed (Table). The relationships between Aβ or tau deposition and network connectivity segregation were examined through cross‐sectional approach using multiple regression analyses. In the analyses, Aβ or tau deposition was used as an independent variable and segregation values of the networks were used as dependent variables. Result: Tau deposition had a significant negative association with the DMN segregation (β = ‐0.249, p = 0.007); but, tau had no relationships with any other networks (Table). Aβ deposition was not associated with any segregation values for the seven brain networks (Table). Conclusion: Our finding suggests that impaired functional connectivity of DMN is closely linked to tau deposition even in cognitively unimpaired older individuals.
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    Association of amyloid and cardiovascular risk with cognition: Findings from KBASE
    (Wiley, 2024) Chaudhuri, Soumilee; Dempsey, Desarae A.; Huang, Yen-Ning; Park, Tamina; Cao, Sha; Chumin, Evgeny J.; Craft, Hannah; Crane, Paul K.; Mukherjee, Shubhabrata; Choi, Seo-Eun; Scollard, Phoebe; Lee, Michael; Nakano, Connie; Mez, Jesse; Trittschuh, Emily H.; Klinedinst, Brandon S.; Hohman, Timothy J.; Lee, Jun-Young; Kang, Koung Mi; Sohn, Chul-Ho; Kim, Yu Kyeong; Yi, Dahyun; Byun, Min Soo; Risacher, Shannon L.; Nho, Kwangsik; Saykin, Andrew J.; Lee, Dong Young; KBASE Research Group; Radiology and Imaging Sciences, School of Medicine
    Background: Limited research has explored the effect of cardiovascular risk and amyloid interplay on cognitive decline in East Asians. Methods: Vascular burden was quantified using Framingham's General Cardiovascular Risk Score (FRS) in 526 Korean Brain Aging Study (KBASE) participants. Cognitive differences in groups stratified by FRS and amyloid positivity were assessed at baseline and longitudinally. Results: Baseline analyses revealed that amyloid-negative (Aβ-) cognitively normal (CN) individuals with high FRS had lower cognition compared to Aβ- CN individuals with low FRS (p < 0.0001). Longitudinally, amyloid pathology predominantly drove cognitive decline, while FRS alone had negligible effects on cognition in CN and mild cognitive impairment (MCI) groups. Conclusion: Our findings indicate that managing vascular risk may be crucial in preserving cognition in Aβ- individuals early on and before the clinical manifestation of dementia. Within the CN and MCI groups, irrespective of FRS status, amyloid-positive individuals had worse cognitive performance than Aβ- individuals. Highlights: Vascular risk significantly affects cognition in amyloid-negative older Koreans. Amyloid-negative CN older adults with high vascular risk had lower baseline cognition. Amyloid pathology drives cognitive decline in CN and MCI, regardless of vascular risk. The study underscores the impact of vascular health on the AD disease spectrum.
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    Locus coeruleus tau is linked to successive cortical tau accumulation
    (Wiley, 2025) Yi, Dahyun; Byun, Min Soo; Jung, Joon Hyung; Jung, Gijung; Ahn, Hyejin; Chang, Yoon Young; Keum, Musung; Lee, Jun-Young; Lee, Yun-Sang; Kim, Yu Kyeong; Kang, Koung Mi; Sohn, Chul-Ho; Risacher, Shannon L.; Saykin, Andrew J.; Lee, Dong Young; KBASE Research Group; Radiology and Imaging Sciences, School of Medicine
    Introduction: We investigated the hypothesis that tau burden in the locus coeruleus (LC) correlates with tau accumulation in cortical regions according to the Braak stages and examined whether the relationships differed according to cortical amyloid beta (Aβ) deposition. Methods: One hundred and seventy well-characterized participants from an ongoing cohort were included. High-resolution T1, tau positron emission tomography (PET), and amyloid PET were obtained. Results: LC tau burden was significantly linked to global tau in neocortical regions, as was tau in both early Braak stage (stage I/II) and later Braak stage areas. This relationship was significant only in Aβ-positive individuals. While LC tau did not directly impact memory, it was indirectly associated with delayed memory through mediation or moderation pathways. Discussion: The findings from living human brains support the idea that LC tau closely relates to subsequent cortical tau accumulation, particularly among individuals with pathological Aβ accumulation, and identify LC tau burden as a promising indicator of cognitive trajectories of AD. Highlights: Tau burden in the LC was significantly associated with cortical tau accumulation. Tau burden in SN or PPN showed no association with cortical tau accumulation. LC tau burden was serially associated with Braak stages. The tau-LC and cortical tau relationship was significant only in the Aβ-positive group. Cortical amyloid's impact on memory worsens with higher tau accumulation in the LC.
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    White matter integrity is associated with cognition and amyloid burden in older adult Koreans along the Alzheimer's disease continuum
    (Springer Nature, 2023-12-16) Hirschfeld, Lauren R.; Deardorff, Rachael; Chumin, Evgeny J.; Wu, Yu‑Chien; McDonald, Brenna C.; Cao, Sha; Risacher, Shannon L.; Yi, Dahyun; Byun, Min Soo; Lee, Jun‑Young; Kim, Yu Kyeong; Kang, Koung Mi; Sohn, Chul‑Ho; Nho, Kwangsik; Saykin, Andrew J.; Lee, Dong Young; KBASE Research Group; Radiology and Imaging Sciences, School of Medicine
    Background: White matter (WM) microstructural changes in the hippocampal cingulum bundle (CBH) in Alzheimer's disease (AD) have been described in cohorts of largely European ancestry but are lacking in other populations. Methods: We assessed the relationship between CBH WM integrity and cognition or amyloid burden in 505 Korean older adults aged ≥ 55 years, including 276 cognitively normal older adults (CN), 142 with mild cognitive impairment (MCI), and 87 AD patients, recruited as part of the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer's disease (KBASE) at Seoul National University. Results: Compared to CN, AD and MCI subjects showed significantly higher RD, MD, and AxD values (all p-values < 0.001) and significantly lower FA values (left p ≤ 0.002, right p ≤ 0.015) after Bonferroni adjustment for multiple comparisons. Most tests of cognition and mood (p < 0.001) as well as higher medial temporal amyloid burden (p < 0.001) were associated with poorer WM integrity in the CBH after Bonferroni adjustment. Conclusion: These findings are consistent with patterns of WM microstructural damage previously reported in non-Hispanic White (NHW) MCI/AD cohorts, reinforcing existing evidence from predominantly NHW cohort studies.
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    White matter integrity is associated with cognition and amyloid burden in older adult Koreans along the Alzheimer's disease continuum
    (medRxiv, 2023-04-06) Hirschfeld, Lauren Rose; Deardorff, Rachael; Chumin, Evgeny J.; Wu, Yu-Chien; McDonald, Brenna C.; Cao, Sha; Risacher, Shannon L.; Yi, Dahyun; Byun, Min Soo; Lee, Jun-Young; Kim, Yu Kyeong; Kang, Koung Mi; Sohn, Chul-Ho; Nho, Kwangsik; Saykin, Andrew J.; Lee, Dong Young; KBASE Research Group; Radiology and Imaging Sciences, School of Medicine
    Background: White matter (WM) microstructural changes in the hippocampal cingulum bundle (CBH) in Alzheimer's disease (AD) have been described in cohorts of largely European ancestry but are lacking in other populations. Methods: We assessed the relationship between CBH WM integrity and cognition or amyloid burden in 505 Korean older adults aged ≥55 years, including 276 cognitively normal older adults (CN), 142 mild cognitive impairment (MCI), and 87 AD, recruited as part of the Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer's disease (KBASE) at Seoul National University. Results: Compared to CN, AD and MCI subjects showed decreased WM integrity in the bilateral CBH. Cognition, mood, and higher amyloid burden were also associated with poorer WM integrity in the CBH. Conclusion: These findings are consistent with patterns of WM microstructural damage previously reported in non-Hispanic White (NHW) MCI/AD cohorts, reinforcing existing evidence from predominantly NHW cohort studies.