Browsing by Author "Lockhart, Samuel N."

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    Associations among plasma, MRI, and amyloid PET biomarkers of Alzheimer's disease and related dementias and the impact of health‐related comorbidities in a community‐dwelling cohort
    (Wiley, 2024) Rudolph, Marc D.; Sutphen, Courtney L.; Register, Thomas C.; Whitlow, Christopher T.; Solingapuram Sai, Kiran K.; Hughes, Timothy M.; Bateman, James R.; Dage, Jeffrey L.; Russ, Kristen A.; Mielke, Michelle M.; Craft, Suzanne; Lockhart, Samuel N.; Neurology, School of Medicine
    Introduction: We evaluated associations between plasma and neuroimaging-derived biomarkers of Alzheimer's disease and related dementias and the impact of health-related comorbidities. Methods: We examined plasma biomarkers (neurofilament light chain, glial fibrillary acidic protein, amyloid beta [Aβ] 42/40, phosphorylated tau 181) and neuroimaging measures of amyloid deposition (Aβ-positron emission tomography [PET]), total brain volume, white matter hyperintensity volume, diffusion-weighted fractional anisotropy, and neurite orientation dispersion and density imaging free water. Participants were adjudicated as cognitively unimpaired (CU; N = 299), mild cognitive impairment (MCI; N = 192), or dementia (DEM; N = 65). Biomarkers were compared across groups stratified by diagnosis, sex, race, and APOE ε4 carrier status. General linear models examined plasma-imaging associations before and after adjusting for demographics (age, sex, race, education), APOE ε4 status, medications, diagnosis, and other factors (estimated glomerular filtration rate [eGFR], body mass index [BMI]). Results: Plasma biomarkers differed across diagnostic groups (DEM > MCI > CU), were altered in Aβ-PET-positive individuals, and were associated with poorer brain health and kidney function. Discussion: eGFR and BMI did not substantially impact associations between plasma and neuroimaging biomarkers. Highlights: Plasma biomarkers differ across diagnostic groups (DEM > MCI > CU) and are altered in Aβ-PET-positive individuals. Altered plasma biomarker levels are associated with poorer brain health and kidney function. Plasma and neuroimaging biomarker associations are largely independent of comorbidities.
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    Emerging role of vascular burden in AT(N) classification in individuals with Alzheimer's and concomitant cerebrovascular burdens
    (BMJ, 2023-12-14) Chun, Min Young; Jang, Hyemin; Kim, Soo-Jong; Park, Yu Hyun; Yun, Jihwan; Lockhart, Samuel N.; Weiner, Michael; De Carli, Charles; Moon, Seung Hwan; Choi, Jae Yong; Nam, Kyung Rok; Byun, Byung-Hyun; Lim, Sang-Moo; Kim, Jun Pyo; Choe, Yeong Sim; Kim, Young Ju; Na, Duk L.; Kim, Hee Jin; Seo, Sang Won; Radiology and Imaging Sciences, School of Medicine
    Objectives: Alzheimer's disease (AD) is characterised by amyloid-beta accumulation (A), tau aggregation (T) and neurodegeneration (N). Vascular (V) burden has been found concomitantly with AD pathology and has synergistic effects on cognitive decline with AD biomarkers. We determined whether cognitive trajectories of AT(N) categories differed according to vascular (V) burden. Methods: We prospectively recruited 205 participants and classified them into groups based on the AT(N) system using neuroimaging markers. Abnormal V markers were identified based on the presence of severe white matter hyperintensities. Results: In A+ category, compared with the frequency of Alzheimer's pathological change category (A+T-), the frequency of AD category (A+T+) was significantly lower in V+ group (31.8%) than in V- group (64.4%) (p=0.004). Each AT(N) biomarker was predictive of cognitive decline in the V+ group as well as in the V- group (p<0.001). Additionally, the V+ group showed more severe cognitive trajectories than the V- group in the non-Alzheimer's pathological changes (A-T+, A-N+; p=0.002) and Alzheimer's pathological changes (p<0.001) categories. Conclusion: The distribution and longitudinal outcomes of AT(N) system differed according to vascular burdens, suggesting the importance of incorporating a V biomarker into the AT(N) system.