Browsing by Author "O’Bryant, Sid E."

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    Comparison of amyloid accumulation between Down syndrome and autosomal-dominant Alzheimer disease
    (Wiley, 2022) Boerwinkle, Anna H.; Gordon, Brian A.; Wisch, Julie K.; Flores, Shaney; Henson, Rachel L.; Butt, Omar Hameed; Chen, Charles D.; Benzinger, Tammie L. S.; Fagan, Anne M.; Handen, Benjamin L.; Christian, Bradley T.; Head, Elizabeth; Mapstone, Mark; Klunk, William E.; Rafii, Michael S.; O’Bryant, Sid E.; Price, Julie C.; Schupf, Nicole; Laymon, Charles M.; Krinsky-McHale, Sharon J.; Lai, Florence; Rosas, H. Diana; Hartley, Sigan L.; Zaman, Shahid; Lott, Ira T.; Silverman, Wayne; Brickman, Adam M.; Lee, Joseph H.; Allegri, Ricardo Francisco; Berman, Sarah; Chhatwal, Jasmeer P.; Chui, Helena C.; Cruchaga, Carlos; Farlow, Martin R.; Fox, Nick C.; Goate, Alison; Day, Gregory S.; Graff-Radford, Neill R.; Jucker, Mathias; Lee, Jae-Hong; Levin, Johannes; Martins, Ralph N.; Mori, Hiroshi; Perrin, Richard J.; Salloway, Stephen P.; Sanchez-Valle, Raquel; Schofield, Peter R.; Xiong, Chengjie; Karch, Celeste M.; Hassenstab, Jason J.; McDade, Eric; Bateman, Randall J.; Ances, Beau M.; Neurology, School of Medicine
    Background: Given the triplication of chromosome 21 and the location of the amyloid precursor protein gene on chromosome 21, almost all adults with Down syndrome (DS) develop Alzheimer disease (AD)-like pathology and dementia during their lifetime. Comparing amyloid accumulation in DS to autosomal dominant AD (ADAD), another genetic form of AD, may improve our understanding of early AD pathology development. Method: We assessed amyloid positron emission tomography (PET) imaging in 192 participants with DS and 33 sibling controls from the Alzheimer’s Biomarker Consortium-Down Syndrome (ABC-DS) and 265 mutation-carriers (MC) and 169 familial controls from the Dominantly Inherited Alzheimer Network (DIAN) (Table 1). We calculated regional standard uptake value ratios (SUVR) using a cerebellar cortex reference region and converted global amyloid burden SUVR to centiloids. We compared amyloid PET by cognitive status and estimated-years-to-symptom-onset (EYO). EYO was calculated for DIAN participants by subtracting their age from parental age of symptom onset and for ABC-DS participants by subtracting their age from 50.2 years, a published average age of symptom onset in a large sample of individuals with DS (Fortea et al., 2020). In a subset of participants, we assessed the relationship between amyloid PET and CSF Aβ42/40. Result: The relationship between CSF Aβ42/40 and amyloid PET was similar in DS and MC participants (Figure 1). We did not observe significant differences between MC and DS grouped by cognitive status (Figure 2). However, when assessed over EYO, global amyloid burden was significantly elevated in MC at EYO ≥ -23 but was not elevated in DS until EYO ≥ -15 (Figure 3). We observed early cortical and subcortical amyloid PET increases in both groups, but we also measured some regional differences in amyloid PET changes between MC and DS, specifically in the medial occipital region (Figure 4 and 5). Conclusion: These results demonstrate similarities in the relationship between amyloid biomarkers and the levels of amyloid accumulation in ADAD and DS. However, we also observed a 5-10 year delay and some regional differences in amyloid accumulation in DS. This is important for future clinical trials to consider when recruiting participants and determining treatment efficacy.
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    Guidelines for the standardization of preanalytic variables for blood-based biomarker studies in Alzheimer's disease research
    (Elsevier, 2015-05) O’Bryant, Sid E.; Gupta, Veer; Henriksen, Kim; Edwards, Melissa; Jeromin, Andreas; Lista, Simone; Bazenet, Chantal; Soares, Holly; Lovestone, Simon; Hampel, Harald; Montine, Thomas; Blennow, Kaj; Foroud, Tatiana; Carrillo, Maria; Graff-Radford, Neill; Laske, Christoph; Breteler, Monique; Shaw, Leslie; Trojanowski, John Q.; Schupf, Nicole; Rissman, Robert A.; Fagan, Anne M.; Oberoi, Pankaj; Umek, Robert; Weiner, Michael W.; Grammas, Paul; Posner, Holly; Martins, Ralph; Department of Medical & Molecular Genetics, IU School of Medicine
    The lack of readily available biomarkers is a significant hindrance towards progressing to effective therapeutic and preventative strategies for Alzheimer’s disease (AD). Blood-based biomarkers have potential to overcome access and cost barriers and greatly facilitate advanced neuroimaging and cerebrospinal fluid biomarker approaches. Despite the fact that preanalytical processing is the largest source of variability in laboratory testing, there are no currently available standardized preanalytical guidelines. The current international working group provides the initial starting point for such guidelines for standardized operating procedures (SOPs). It is anticipated that these guidelines will be updated as additional research findings become available. The statement provides (1) a synopsis of selected preanalytical methods utilized in many international AD cohort studies, (2) initial draft guidelines/SOPs for preanalytical methods, and (3) a list of required methodological information and protocols to be made available for publications in the field in order to foster cross-validation across cohorts and laboratories.
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    Independent and interactive contributions of cerebrovascular disease, neuroinflammation, and tau pathophysiology to Alzheimer’s disease‐related diagnostic conversion in adults with Down syndrome
    (Wiley, 2025-01-09) Edwards, Natalie C.; Lao, Patrick J.; Alshikho, Mohamad J.; Rizvi, Batool; Flores Aguilar, Lisi; Petersen, Melissa; O’Bryant, Sid E.; Tudorascu, Dana; Handen, Benjamin L.; Gutierrez, Jose; Wilcock, Donna M.; Head, Elizabeth; Brickman, Adam M.; Neurology, School of Medicine
    Background: By age 40 years, adults with Down syndrome (DS) develop Alzheimer’s disease (AD) pathology and progress to dementia in their 60s. Despite minimal systemic vascular risk factors, individuals with DS have MRI evidence of cerebrovascular injury that progresses with AD severity, suggesting an intrinsic vascular component to DS‐AD that may interact with neuroinflammatory processes to promote tau pathology and cognitive decline. In the current study we examined whether cerebrovascular disease (CVD) burden and inflammation/astrocytosis independently and interactively were associated with incident diagnosis among adults with DS. Method: This study included 149 participants from the Alzheimer Biomarkers Consortium – Down Syndrome (baseline mean age[SD]=44.6[9] years) with available baseline MRI, plasma biomarker data, and at least two time‐points of clinical consensus diagnosis data (i.e., cognitively stable, mild cognitive impairment [MCI], and clinical AD) who were classified as cognitively stable or MCI at baseline. Logistic regression models assessed if baseline small vessel CVD, operationalized as white matter hyperintensity (WMH) volume, and plasma glial fibrillary acidic protein (GFAP), Aβ42/Aβ40, p‐tau217, and neurofilament light (NfL) concentrations are associated with conversion from a milder diagnosis to a more severe clinical diagnosis. Mediation models examined relationships between biomarkers and diagnostic conversion. All models adjusted for study site, sex/gender, latency between visit dates, and age group (below or above/equal to the median age of the sample). Result: Diagnostic conversion occurred in 26% of the sample. Higher baseline WMH volume (OR 1.08 [1.01, 1.81]), GFAP (OR 1.006 [1.003, 1.01]), and p‐tau217 (OR 20.56 [5.01, 112.43]), but not NfL nor Aβ42/Aβ40 concentrations were associated with higher odds of conversion to more severe cognitive impairment. GFAP concentration mediated the relationship between WMH and diagnostic conversion (ACME 0.05 [0.01, 0.1], p=0.006). P‐tau217 concentration mediated the relationship between GFAP and diagnostic conversion (ACME 0.13 [0.05, 0.23], p=0.004). Conclusion: Our findings suggest that among individuals with DS, CVD promotes AD‐related clinical progression by increasing astrocytosis which, in turn, promotes tau pathophysiology and downstream MCI and AD incidence. The results implicate CVD and its interface with inflammation as a core feature of AD in DS.