Browsing by Author "Christian, Bradley T."
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Item Cerebrovascular disease drives Alzheimer plasma biomarker concentrations in adults with Down syndrome(medRxiv, 2023-11-30) Edwards, Natalie C.; Lao, Patrick J.; Alshikho, Mohamad J.; Ericsson, Olivia M.; Rizvi, Batool; Petersen, Melissa E.; O’Bryant, Sid; Flores-Aguilar, Lisi; Simoes, Sabrina; Mapstone, Mark; Tudorascu, Dana L.; Janelidze, Shorena; Hansson, Oskar; Handen, Benjamin L.; Christian, Bradley T.; Lee, Joseph H.; Lai, Florence; Rosas, H. Diana; Zaman, Shahid; Lott, Ira T.; Yassa, Michael A.; Gutierrez, José; Wilcock, Donna M.; Head, Elizabeth; Brickman, Adam M.; Neurology, School of MedicineImportance: By age 40 years over 90% of adults with Down syndrome (DS) have Alzheimer's disease (AD) pathology and most progress to dementia. Despite having few systemic vascular risk factors, individuals with DS have elevated cerebrovascular disease (CVD) markers that track with the clinical progression of AD, suggesting a role for CVD that is hypothesized to be mediated by inflammatory factors. Objective: To examine the pathways through which small vessel CVD contributes to AD-related pathophysiology and neurodegeneration in adults with DS. Design: Cross sectional analysis of neuroimaging, plasma, and clinical data. Setting: Participants were enrolled in Alzheimer's Biomarker Consortium - Down Syndrome (ABC-DS), a multisite study of AD in adults with DS. Participants: One hundred eighty-five participants (mean [SD] age=45.2 [9.3] years) with available MRI and plasma biomarker data were included. White matter hyperintensity (WMH) volumes were derived from T2-weighted FLAIR MRI scans and plasma biomarker concentrations of amyloid beta (Aβ42/Aβ40), phosphorylated tau (p-tau217), astrocytosis (glial fibrillary acidic protein, GFAP), and neurodegeneration (neurofilament light chain, NfL) were measured with ultrasensitive immunoassays. Main outcomes and measures: We examined the bivariate relationships of WMH, Aβ42/Aβ40, p-tau217, and GFAP with age-residualized NfL across AD diagnostic groups. A series of mediation and path analyses examined causal pathways linking WMH and AD pathophysiology to promote neurodegeneration in the total sample and groups stratified by clinical diagnosis. Results: There was a direct and indirect bidirectional effect through GFAP of WMH on p-tau217 concentration, which was associated with NfL concentration in the entire sample. Among cognitively stable participants, WMH was directly and indirectly, through GFAP, associated with p-tau217 concentration, and in those with MCI, there was a direct effect of WMH on p-tau217 and NfL concentrations. There were no associations of WMH with biomarker concentrations among those diagnosed with dementia. Conclusions and relevance: The findings suggest that among individuals with DS, CVD promotes neurodegeneration by increasing astrocytosis and tau pathophysiology in the presymptomatic phases of AD. This work joins an emerging literature that implicates CVD and its interface with neuroinflammation as a core pathological feature of AD in adults with DS.Item Cerebrovascular disease emerges with age and Alzheimer's disease in adults with Down syndrome(Springer Nature, 2024-05-29) Lao, Patrick; Edwards, Natalie; Flores‑Aguilar, Lisi; Alshikho, Mohamad; Rizvi, Batool; Tudorascu, Dana; Rosas, H. Diana; Yassa, Michael; Christian, Bradley T.; Mapstone, Mark; Handen, Benjamin; Zimmerman, Molly E.; Gutierrez, Jose; Wilcock, Donna; Head, Elizabeth; Brickman, Adam M.; Neurology, School of MedicineAdults with Down syndrome have a genetic form of Alzheimer's disease (AD) and evidence of cerebrovascular disease across the AD continuum, despite few systemic vascular risk factors. The onset and progression of AD in Down syndrome is highly age-dependent, but it is unknown at what age cerebrovascular disease emerges and what factors influence its severity. In the Alzheimer's Biomarker Consortium-Down Syndrome study (ABC-DS; n = 242; age = 25-72), we estimated the age inflection point at which MRI-based white matter hyperintensities (WMH), enlarged perivascular spaces (PVS), microbleeds, and infarcts emerge in relation to demographic data, risk factors, amyloid and tau, and AD diagnosis. Enlarged PVS and infarcts appear to develop in the early 30s, while microbleeds, WMH, amyloid, and tau emerge in the mid to late 30s. Age-residualized WMH were higher in women, in individuals with dementia, and with lower body mass index. Participants with hypertension and APOE-ε4 had higher age-residualized PVS and microbleeds, respectively. Lifespan trajectories demonstrate a dramatic cerebrovascular profile in adults with Down syndrome that appears to evolve developmentally in parallel with AD pathophysiology approximately two decades prior to dementia symptoms.Item Cerebrovascular disease is associated with Alzheimer's plasma biomarker concentrations in adults with Down syndrome(Oxford University Press, 2024-09-25) Edwards, Natalie C.; Lao, Patrick J.; Alshikho, Mohamad J.; Ericsson, Olivia M.; Rizvi, Batool; Petersen, Melissa E.; O’Bryant, Sid; Flores Aguilar, Lisi; Simoes, Sabrina; Mapstone, Mark; Tudorascu, Dana L.; Janelidze, Shorena; Hansson, Oskar; Handen, Benjamin L.; Christian, Bradley T.; Lee, Joseph H.; Lai, Florence; Rosas, H. Diana; Zaman, Shahid; Lott, Ira T.; Yassa, Michael A.; Alzheimer’s Biomarkers Consortium–Down Syndrome (ABC-DS) Investigators; Gutierrez, José; Wilcock, Donna M.; Head, Elizabeth; Brickman, Adam M.; Neurology, School of MedicineBy age 40 years, over 90% of adults with Down syndrome have Alzheimer's disease pathology and most progress to dementia. Despite having few systemic vascular risk factors, individuals with Down syndrome have elevated cerebrovascular disease markers that track with the clinical progression of Alzheimer's disease, suggesting a role of cerebrovascular disease that is hypothesized to be mediated by inflammatory factors. This study examined the pathways through which small vessel cerebrovascular disease contributes to Alzheimer's disease-related pathophysiology and neurodegeneration in adults with Down syndrome. One hundred eighty-five participants from the Alzheimer's Biomarkers Consortium-Down Syndrome [mean (SD) age = 45.2 (9.3) years] with available MRI and plasma biomarker data were included in this study. White matter hyperintensity (WMH) volumes were derived from T2-weighted fluid-attenuated inversion recovery MRI scans, and plasma biomarker concentrations of amyloid beta 42/40, phosphorylated tau 217, astrocytosis (glial fibrillary acidic protein) and neurodegeneration (neurofilament light chain) were measured with ultrasensitive immunoassays. We examined the bivariate relationships of WMH, amyloid beta 42/40, phosphorylated tau 217 and glial fibrillary acidic protein with age-residualized neurofilament light chain across Alzheimer's disease diagnostic groups. A series of mediation and path analyses examined statistical pathways linking WMH and Alzheimer's disease pathophysiology to promote neurodegeneration in the total sample and groups stratified by clinical diagnosis. There was a direct and indirect bidirectional effect through the glial fibrillary acidic protein of WMH on phosphorylated tau 217 concentration, which was associated with neurofilament light chain concentration in the entire sample. Amongst cognitively stable participants, WMH was directly and indirectly, through glial fibrillary acidic protein, associated with phosphorylated tau 217 concentration, and in those with mild cognitive impairment, there was a direct effect of WMH on phosphorylated tau 217 and neurofilament light chain concentrations. There were no associations of WMH with biomarker concentrations among those diagnosed with dementia. The findings from this cross-sectional study suggest that among individuals with Down syndrome, cerebrovascular disease promotes neurodegeneration by increasing astrocytosis and tau pathophysiology in the presymptomatic phases of Alzheimer's disease, but future studies will need to confirm these associations with longitudinal data. This work joins an emerging literature that implicates cerebrovascular disease and its interface with neuroinflammation as a core pathological feature of Alzheimer's disease in adults with Down syndrome.Item 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 MedicineBackground: 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.Item Cortical Dopamine Release During a Behavioral Response Inhibition Task(Wiley, 2014) Albrecht, Daniel S.; Kareken, David A.; Christian, Bradley T.; Dzemidzic, Mario; Yoder, Karmen K.; Radiology and Imaging Sciences, School of MedicineDopamine (DA) dysregulation within fronto-striatal circuitry may underlie impulsivity in alcohol and other substance use disorders. To date, no one has directly demonstrated DA release during a task requiring the control of impulsive behavior. The current study was conducted to determine whether a response inhibition task (stop signal task; SST) would elicit detectable extrastriatal DA release in healthy controls. We hypothesized that DA release would be detected in regions previously implicated in different aspects of inhibitory control. [18F]Fallypride (FAL) PET imaging was performed in nine healthy males (24.6 ± 4.1 y.o.) to assess changes in cortical DA during a SST relative to a baseline “Go” task. On separate days, subjects received one FAL scan during the SST, and one FAL scan during a “Go” control; task-order was counter-balanced across subjects. Parametric BPND images were generated and analyzed with SPM8. Voxel-wise analysis indicated significant SST-induced DA release in several cortical regions involved in inhibitory control, including the insula, cingulate cortex, orbitofrontal cortex, precuneus, and supplementary motor area. There was a significant positive correlation between stop signal reaction time and DA release in the left orbitofrontal cortex, right middle frontal gyrus, and right precentral gyrus. These data support the feasibility of using FAL PET to study DA release during response inhibition, enabling investigation of relationships between DA function and impulsive behavior.Item Differential dopamine function in fibromyalgia(Springer, 2016-09) Albrecht, Daniel S.; MacKie, Palmer J.; Kareken, David A.; Hutchins, Gary D.; Chumin, Evgeny J.; Christian, Bradley T.; Yoder, Karmen K.; Radiology and Imaging Sciences, School of MedicineApproximately 30% of Americans suffer from chronic pain disorders, such as fibromyalgia (FM), which can cause debilitating pain. Many pain-killing drugs prescribed for chronic pain disorders are highly addictive, have limited clinical efficacy, and do not treat the cognitive symptoms reported by many patients. The neurobiological substrates of chronic pain are largely unknown, but evidence points to altered dopaminergic transmission in aberrant pain perception. We sought to characterize the dopamine (DA) system in individuals with FM. Positron emission tomography (PET) with [18F]fallypride (FAL) was used to assess changes in DA during a working memory challenge relative to a baseline task, and to test for associations between baseline D2/D3 availability and experimental pain measures. Twelve female subjects with FM and eleven female controls completed study procedures. Subjects received one FAL PET scan while performing a “2-back” task, and one while performing a “0-back” (attentional control, “baseline”) task. FM subjects had lower baseline FAL binding potential (BP) in several cortical regions relative to controls, including anterior cingulate cortex. In FM subjects, self-reported spontaneous pain negatively correlated with FAL BP in the left orbitofrontal cortex and parahippocampal gyrus. Baseline BP was significantly negatively correlated with experimental pain sensitivity and tolerance in both FM and CON subjects, although spatial patterns of these associations differed between groups. The data suggest that abnormal DA function may be associated with differential processing of pain perception in FM. Further studies are needed to explore the functional significance of DA in nociception and cognitive processing in chronic pain.Item Longitudinal changes in neuroimaging markers of small vessel disease: Implications for clinical trials(Wiley, 2025-01-09) Lao, Patrick J.; Edwards, Natalie C.; Flores-Aguilar, Lisi; Rizvi, Batool; Smith, Anna C.; Tudorascu, Dana; Rosas, H. Diana; Yassa, Michael A.; Handen, Benjamin L.; Christian, Bradley T.; Gutierrez, Jose; Wilcock, Donna M.; Head, Elizabeth; Brickman, Adam M.; Neurology, School of MedicineBackground: Adults with Down syndrome (DS) overproduce amyloid precursor protein, develop amyloid plaques at an early age, and are diagnosed with Alzheimer’s disease (AD) dementia at a high frequency. There is emerging evidence that cerebrovascular disease is elevated across the AD continuum in older adults with DS, independent of age and vascular risk, around the same time as amyloid and tau, but the regional rates of accumulation within individuals are unknown. Method: Adults with DS from the multisite Alzheimer’s Biomarker Consortium‐Down Syndrome study (ABC‐DS; n=78; age=50±6; 40% women) have two timepoints of T2 FLAIR MRI (1.2±0.6 years apart) quantified as white matter hyperintensity volume (WMH), which represents ischemic small vessel disease. Participants underwent consensus diagnosis at both timepoints (59% Cognitively‐Stable at both timepoints, 9% Cognitively‐Stable to MCI‐DS, 8% MCI‐DS at both timepoints, 14% MCI‐DS to AD, 10% AD at both timepoints). The annual rate of change in frontal, temporal, parietal, and occipital WMH volume was assessed, adjusting for baseline WMH volume. Result: The annual rate of change in frontal WMH was not significantly different by diagnosis. The annual rate of change in temporal (0.7 [0.4, 1.1], p<0.001) and in occipital WMH (1.6 [0.7, 2.5], p=0.0008) was faster in the group that remained AD at both timepoints compared to the group that remained Cognitively‐Stable at both timepoints. The annual rate of change in parietal WMH was greater in the group that progressed from MCI‐DS to AD (0.6 [0.1, 1.0], p=0.02) and in the group that remained AD at both timepoints (1.1 [0.6, 1.7], p=0.0002) compared to the group that remained Cognitively‐Stable at both timepoints. Conclusion: In adults with DS, parietal WMH accumulates fastest in those that progress to or have a diagnosis of AD, while temporal and occipital WMH accumulate fastest in those with a diagnosis of AD. Posteriorly distributed WMH may have specificity for AD progression in adults with DS with implications for anti‐amyloid therapeutics that have cerebrovascular side effects.Item The prevalence of tau‐PET positivity in aging and dementia(Wiley, 2025-01-09) Coomans, Emma M.; Groot, Colin; Rowe, Christopher C.; Dore, Vincent; Villemagne, Victor L.; van de Giessen, Elsmarieke; van der Flier, Wiesje M.; Pijnenburg, Yolande A. L.; Visser, Pieter Jelle; den Braber, Anouk; Pontecorvo, Michael; Shcherbinin, Sergey; Kennedy, Ian A.; Jagust, William J.; Baker, Suzanne L.; Harrison, Theresa M.; Gispert, Juan Domingo; Shekari, Mahnaz; Minguillon, Carolina; Smith, Ruben; Mattsson-Carlgren, Niklas; Palmqvist, Sebastian; Strandberg, Olof; Stomrud, Erik; Malpetti, Maura; O'Brien, John T.; Rowe, James B.; Jäger, Elena; Bischof, Gérard N.; Drzezga, Alexander; Garibotto, Valentina; Frisoni, Giovanni; Peretti, Débora Elisa; Schöll, Michael; Skoog, Ingmar; Kern, Silke; Sperling, Reisa A.; Johnson, Keith A.; Risacher, Shannon L.; Saykin, Andrew J.; Carrillo, Maria C.; Dickerson, Brad C.; Apostolova, Liana G.; Barthel, Henryk; Rullmann, Michael; Messerschmidt, Konstantin; Vandenberghe, Rik; Van Laere, Koen; Spruyt, Laure; Franzmeier, Nicolai; Brendel, Matthias; Gnörich, Johannes; Benzinger, Tammie L. S.; Lagarde, Julien; Sarazin, Marie; Bottlaender, Michel; Villeneuve, Sylvia; Poirier, Judes; Seo, Sang Won; Gu, Yuna; Kim, Jun Pyo; Mormino, Elizabeth; Young, Christina B.; Vossler, Hillary; Rosa-Neto, Pedro; Therriault, Joseph; Rahmouni, Nesrine; Coath, William; Cash, David M.; Schott, Jonathan M.; Rabinovici, Gil D.; La Joie, Renaud; Rosen, Howard J.; Johnson, Sterling C.; Christian, Bradley T.; Betthauser, Tobey J.; Hansson, Oskar; Ossenkoppele, Rik; Radiology and Imaging Sciences, School of MedicineBackground Tau‐PET imaging allows in‐vivo detection of neurofibrillary tangles. One tau‐PET tracer (i.e., [18F]flortaucipir) has received FDA‐approval for clinical use, and multiple other tau‐PET tracers have been implemented into clinical trials for participant selection and/or as a primary or secondary outcome measure. To optimize future use of tau‐PET, it is essential to understand how demographic, clinical and genetic factors affect tau‐PET‐positivity rates. Method This large‐scale multi‐center study includes 9713 participants from 35 cohorts worldwide who underwent tau‐PET with [18F]flortaucipir (n = 6420), [18F]RO948 (n = 1999), [18F]MK6240 (n = 878) or [18F]PI2620 (n = 416) (Table‐1). We analyzed individual‐level tau‐PET SUVR data using a cerebellar reference region that were processed either centrally (n = 3855) or by each cohort (n = 5858). We computed cohort‐specific SUVR thresholds based on the mean + 2 standard deviations in a temporal meta‐region of amyloid‐negative cognitively normal (CN) individuals aged >50. Logistic generalized estimating equations were used to estimate tau‐PET‐positivity probabilities, using an exchangeable correlation structure to account for within‐cohort correlations. Analyses were performed with (interactions between) age, amyloid‐status, and APOE‐e4 carriership as independent variables, stratified for syndrome diagnosis. Result The study included 5962 CN participants (7.5% tau‐PET‐positive), 1683 participants with mild cognitive impairment (MCI, 33.8% tau‐PET‐positive) and 2068 participants with a clinical diagnosis of dementia (62.1% tau‐PET‐positive) (Figure‐1). From age 60 to 80 years, the estimated prevalence of tau‐PET‐positivity increased from 1.2% [95% CI: 0.9%‐1.5%] to 3.7% [2.3%‐5.1%] among CN amyloid‐negative participants; and from 16.4% [10.8%‐22.1%] to 20.5% [18.8%‐22.2%] among CN amyloid‐positive participants. Among amyloid‐negative participants with MCI and dementia, from age 60 to 80 years, the estimated prevalence of tau‐PET‐positivity increased from 3.5% [1.6%‐5.3%] to 11.8% [7.1%‐16.5%] and from 12.6% [4.5%‐20.7%] to 15.9% [6.7%‐25.1%] respectively. In contrast, among amyloid‐positive participants with MCI and dementia, from age 60 to 80 years, the estimated prevalence of tau‐PET‐positivity decreased from 66.5% [57.0%‐76.0%] to 48.3% [42.9%‐53.8%] and from 92.3% [88.7%‐95.9%] to 73.4% [67.5%‐79.3%] respectively. APOE‐e4 status primarily modulated the association of age with tau‐PET‐positivity estimates among CN and MCI amyloid‐positive participants (Figure‐2). Conclusion This large‐scale multi‐cohort study provides robust prevalence estimates of tau‐PET‐positivity, which can aid the interpretation of tau‐PET in the clinic and inform clinical trial designs.