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AbstractBackgroundThe Standardized Centralized Alzheimer’s & related dementias Neuroimaging (SCAN) project harmonizes processing of prospectively acquired PET and MRI scans from Alzheimer’s disease research centers (ADRCs) across the USA. SCAN data will be integrated with other ADRC data streams within the National Alzheimer’s Coordinating Center (NACC), including the Uniform Data Set which includes rich longitudinal demographic, cognitive, and neuropathological data, resulting in a large, potentially representative cohort. The project has sought to accommodate site‐to‐site variation in image acquisition while permitting harmonization of imaging data, necessitating new analytic approaches for different PET tracers and PET scans without MRIs.MethodPET scans underwent preprocessing for quality control and smoothing to a uniform resolution. MRI‐free processing pipelines and positivity thresholds were developed for each beta‐amyloid (Aβ)‐PET tracer: [11C]PiB, [18F]florbetaben (FBB), [18F]florbetapir (FBP) and [18F]flutafuranol (NAV). A generic Aβ‐PET template was used for spatial normalization and cortical summary SUVRs were calculated in template space. Aβ‐positivity thresholds were determined by examining both MRI‐dependent thresholds transformed into MRI‐free units and a young control mean+2SD. Centiloid (CL) conversions were completed for each Aβ‐PET tracer. Tau‐PET tracers ([18F]flortaucipir (FTP) and [18F]MK‐6240) required tracer‐specific warping templates for best performance relative to gold‐standard MRI‐dependent processing. Demographic and clinical data were obtained from NACC.Result15 ADRCs have contributed data to SCAN as of January 2023. 477 participants had preprocessed, SCAN‐compliant (https://scan.naccdata.org/) Aβ‐PET scans and NACC data; 219 of these participants (46%) also had tau‐PET scans (Table 1). This cohort included 18% of individuals from underrepresented groups. Clinical diagnostic groups ranged from cognitively unimpaired to MCI and dementia (74% of whom had AD dementia). Using pooled Aβ‐PET data across 4 tracers in CLs, there were expected differences in Aβ burden by diagnosis group (Fig. 1) and positive associations with tau (Fig. 2).ConclusionSCAN has successfully harmonized PET data from more than a dozen US ADRCs yielding a large, clinically heterogeneous cohort of deeply phenotyped research participants. SCAN data will be compatible with ADNI data allowing for further pooling of data and greater statistical power to drive critical questions in AD and related dementias research.

AbstractBackgroundThe U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) is a 2‐year randomized controlled trial to evaluate the effect of lifestyle interventions in cognitively unimpaired older adults (60‐79 years) at risk for decline/dementia. Here, using data from the POINTER Imaging ancillary substudy, we explore how Alzheimer’s disease pathology and cardiovascular risk influence brain structure, cognition and their relationship.MethodPOINTER Imaging participants underwent cross‐sectional MRI, [18F]Florbetaben (FBB) Aβ‐PET and [18F]MK6240 tau‐PET. FBB and MK6240 data were processed using previously validated methods. MRIs were processed with voxel‐based morphometry. To quantify cardiovascular risk, the Framingham risk score (FRS) was calculated for each participant. We used linear regression models in the whole sample as well as in Aβ status subgroups to evaluate voxel‐wise associations of brain structure, measured using voxel‐based morphometry, with age, FRS, AD pathology (cortical summary Aβ and entorhinal cortex (ERC) tau burden), and a global cognition composite score.ResultAcross all 624 participants (Table 1), cognition (age‐adjusted) was positively related to brain structure across temporal, frontal and medial parietal cortices (Fig. 1A). ERC tau‐PET was negatively associated with brain structure in bilateral medial temporal lobes (MTL) and, notably, in bilateral basal forebrain (Fig. 1B). FRS showed significant negative associations in superior temporal gyrus and occipital cortex (Fig. 1C), but tau‐PET associations remained similar when adjusting for FRS. In Aβ+ participants, cognition‐ and FRS‐structure relationships were weaker but tau‐PET‐structure associations were stronger and extended outside the MTL. In Aβ‐ participants, cognition‐ and FRS‐structure relationships were similar to those observed in the whole cohort and tau‐PET associations were no longer significant.ConclusionIn this heterogeneous cohort of older adults, tau was associated with brain structure in strikingly specific patterns that were related to Aβ but not to cardiovascular risk as measured by the FRS. Tau‐structure associations were restricted to temporal lobes and basal forebrain and were independent of more widespread cognition‐structure associations, indicating that factors other than tau may play a critical role. Our next steps include comparing the current cohort to others with different at‐risk characteristics (e.g., ADNI, Berkeley Aging Cohort Study).

AbstractBackgroundA key focus of the U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) is recruitment of unimpaired older individuals at risk for cognitive decline with heterogeneous characteristics (under‐represented racial and ethnicity groups (URG), family history of cognitive decline, hypertension, geographic diversity), and a subset of individuals undergo PET and MRI.MethodTo examine effects of heterogeneity on relationships between risk factors, AD biomarkers (Aß and entorhinal tau PET, hippocampal volume (HV)) and cognition (global, executive function, and memory) were examined from U.S. POINTER neuroimaging participants (N = 602, about 65% of the anticipated total sample) and a subset of Alzheimer’s Disease Neuroimaging Initiative participants (N = 503). Neuroimaging data were processed and analyzed using harmonized methods across studies. Some cohort‐specific measurements were standardized using a within‐cohort reference group (Aß‐negative individuals <70yrs and with global CDR = 0).ResultU.S. POINTER imaging participants are younger than those in ADNI (68.6+/‐5.0yrs vs 70.7+/‐4.4yrs), more likely to be female (65% vs 58%) and from URG (27% vs 15%), and had lower education (14.7+/‐3.3yrs vs 16.7+/‐2.3yrs) and higher Framingham Cardiovascular Risk scores (9.9+/‐8.3 vs 7.7+/‐5.3). The groups differed on several AD biomarkers and cognitive measures (Table). In regression models, AD biomarkers were stronger predictors of cognitive performance in ADNI compared to POINTER. Specifically, Aß+ individuals with elevated tau had disproportionately poorer cognitive performance in ADNI, and this relationship remained consistent across cognitive measures (Figure). Conversely, demographic/risk variables were stronger predictors in POINTER. Demographic/risk predictors (age, sex, education, race, and FRS) together explained twice as much variance in global cognition in POINTER compared to ADNI (Adjusted R2 = 29% vs 14%). The addition of AD biomarkers to the model further increased the amount of variance in global cognition explained from 14% to 34% in ADNI, but addition of AD biomarkers did not increase variance explained in the POINTER model.ConclusionHeterogeneity among study participants appears to influence baseline biomarker‐cognition relationships such that AD biomarkers explain more variability in cognitive performance in ADNI than POINTER. These findings further suggest that cohort characteristics may affect the potential influence of amyloid‐ and tau‐modifying treatments on cognition.

AbstractBackgroundThe Standardized Centralized Alzheimer’s & related dementias Neuroimaging (SCAN) project harmonizes processing of prospectively acquired PET and MRI scans from Alzheimer’s disease research centers (ADRCs) across the USA. SCAN data will be integrated with other ADRC data streams within the National Alzheimer’s Coordinating Center (NACC), including the Uniform Data Set which includes rich longitudinal demographic, cognitive, and neuropathological data, resulting in a large, potentially representative cohort. The project has sought to accommodate site‐to‐site variation in image acquisition while permitting harmonization of imaging data, necessitating new analytic approaches for different PET tracers and PET scans without MRIs.MethodPET scans underwent preprocessing for quality control and smoothing to a uniform resolution. MRI‐free processing pipelines and positivity thresholds were developed for each beta‐amyloid (Aß)‐PET tracer: [11C]PiB, [18F]florbetaben (FBB), [18F]florbetapir (FBP) and [18F]flutafuranol (NAV). A generic Aß‐PET template was used for spatial normalization and cortical summary SUVRs were calculated in template space. Aß‐positivity thresholds were determined by examining both MRI‐dependent thresholds transformed into MRI‐free units and a young control mean+2SD. Centiloid (CL) conversions were completed for each Aß‐PET tracer. Tau‐PET tracers ([18F]flortaucipir (FTP) and [18F]MK‐6240) required tracer‐specific warping templates for best performance relative to gold‐standard MRI‐dependent processing. Demographic and clinical data were obtained from NACC.Result15 ADRCs have contributed data to SCAN as of January 2023. 477 participants had preprocessed, SCAN‐compliant (https://scan.naccdata.org/) Aß‐PET scans and NACC data; 219 of these participants (46%) also had tau‐PET scans (Table 1). This cohort included 18% of individuals from underrepresented groups. Clinical diagnostic groups ranged from cognitively unimpaired to MCI and dementia (74% of whom had AD dementia). Using pooled Aß‐PET data across 4 tracers in CLs, there were expected differences in Aß burden by diagnosis group (Fig. 1) and positive associations with tau (Fig. 2).ConclusionSCAN has successfully harmonized PET data from more than a dozen US ADRCs yielding a large, clinically heterogeneous cohort of deeply phenotyped research participants. SCAN data will be compatible with ADNI data allowing for further pooling of data and greater statistical power to drive critical questions in AD and related dementias research.

Abstract Lucid episodes (LE) occur in people living with dementia who have seemingly lost cognitive capacity. Understanding LEs is a relatively new area of scientific inquiry. Most LE studies have utilized different conceptual and operational definitions. Reaching a definition of LE is critical foundation to facilitate more systematic investigation and new knowledge of LEs. The goal of this study was to convene a group of 13 clinical experts to brainstorm on the key components needed to understand LE among people living with dementia (PLWD). We aimed to reach consensus from the group on (1) potential medical or clinical explanations for LEs; (2) necessary medical and clinical questions to understand LE; (3) interpretation of the presence of LE. Thirteen experts from different disciplines (neurology, psychiatry, psychology, pharmacy, palliative care, hospice, nursing, social work, primary care, geriatrics, and professional home caregivers) participated in a virtual Delphi Method study. Experts provided a range of opinions on potential medical and clinical explanations for LE, necessary questions to understand LE, and did not reach consensus on the presence of LE when presented with clinical vignettes. Panelists highlighted key medical and contextual factors as well as a need to know more information about the general demeanor and typical behavior of the PLWD to make a definitive judgement about whether LE occurred. Clinical consensus on LEs is complex. There is great variability in how behaviors and cognitive fluctuations in PLWD are appraised by clinical experts.

Abstract Lucid episodes (LE) in people living with late-stages of dementia (PLWD) have been reported anecdotally, but less is known about how this seemingly unexpected phenomenon is experienced by family members. This study aims to examine variability in family caregivers’ experiences with LE, focusing on the two most common groups of informal caregivers, spouses and children—whether they may exhibit differential appraisals of and responses to LEs. Using a sample of former and current family caregivers from UsAgainstAlzheimer’s A-LIST, we conducted an online survey to spouse and child caregivers (N = 387). Qualitative semi-structured interviews were also conducted with a subset of these caregivers who have witnessed an LE (n = 22). Survey results indicate that child caregivers were more likely to witness a LE. Among “former” caregivers who have witnessed a LE (n = 140), spouses were likely to appraise LEs more negatively and make changes in care decisions (i.e., end-of-life planning and financial decisions) after LE, compared to child caregivers. Among “current” caregivers who have witnessed a LE (n = 80), spouses were more likely to indicate no special circumstances prior to LE, whereas children were more likely to indicate LEs associated with visits from friends and family; there was no difference in positive and negative appraisals of LE between current spouse and child caregivers. Content analysis of qualitative interviews revealed that observed differences between spouses and children were related to their different caregiving contexts, such as relationship history, living arrangement, expectations/motivation, and care resources.

PURPOSE: This study aimed to analyze organ system-based causes and non-organ system-based mechanisms of death (COD, MOD) in people with myelomeningocele (MMC), comparing urological to other COD. METHODS: A retrospective review was performed of 16 institutions in Canada/United States of non-random convenience sample of people with MMC (born > = 1972) using non-parametric statistics. RESULTS: Of 293 deaths (89% shunted hydrocephalus), 12% occurred in infancy, 35% in childhood, and 53% in adulthood (documented COD: 74%). For 261 shunted individuals, leading COD were neurological (21%) and pulmonary (17%), and leading MOD were infections (34%, including shunt infections: 4%) and non-infectious shunt malfunctions (14%). For 32 unshunted individuals, leading COD were pulmonary (34%) and cardiovascular (13%), and leading MOD were infections (38%) and non-infectious pulmonary (16%). COD and MOD varied by shunt status and age (p < = 0.04), not ambulation or birthyear (p > = 0.16). Urology-related deaths (urosepsis, renal failure, hematuria, bladder perforation/cancer: 10%) were more likely in females (p = 0.01), independent of age, shunt, or ambulatory status (p > = 0.40). COD/MOD were independent of bladder augmentation (p = >0.11). Unexplained deaths while asleep (4%) were independent of age, shunt status, and epilepsy (p >= 0.47). CONCLUSION: COD varied by shunt status. Leading MOD were infectious. Urology-related deaths (10%) were independent of shunt status; 26% of COD were unknown. Life-long multidisciplinary care and accurate mortality documentation are needed.

Abstract Background Vaccine preventable infections (VPIs) are a significant cause of hospitalizations and morbidity and mortality for pediatric solid organ transplant (SOT) recipients. In this single-center study, we assessed up-to-date (UTD) status of routine childhood immunizations among our institution’s pediatric SOT recipients. Methods We collected immunization data on all pediatric patients who underwent liver, kidney, or heart transplants between January 1, 2011 and December 31, 2021 at Mayo Clinic, Rochester, MN by retrospectively reviewing electronic medical record data. We also assessed whether patients were evaluated by a pediatric infectious diseases (PID) specialist within 1 year of transplant. Immunization status was determined using the CDC child and adolescent immunization schedule, excluding seasonal influenza and SARS-CoV-2 immunizations. Results A total of 143 patients were included in our study (n = 45 liver, 54 kidney, 44 heart recipients); 49.7% were male. At the time of transplant, 39 patients were considered UTD (27.3% [Figure 1]). There was no difference by organ type (p = 0.59) and whether patients had seen PID prior to transplant (p = 0.17). Excluding live viral vaccinations, 45 patients were UTD (31.5%). Human papillomavirus was the least UTD vaccine series (Figure 2). Most patients were not UTD in just one or two series (Figure 1). A significant difference in UTD status was found based on age at transplant (p = 0.03), with younger patients having higher rates of UTD status (mean age 7.1 [SD 5.75] vs 9.9 [SD 5.92] years).Figure 1.Vaccination status of pediatric SOT recipients at time of transplant and number of incomplete series.Figure 2.Vaccination status by series for eligible pediatric SOT recipients. Conclusion To date, this study is the largest cohort of pediatric SOT recipients of three organ types assessing routine childhood vaccination status. In this single-center cohort spanning 11 years, we found that less than a third of patients were UTD on routine childhood immunizations at the time of transplant. While some immunizations can be given post-transplant, every effort should be made to update vaccines among transplant candidates to optimize efficacy and protection, thereby reducing the consequences of VPIs within this vulnerable population. Further studies are needed to address reasons for under-immunization and develop strategies to improve vaccination rates. Disclosures All Authors: No reported disclosures