Association of Systemic Lupus Erythematosus Disease Activity With Choroidal Thickness.

OBJECTIVE: To determine the association between disease activity and choroidal thickness in patients with systemic lupus erythematosus (SLE). METHODS: We conducted a cohort study of 24 SLE patients and 13 healthy controls recruited at Washington University School of Medicine between June 2019 and November 2021. SLE disease activity was assessed using the SLE Disease Activity Index-2000 Responder Index-50 (S2K RI-50). Patients were divided into four groups: high disease activity/no lupus nephritis (HDA/no LN; S2K RI-50 > 4), HDA/active LN (HDA/active LN; S2K RI-50 > 4), low disease activity/inactive LN (LDA/inactive LN; S2K RI-50 ≤ 4), and LDA/no LN (LDA/no LN; S2K RI-50 ≤ 4). LDA/no LN patients were age-, sex-, and race-matched to healthy controls and patients in other SLE groups. Choroidal thickness of the right eye was measured blinded to disease activity on a horizontal section through the fovea on optical coherence tomography images taken within a week of disease assessment. RESULTS: Patients with HDA had choroidal thickening compared with matched patients with LDA. After controlling for multiplicity, choroidal thinning remained statistically significant at 1000 µm nasal to the fovea (308 ± 68 vs 228 ± 64 µm, p = 0.001). Choroidal thickness was not different between LDA/no LN and LDA/inactive LN or healthy controls. CONCLUSION: HDA in patient with SLE is associated with increased choroidal thickness whereas comorbid inactive LN did not affect choroidal thickness. Additional studies in a larger longitudinal cohort are needed to study whether choroidal thickness may be used as a noninvasive, adjunctive measure for disease activity in SLE.

Assessing deviations for HPCs obtained during COVID-19 (ADHOC): Evaluating impact of the COVID-19 pandemic on cellular therapy products and processes, the BEST collaborative study.

BACKGROUND: The success of allogeneic hematopoietic stem cell transplantation is dependent on a world-wide network of collection centers providing donations that predominantly have been infused as fresh cells. The logistics chain that supports the just-in-time delivery model for stem cell and immunotherapy products was severely stressed by the COVID pandemic, and in early 2020 a number of national and international bodies recommended that cells should be cryopreserved at the collection or transplant center to avoid interruptions in their acquisition or delivery to patients who had started conditioning. STUDY DESIGN: To assess the potential consequences of such pandemic-related deviations to normal practice, we surveyed nine international laboratories to determine if the characteristics or transplant outcomes of allogeneic stem cell donations differed in the immediate periods before and after the switch to routine cryopreservation. RESULTS: Nine centers on two continents provided data for 72 HSC donations just before, and 71 just after, switching to cryopreservation for allogeneic HSC products. No statistically significant differences between the period before and after cryopreservation were noted for time from product collection to receipt, product temperature at receipt, or CD34+ cell viability at receipt. There was an indication of slower absolute neutrophil count recovery after cryopreservation was required (mean time of 15 vs. 17.6 days). DISCUSSION: While there were no apparent changes to most parameters studied, there was an indication of slower neutrophil engraftment that will need to be examined in larger, longer term studies.

Preclinical Alzheimer's disease biomarkers accurately predict cognitive and neuropathological outcomes.

Alzheimer's disease biomarkers are widely accepted as surrogate markers of underlying neuropathological changes. However, few studies have evaluated whether preclinical Alzheimer's disease biomarkers predict Alzheimer's neuropathology at autopsy. We sought to determine whether amyloid PET imaging or CSF biomarkers accurately predict cognitive outcomes and Alzheimer's disease neuropathological findings. This study included 720 participants, 42-91 years of age, who were enrolled in longitudinal studies of memory and aging in the Washington University Knight Alzheimer Disease Research Center and were cognitively normal at baseline, underwent amyloid PET imaging and/or CSF collection within 1 year of baseline clinical assessment, and had subsequent clinical follow-up. Cognitive status was assessed longitudinally by Clinical Dementia Rating®. Biomarker status was assessed using predefined cut-offs for amyloid PET imaging or CSF p-tau181/amyloid-ß42. Subsequently, 57 participants died and underwent neuropathologic examination. Alzheimer's disease neuropathological changes were assessed using standard criteria. We assessed the predictive value of Alzheimer's disease biomarker status on progression to cognitive impairment and for presence of Alzheimer's disease neuropathological changes. Among cognitively normal participants with positive biomarkers, 34.4% developed cognitive impairment (Clinical Dementia Rating > 0) as compared to 8.4% of those with negative biomarkers. Cox proportional hazards modelling indicated that preclinical Alzheimer's disease biomarker status, APOE ɛ4 carrier status, polygenic risk score and centred age influenced risk of developing cognitive impairment. Among autopsied participants, 90.9% of biomarker-positive participants and 8.6% of biomarker-negative participants had Alzheimer's disease neuropathological changes. Sensitivity was 87.0%, specificity 94.1%, positive predictive value 90.9% and negative predictive value 91.4% for detection of Alzheimer's disease neuropathological changes by preclinical biomarkers. Single CSF and amyloid PET baseline biomarkers were also predictive of Alzheimer's disease neuropathological changes, as well as Thal phase and Braak stage of pathology at autopsy. Biomarker-negative participants who developed cognitive impairment were more likely to exhibit non-Alzheimer's disease pathology at autopsy. The detection of preclinical Alzheimer's disease biomarkers is strongly predictive of future cognitive impairment and accurately predicts presence of Alzheimer's disease neuropathology at autopsy.

Autosomal dominant and sporadic late onset Alzheimer's disease share a common in vivo pathophysiology.

The extent to which the pathophysiology of autosomal dominant Alzheimer's disease corresponds to the pathophysiology of 'sporadic' late onset Alzheimer's disease is unknown, thus limiting the extrapolation of study findings and clinical trial results in autosomal dominant Alzheimer's disease to late onset Alzheimer's disease. We compared brain MRI and amyloid PET data, as well as CSF concentrations of amyloid-ß42, amyloid-ß40, tau and tau phosphorylated at position 181, in 292 carriers of pathogenic variants for Alzheimer's disease from the Dominantly Inherited Alzheimer Network, with corresponding data from 559 participants from the Alzheimer's Disease Neuroimaging Initiative. Imaging data and CSF samples were reprocessed as appropriate to guarantee uniform pipelines and assays. Data analyses yielded rates of change before and after symptomatic onset of Alzheimer's disease, allowing the alignment of the ∼30-year age difference between the cohorts on a clinically meaningful anchor point, namely the participant age at symptomatic onset. Biomarker profiles were similar for both autosomal dominant Alzheimer's disease and late onset Alzheimer's disease. Both groups demonstrated accelerated rates of decline in cognitive performance and in regional brain volume loss after symptomatic onset. Although amyloid burden accumulation as determined by PET was greater after symptomatic onset in autosomal dominant Alzheimer's disease than in late onset Alzheimer's disease participants, CSF assays of amyloid-ß42, amyloid-ß40, tau and p-tau181 were largely overlapping in both groups. Rates of change in cognitive performance and hippocampal volume loss after symptomatic onset were more aggressive for autosomal dominant Alzheimer's disease participants. These findings suggest a similar pathophysiology of autosomal dominant Alzheimer's disease and late onset Alzheimer's disease, supporting a shared pathobiological construct.

IL-33 signaling in sensory neurons promotes dry skin itch.

BACKGROUND: Chronic pruritus, or itch, is common and debilitating, but the neuroimmune mechanisms that drive chronic itch are only starting to be elucidated. Recent studies demonstrate that the IL-33 receptor (IL-33R) is expressed by sensory neurons. However, whether sensory neuron-restricted activity of IL-33 is necessary for chronic itch remains poorly understood. OBJECTIVES: We sought to determine if IL-33 signaling in sensory neurons is critical for the development of chronic itch in 2 divergent pruritic disease models. METHODS: Plasma levels of IL-33 were assessed in patients with atopic dermatitis (AD) and chronic pruritus of unknown origin (CPUO). Mice were generated to conditionally delete IL-33R from sensory neurons. The contribution of neuronal IL-33R signaling to chronic itch development was tested in mouse models that recapitulate key pathologic features of AD and CPUO, respectively. RESULTS: IL-33 was elevated in both AD and CPUO as well as their respective mouse models. While neuron-restricted IL-33R signaling was dispensable for itch in AD-like disease, it was required for the development of dry skin itch in a mouse model that mirrors key aspects of CPUO pathology. CONCLUSIONS: These data highlight how IL-33 may be a predominant mediator of itch in certain contexts, depending on the tissue microenvironment. Further, this study provides insight into future therapeutic strategies targeting the IL-33 pathway for chronic itch.

Cross-sectional and longitudinal comparisons of biomarkers and cognition among asymptomatic middle-aged individuals with a parental history of either autosomal dominant or late-onset Alzheimer's disease.

BACKGROUND: Comparisons of late-onset Alzheimer's disease (LOAD) and autosomal dominant AD (ADAD) are confounded by age. METHODS: We compared biomarkers from cerebrospinal fluid (CSF), magnetic resonance imaging, and amyloid imaging with Pittsburgh Compound-B (PiB) across four groups of 387 cognitively normal participants, 42 to 65 years of age, in the Dominantly Inherited Alzheimer Network (DIAN) and the Adult Children Study (ACS) of LOAD: DIAN mutation carriers (MCs) and non-carriers (NON-MCs), and ACS participants with a positive (FH+) and negative (FH-) family history of LOAD. RESULTS: At baseline, MCs had the lowest age-adjusted level of CSF Aß42 and the highest levels of total and phosphorylated tau-181, and PiB uptake. Longitudinally, MC had similar increase in PiB uptake to FH+, but drastically faster decline in hippocampal volume than others, and was the only group showing cognitive decline. DISCUSSION: Preclinical ADAD and LOAD share many biomarker signatures, but cross-sectional and longitudinal differences may exist.

Socioeconomic Status Mediates Racial Differences Seen Using the AT(N) Framework.

OBJECTIVES: African Americans are at greater risk for developing Alzheimer's disease (AD) dementia than non-Hispanic whites. In addition to biological considerations (eg, genetic influences and comorbid disorders), social and environmental factors may increase the risk of AD dementia. This paper (1) assesses neuroimaging biomarkers of amyloid (A), tau (T), and neurodegeneration (N) for potential racial differences and (2) considers mediating effects of socioeconomic status (SES) and measures of small vessel and cardiovascular disease on observed race differences. METHODS: Imaging measures of AT(N) (amyloid and tau positron emission tomography [PET]) structural magnetic resonance imaging (MRI), and resting state functional connectivity (rs-fc) were collected from African American (n = 131) and white (n = 685) cognitively normal participants age 45 years and older. Measures of small vessel and cardiovascular disease (white matter hyperintensities [WMHs] on MRI, blood pressure, and body mass index [BMI]) and area-based SES were included in mediation analyses. RESULTS: Compared to white participants, African American participants had greater neurodegeneration, as measured by decreased cortical volumes (Cohen's f2 = 0.05, p < 0.001). SES mediated the relationship between race and cortical volumes. There were no significant race effects for amyloid, tau, or rs-fc signature. INTERPRETATION: Modifiable factors, such as differences in social contexts and resources, particularly area-level SES, may contribute to observed racial differences in AD. Future studies should emphasize collection of relevant psychosocial factors in addition to the development of intentional diversity and inclusion efforts to improve the racial/ethnic and socioeconomic representativeness of AD studies. ANN NEUROL 2021;89:254-265.

Perceptions of Research Burden and Retention Among Participants in ADRC Cohorts.

OBJECTIVES: Alzheimer disease (AD) and related dementias clinical research is associated with significant participant burden. The Perceived Research Burden Assessment (PeRBA) measures participants' perceptions of logistical, psychological, and physical burdens. The purpose of this study was to assess PeRBA's psychometric properties, perceptual sources, and behavioral consequences with participants in a multisite study of participant retention in longitudinal cohort studies of Alzheimer disease and related dementias. DESIGN: Multicenter mixed methods. SETTING: In-person or phone. PARTICIPANTS: A total of 443 participants at 4 NIA-funded Alzheimer Disease Research Centers (ADRCs) were randomly selected and invited to participate if they were 45 years of age or more, enrolled in longitudinal studies, and had a Clinical Dementia Rating Scale global score ≤1. MEASUREMENTS: Participants completed a 20-minute survey including the 21-item PeRBA about their research participation. RESULTS: PeRBA demonstrated high-internal consistency and convergent validity. PeRBA scores correlated with expected perceptual factors. Higher PeRBA scores were associated with lower attendance and higher dropout rates. CONCLUSIONS: PeRBA can be used by researchers to identify participants who may feel overburdened and tailor approaches and strategies to support participants in longitudinal AD studies, maximizing participation, and reducing dropout. Making efforts to increase participants' understanding of study procedures, and building and maintaining trust throughout the study, can contribute to reducing perceived burden and potentially increasing retention in longitudinal AD studies.

Inclusion of Thyroid Nodule Location in American College of Radiology TI-RADS Scoring: Impact on System Performance.

Emerging data suggest that the location of thyroid nodules influences malignancy risk. The purpose of this study was to explore the impact of including location in American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) scoring. Four of five revised scoring algorithms that added 1 or 2 points to higher-risk locations were associated with lowered accuracy due to lower specificity. However, an algorithm that added 1 point to isthmic nodules did not differ significantly from ACR TI-RADS in accuracy; one additional isthmic cancer was diagnosed for each 10.3 additional benign nodules recommended for biopsy.

Comparative Performance and Neuropathologic Validation of the AD8 Dementia Screening Instrument.

BACKGROUND/OBJECTIVE: The AD8 informant-based screening instrument has been validated with molecular biomarkers of Alzheimer disease (AD) but not with the gold standard of neuropathologic AD. The objective of this study was to validate the AD8 with neuropathologic AD and compare its predictive performance with that of the Mini-Mental State Examination and both participant-derived and informant-derived subjective memory complaint (SMC) regarding the participant. METHODS: This longitudinal cohort study at the Knight Alzheimer Disease Research Center at Washington University included 230 participants, ages 50 to 91 years, who later had a neuropathologic examination. Four dementia screening instruments from their baseline assessment were evaluated: the AD8, Mini-Mental State Examination, participant SMC, and informant SMC. The primary outcome was a neuropathologic diagnosis of AD. RESULTS: The average participant age at baseline was 80.4 years, 48% were female. All 4 dementia screening tests were predictive of neuropathologic AD. There was no significant difference in the predictive performance of the AD8 compared with the other instruments, but the AD8 had superior sensitivity and combined positive and negative predictive values. CONCLUSION: The AD8 is a brief and sensitive screening instrument that may facilitate earlier and more accurate AD diagnosis in a variety of care settings.

Complex interactions underlie racial disparity in the risk of developing Alzheimer's disease dementia.

INTRODUCTION: We aim to determine racial disparities and their modifying factors in risk for Alzheimer's disease (AD) dementia among cognitively normal individuals 65 years or older. METHODS: Longitudinal data from the National Alzheimer's Coordinating Center Uniform Data Set on 1229 African Americans (AAs) and 6679 whites were analyzed for the risk of AD using competing risk models with death as a competing event. RESULTS: Major AD risk factors modified racial differences which, when statistically significant, occurred only with older age among APOE ε4 negative individuals, but also with younger age among APOE ε4 positive individuals. The racial differences favored AAs among individuals with body mass index (BMI) < 30, but whites among individuals with a high BMI (≥ 30), and were additionally modified by sex, education, hypertension, and smoking status. CONCLUSIONS: The presence, direction, and relative magnitude of racial disparity for AD represent an interactive function of major AD and cerebrovascular risk factors.

Examining the Complicated Relationship Between Depressive Symptoms and Cognitive Impairment in Preclinical Alzheimer Disease.

INTRODUCTION: The relationships between Alzheimer disease (AD), cognitive performance, and depression are poorly understood. It is unclear whether depressive features are a prodrome of AD. In addition, some studies of aging exclude depressed individuals, which may inappropriately limit generalizability. The aim of the present study was to determine whether depressive symptoms affect cognitive function in the context of preclinical AD. METHODS: Cross-sectional multivariate analysis of participants in a longitudinal study of aging (n=356) that evaluates the influence of depressive symptoms on cognitive function in cognitively normal adults. RESULTS: There is no relationship between the presence of depressive symptoms and cognitive function in those with either no evidence of preclinical AD or biomarker evidence of early-stage preclinical AD. However, in later stages of preclinical AD, the presence of depressive symptoms demonstrated interactive effects, including in episodic memory (0.96; 95% confidence interval, 0.31-1.62) and global cognitive function (0.46; 95% confidence interval, 0.028-0.89). CONCLUSIONS: The presence of depressive symptoms may be a late prodrome of AD. In addition, studies investigating cognitive function in older adults may not need to exclude participants with depressive symptomology, but may still consider depressive symptoms as a potential confounder in the context of more extensive neuronal injury.

Staging biomarkers in preclinical autosomal dominant Alzheimer's disease by estimated years to symptom onset.

INTRODUCTION: Staging preclinical Alzheimer disease (AD) by the expected years to symptom onset (EYO) in autosomal dominant AD (ADAD) through biomarker correlations is important. METHODS: We estimated the correlation matrix between EYO/cognition and imaging/CSF biomarkers, and searched for the EYO cutoff where a change in the correlations occurred before and after the cutoff among the asymptomatic mutation carriers of ADAD. We then estimated the longitudinal rate of change for biomarkers/cognition within each preclinical stage defined by the EYO. RESULTS: Based on the change in the correlations, the preclinical ADAD was divided by EYOs -7 and -13 years. Mutation carriers demonstrated a temporal ordering of biomarker/cognition changes across the three preclinical stages. DISCUSSION: Duration of each preclinical stage can be estimated in ADAD, facilitating better planning of prevention trials with the EYO cutoffs under the recently released FDA guidance. The generalization of these results to sporadic AD warrants further investigation.

Retention of Study Partners in Longitudinal Studies of Alzheimer Disease.

BACKGROUND: Study partners are required for all participants at Alzheimer's Disease Research Centers (ADRCs). Study partners' attitudes and beliefs may contribute to missed visits and negatively impact retention of participants in longitudinal AD studies. OBJECTIVE: Study partners (N = 212) of participants (Clinical Dementia Rating® [CDR]≤2) at four ADRCs were randomly surveyed to examine their facilitators and barriers to continued participation in AD studies. METHODS: Reasons for participation were analyzed with factor analysis and regression analysis. Effects of complaints and goal fulfillment on attendance were estimated with fractional logistic models. Open-ended responses were characterized with a Latent Dirichlet Allocation topic model. RESULTS: Study partners participated for personal benefit and altruism. They emphasized personal benefits more when their participants had a CDR > 0 than when they had a CDR = 0. This difference declined with participant age. The majority of study partners rated their ADRC participation as positive and meeting their goals. Although half reported at least one complaint, very few regretted participating. Those who reported that ADRC participation fulfilled their goals or had fewer complaints were more likely to have perfect attendance. Study partners requested more feedback about test results and better management of study visits. CONCLUSION: Study partners are motivated by both personal and altruistic goals. The salience of each goal depends on their trust in researchers and the participant's cognitive status and age. Retention may improve with perceived goal fulfillment and fewer complaints. Potential areas for improving retention are providing more information about the participant's test results and better management of study visits.

Longitudinal clinical, cognitive and biomarker profiles in dominantly inherited versus sporadic early-onset Alzheimer's disease.

Approximately 5% of Alzheimer's disease cases have an early age at onset (<65 years), with 5-10% of these cases attributed to dominantly inherited mutations and the remainder considered as sporadic. The extent to which dominantly inherited and sporadic early-onset Alzheimer's disease overlap is unknown. In this study, we explored the clinical, cognitive and biomarker profiles of early-onset Alzheimer's disease, focusing on commonalities and distinctions between dominantly inherited and sporadic cases. Our analysis included 117 participants with dominantly inherited Alzheimer's disease enrolled in the Dominantly Inherited Alzheimer Network and 118 individuals with sporadic early-onset Alzheimer's disease enrolled at the University of California San Francisco Alzheimer's Disease Research Center. Baseline differences in clinical and biomarker profiles between both groups were compared using t-tests. Differences in the rates of decline were compared using linear mixed-effects models. Individuals with dominantly inherited Alzheimer's disease exhibited an earlier age-at-symptom onset compared with the sporadic group [43.4 (SD ± 8.5) years versus 54.8 (SD ± 5.0) years, respectively, P < 0.001]. Sporadic cases showed a higher frequency of atypical clinical presentations relative to dominantly inherited (56.8% versus 8.5%, respectively) and a higher frequency of APOE-ε4 (50.0% versus 28.2%, P = 0.001). Compared with sporadic early onset, motor manifestations were higher in the dominantly inherited cohort [32.5% versus 16.9% at baseline (P = 0.006) and 46.1% versus 25.4% at last visit (P = 0.001)]. At baseline, the sporadic early-onset group performed worse on category fluency (P < 0.001), Trail Making Test Part B (P < 0.001) and digit span (P < 0.001). Longitudinally, both groups demonstrated similar rates of cognitive and functional decline in the early stages. After 10 years from symptom onset, dominantly inherited participants experienced a greater decline as measured by Clinical Dementia Rating Sum of Boxes [3.63 versus 1.82 points (P = 0.035)]. CSF amyloid beta-42 levels were comparable [244 (SD ± 39.3) pg/ml dominantly inherited versus 296 (SD ± 24.8) pg/ml sporadic early onset, P = 0.06]. CSF phosphorylated tau at threonine 181 levels were higher in the dominantly inherited Alzheimer's disease cohort (87.3 versus 59.7 pg/ml, P = 0.005), but no significant differences were found for t-tau levels (P = 0.35). In summary, sporadic and inherited Alzheimer's disease differed in baseline profiles; sporadic early onset is best distinguished from dominantly inherited by later age at onset, high frequency of atypical clinical presentations and worse executive performance at baseline. Despite these differences, shared pathways in longitudinal clinical decline and CSF biomarkers suggest potential common therapeutic targets for both populations, offering valuable insights for future research and clinical trial design.

Retaining Participants in Longitudinal Studies of Alzheimer's Disease.

BACKGROUND: Retention of study participants is essential to advancing Alzheimer's disease (AD) research and developing therapeutic interventions. However, recent multi-year AD studies have lost 10% to 54% of participants. OBJECTIVE: We surveyed a random sample of 443 participants (Clinical Dementia Rating [CDR]≤1) at four Alzheimer Disease Research Centers to elucidate perceived facilitators and barriers to continued participation in longitudinal AD research. METHODS: Reasons for participation were characterized with factor analysis. Effects of perceived fulfillment of one's own goals and complaints on attendance and likelihood of dropout were estimated with logistic regression models. Open-ended responses suggesting study improvements were analyzed with a Latent Dirichlet Allocation topic model. RESULTS: Factor analyses revealed two categories, personal benefit and altruism, as drivers of continued participation. Participants with cognitive impairment (CDR > 0) emphasized personal benefits more than societal benefits. Participants with higher trust in medical researchers were more likely to emphasize broader social benefits. A minority endorsed any complaints. Higher perceived fulfillment of one's own goals and fewer complaints were related to higher attendance and lower likelihood of dropout. Facilitators included access to medical center support and/or future treatment, learning about AD and memory concerns, and enjoying time with staff. Participants' suggestions emphasized more feedback about individual test results and AD research. CONCLUSION: The results confirmed previously identified facilitators and barriers. Two new areas, improved communication about individual test results and greater feedback about AD research, emerged as the primary factors to improve participation.

Predicting Symptom Onset in Sporadic Alzheimer Disease With Amyloid PET.

BACKGROUND AND OBJECTIVES: To predict when cognitively normal individuals with brain amyloidosis will develop symptoms of Alzheimer disease (AD). METHODS: Brain amyloid burden was measured by amyloid PET with Pittsburgh compound B. The mean cortical standardized uptake value ratio (SUVR) was transformed into a timescale with the use of longitudinal data. RESULTS: Amyloid accumulation was evaluated in 236 individuals who underwent >1 amyloid PET scan. The average age was 66.5 ± 9.2 years, and 12 individuals (5%) had cognitive impairment at their baseline amyloid PET scan. A tipping point in amyloid accumulation was identified at a low level of amyloid burden (SUVR 1.2), after which nearly all individuals accumulated amyloid at a relatively consistent rate until reaching a high level of amyloid burden (SUVR 3.0). The average time between levels of amyloid burden was used to estimate the age at which an individual reached SUVR 1.2. Longitudinal clinical diagnoses for 180 individuals were aligned by the estimated age at SUVR 1.2. In the 22 individuals who progressed from cognitively normal to a typical AD dementia syndrome, the estimated age at which an individual reached SUVR 1.2 predicted the age at symptom onset (R 2 = 0.54, p < 0.0001, root mean square error [RMSE] 4.5 years); the model was more accurate after exclusion of 3 likely misdiagnoses (R 2 = 0.84, p < 0.0001, RMSE 2.8 years). CONCLUSION: The age at symptom onset in sporadic AD is strongly correlated with the age at which an individual reaches a tipping point in amyloid accumulation.

Ante- and postmortem tau in autosomal dominant and late-onset Alzheimer's disease.

Antemortem tau positron emission tomography imaging suggests elevated tau pathology in autosomal dominant versus late-onset Alzheimer's disease at equivalent clinical stages, but does not implicate the specific tau pathologies responsible. Here we made stereological measurements of tau neurofibrillary tangles, neuritic plaques, and neuropil threads and found compared to late-onset Alzheimer's disease, autosomal dominant Alzheimer's disease showed even greater tangle and thread burdens. Regional tau burden resembled that observed in tau imaging of a separate cohort at earlier clinical stages. Finally, our results suggest tau imaging measures total tau burden in Alzheimer's disease, composed predominantly of tangle and thread pathology.

Association of Acquired and Heritable Factors With Intergenerational Differences in Age at Symptomatic Onset of Alzheimer Disease Between Offspring and Parents With Dementia.

Importance: Acquired and heritable traits are associated with dementia risk; however, how these traits are associated with age at symptomatic onset (AAO) of Alzheimer disease (AD) is unknown. Identifying the associations of acquired and heritable factors with variability in intergenerational AAO of AD could facilitate diagnosis, assessment, and counseling of the offspring of parents with AD. Objective: To quantify the associations of acquired and heritable factors with intergenerational differences in AAO of AD. Design, Setting, and Participants: This nested cohort study used data from the Knight Alzheimer Disease Research Center that included community-dwelling participants with symptomatic AD, parental history of dementia, and available DNA data who were enrolled in prospective studies of memory and aging from September 1, 2005, to August 31, 2016. Clinical, biomarker, and genetic data were extracted on January 17, 2017, and data analyses were conducted from July 1, 2017, to August 20, 2019. Main Outcomes and Measures: The associations of acquired (ie, years of education; body mass index; history of cardiovascular disease, hypertension, hypercholesterolemia, diabetes, active depression within 2 years, traumatic brain injury, tobacco use, and unhealthy alcohol use; and retrospective determination of AAO) and heritable factors (ie, ethnicity/race, paternal or maternal inheritance, parental history of early-onset dementia, APOE ε4 allele status, and AD polygenic risk scores) to intergenerational difference in AAO of AD were quantified using stepwise forward multivariable regression. Missense or frameshift variants within genes associated with AD pathogenesis were screened using whole-exome sequencing. Results: There were 164 participants with symptomatic AD, known parental history of dementia, and available DNA data (mean [SD] age, 70.9 [8.3] years; 90 [54.9%] women) included in this study. Offspring were diagnosed with symptomatic AD a mean (SD) 6.1 (10.7) years earlier than their parents (P < .001). The adjusted R2 for measured acquired and heritable factors for intergenerational difference in AAO of AD was 0.29 (F8,155 = 9.13; P < .001). Paternal (ß = -9.52 [95% CI, -13.79 to -5.25]) and maternal (ß = -6.68 [95% CI, -11.61 to -1.75]) history of dementia, more years of education (ß = -0.58 [95% CI -1.08 to -0.09]), and retrospective determination of AAO (ß = -3.46 [95% CI, -6.40 to -0.52]) were associated with earlier-than-expected intergenerational difference in AAO of AD. Parental history of early-onset dementia (ß = 21.30 [95% CI, 15.01 to 27.59]), presence of 1 APOE ε4 allele (ß = 5.00 [95% CI, 2.11 to 7.88]), and history of hypertension (ß = 3.81 [95% CI, 0.88 to 6.74]) were associated with later-than-expected intergenerational difference in AAO of AD. Missense or frameshift variants within genes associated with AD pathogenesis were more common in participants with the greatest unexplained variability in intergenerational AAO of AD (19 of 48 participants [39.6%] vs 26 of 116 participants [22.4%]; P = .03). Conclusions and Relevance: Acquired and heritable factors were associated with a substantial proportion of variability in intergenerational AAO of AD. Variants in genes associated with AD pathogenesis may contribute to unexplained variability, justifying further study.

Dural lymphatics regulate clearance of extracellular tau from the CNS.

BACKGROUND: Alzheimer's disease is characterized by two main neuropathological hallmarks: extracellular plaques of amyloid-ß (Aß) protein and intracellular aggregates of tau protein. Although tau is normally a soluble monomer that bind microtubules, in disease it forms insoluble, hyperphosphorylated aggregates in the cell body. Aside from its role in AD, tau is also involved in several other neurodegenerative disorders collectively called tauopathies, such as progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), some forms of frontotemporal dementia, and argyrophilic grain disease (AGD). The prion hypothesis suggests that after an initial trigger event, misfolded forms of tau are released into the extracellular space, where they spread through different brain regions, enter cells, and seeding previously normal forms. Thus understanding mechanisms regulating the clearance of extracellular tau from the CNS is important. The discovery of a true lymphatic system in the dura and its potential role in mediating Aß pathology prompted us to investigate its role in regulating extracellular tau clearance. METHODS: To study clearance of extracellular tau from the brain, we conjugated monomeric human tau with a near-infrared dye cypate, and injected this labeled tau in the parenchyma of both wild-type and K14-VEGFR3-Ig transgenic mice, which lack a functional CNS lymphatic system. Following injection we performed longitudinal imaging using fluorescence molecular tomography (FMT) and quantified fluorescence to calculate clearance of tau from the brain. To complement this, we also measured tau clearance to the periphery by measuring plasma tau in both groups of mice. RESULTS: Our results show that a significantly higher amount of tau is retained in the brains of K14-VEGFR3-Ig vs. wild type mice at 48 and 72 h post-injection and its subsequent clearance to the periphery is delayed. We found that clearance of reference tracer human serum albumin (HSA) was also significantly delayed in the K14-VEGFR3-Ig mice. CONCLUSIONS: The dural lymphatic system appears to play an important role in clearance of extracellular tau, since tau clearance is impaired in the absence of functional lymphatics. Based on our baseline characterization of extracellular tau clearance, future studies are warranted to look at the interaction between tau pathology and efficiency of lymphatic function.