Characterization of cerebellar amyloid-β deposits in Alzheimer disease

Cerebellar amyloid-β (Aβ) plaques are a component of the diagnostic criteria used in Thal staging and ABC scoring for Alzheimer disease (AD) neuropathologic change. However, Aβ deposits in this anatomic compartment are unique and under-characterized; and their relationship with other pathological findings are largely undefined. In 73 cases of pure or mixed AD with an A3 score in the ABC criteria, parenchymal (plaques) and vascular (cerebral amyloid angiopathy [CAA]) cerebellar Aβ-42 deposits were characterized with respect to localization, morphology, density, and intensity. Over 85% of cases demonstrated cerebellar Aβ-42 parenchymal staining that correlated with a Braak stage V-VI/B3 score (p < 0.01). Among the 63 with cerebellar Aβ-42 deposits, a diffuse morphology was observed in 75% of cases, compact without a central dense core in 32%, and compact with a central dense core in 16% (all corresponding to plaques evident on hematoxylin and eosin staining). Cases with Purkinje cell (PC) loss showed higher proportions of PC layer Aβ-42 staining than cases without PC loss (88% vs 44%, p = 0.02), suggesting a link between Aβ-42 deposition and PC damage. Among all 73 cases, CAA was observed in the parenchymal vessels of 19% of cases and in leptomeningeal vessels in 44% of cases.

Study of neuropathological changes and dementia in 100 centenarians in The 90+ Study

INTRODUCTION

The association between neuropathological changes and dementia among centenarians and nonagenarians remains unclear.

METHODS

We examined brain tissue from 100 centenarians and 297 nonagenarians from The 90+ Study, a community-based longitudinal study of aging. We determined the prevalence of 10 neuropathological changes and compared their associations with dementia and cognitive performance between centenarians and nonagenarians.

RESULTS

A total of 59% of centenarians and 47% of nonagenarians had at least four neuropathological changes. In centenarians, neuropathological changes were associated with higher odds of dementia and, compared to nonagenarians, the odds were not attenuated. For each additional neuropathological change, the Mini-Mental State Examination score was lower by 2 points for both groups.

DISCUSSION

Neuropathological changes continue to be strongly related to dementia in centenarians, highlighting the importance of slowing or preventing the development of multiple neuropathological changes in the aging brain to maintain cognitive health.

HIGHLIGHTS

Individual and multiple neuropathological changes are frequent in centenarians. These neuropathological changes are strongly associated with dementia. There is no attenuation of this association with age.

Neuropathology of microbleeds in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

Cerebral microbleeds (CMBs) detected on magnetic resonance imaging are common in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The neuropathologic correlates of CMBs are unclear. In this study, we characterized findings relevant to CMBs in autopsy brain tissue of 8 patients with genetically confirmed CADASIL and 10 controls within the age range of the CADASIL patients by assessing the distribution and extent of hemosiderin/iron deposits including perivascular hemosiderin leakage (PVH), capillary hemosiderin deposits, and parenchymal iron deposits (PID) in the frontal cortex and white matter, basal ganglia and cerebellum. We also characterized infarcts, vessel wall thickening, and severity of vascular smooth muscle cell degeneration. CADASIL subjects had a significant increase in hemosiderin/iron deposits compared with controls. This increase was principally seen with PID. Hemosiderin/iron deposits were seen in the majority of CADASIL subjects in all brain areas. PVH was most pronounced in the frontal white matter and basal ganglia around small to medium sized arterioles, with no predilection for the vicinity of vessels with severe vascular changes or infarcts. CADASIL subjects have increased brain hemosiderin/iron deposits but these do not occur in a periarteriolar distribution. Pathogenesis of these lesions remains uncertain.

Chronic kidney disease promotes cerebral microhemorrhage formation

BACKGROUND

Chronic kidney disease (CKD) is increasingly recognized as a stroke risk factor, but its exact relationship with cerebrovascular disease is not well-understood. We investigated the development of cerebral small vessel disease using in vivo and in vitro models of CKD.

METHODS

CKD was produced in aged C57BL/6J mice using an adenine-induced tubulointerstitial nephritis model. We analyzed brain histology using Prussian blue staining to examine formation of cerebral microhemorrhage (CMH), the hemorrhagic component of small vessel disease and the neuropathological substrate of MRI-demonstrable cerebral microbleeds. In cell culture studies, we examined effects of serum from healthy or CKD patients and gut-derived uremic toxins on brain microvascular endothelial barrier.

RESULTS

CKD was induced in aged C57BL/6J mice with significant increases in both serum creatinine and cystatin C levels (p < 0.0001) without elevation of systolic or diastolic blood pressure. CMH was significantly increased and positively correlated with serum creatinine level (Spearman r = 0.37, p < 0.01). Moreover, CKD significantly increased Iba-1-positive immunoreactivity by 51% (p < 0.001), induced a phenotypic switch from resting to activated microglia, and enhanced fibrinogen extravasation across the blood-brain barrier (BBB) by 34% (p < 0.05). On analysis stratified by sex, the increase in CMH number was more pronounced in male mice and this correlated with greater creatinine elevation in male compared with female mice. Microglial depletion with PLX3397 diet significantly decreased CMH formation in CKD mice without affecting serum creatinine levels. Incubation of CKD serum significantly reduced transendothelial electrical resistance (TEER) (p < 0.01) and increased sodium fluorescein permeability (p < 0.05) across the endothelial monolayer. Uremic toxins (i.e., indoxyl sulfate, p-cresyl sulfate, and trimethylamine-N-oxide) in combination with urea and lipopolysaccharide induced a marked drop in TEER compared with the control group (p < 0.0001).

CONCLUSIONS

CKD promotes the development of CMH in aged mice independent of blood pressure but directly proportional to the degree of renal impairment. These effects of CKD are likely mediated in part by microglia and are associated with BBB impairment. The latter is likely related to gut-derived bacteria-dependent toxins classically associated with CKD. Overall, these findings demonstrate an important role of CKD in the development of cerebral small vessel disease.

Abstract TP223: Cerebral Microbleeds In Sickle Cell Disease

Introduction: Stroke due to sickle cell disease is often attributed to large vessel involvement in the disorder. The role of cerebral microvascular disease in sickle cell disease has received little attention. In this study, we examined development of cerebral microvascular lesions in a mouse model of sickle cell disease. We focused on cerebral microhemorrhages, the neuropathologic substrate of cerebral microbleeds.

Methods: We studied microvascular disease in a well-characterized mouse model of humanized transgenic sickle (HbSS-BERK) and control (HbAA-BERK) mice expressing >99% human sickle hemoglobin (Hb) and normal human HbA, respectively. HbSS-BERK express human α and βS globins on a mixed genetic background. HbAA-BERK mice express normal human α and βA globin thus producing only normal human hemoglobin A, on the same mixed genetic background as HbSS-BERK. Seven- to nine-month-old mice (N=18 HbSS, N=12 HbAA) were examined. We collected mouse brains and performed standard histology using Prussian blue staining to detect CMH formation at 20x magnification. The average number, total area, and size of Prussian blue-positive deposits were quantified. In separate studies, Toluidine Blue staining was used to identify mast cells.

Results: HbSS mice showed approximately 70% more cerebral microhemorrhages than controls (mean±SE of 1.17± 0.22 vs 0.69±0.13 number/cm 2, p=0.04). Lesion size did not differ between HbSS and control mice. Activated mast cells were identified in HbSS mouse brain but not in control mice.

Conclusions: In this mouse model of sickle cell disease, HbSS mice demonstrated significantly increased development of cerebral microhemorrhages. These findings emphasize the potential importance of cerebral microvascular disease in sickle cell disease. Cerebral mast cell activation in sickle cell disease may be a novel target for investigation.

LATE and potential estrogen-related risk factors collected 30 years earlier: The 90+ Study

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is a recently described neuropathological construct associated with dementia. This study aimed to investigate in an autopsy study, LATE-NC and its associations with potential estrogen-related risk factors collected about 30 years before death. Participants were part of The 90+ Study and had, as part of the Leisure World Cohort Study, provided information on menstrual and reproductive variables and details of use of estrogen replacement therapy (ERT). No menstrual and reproductive variable showed an association with LATE-NC. Use of ERT, especially long-term use (15+ years) and more recent use (within 1 year of completing the questionnaire), was associated with reduced risk. The odds were significantly lower for long-term (0.39, 95% confidence interval [CI]: 0.16-0.95) and recent use (0.39, 95% CI: 0.16-0.91) compared with no use. In conclusion, we found that women who reported long-term ERT in their 50s and 60s had a significantly reduced odds of harboring LATE-NC when they died in the 10th and 11th decades of their lives. Our study adds to the existing literature reporting seemingly protective effect of peri- and postmenopausal ERT against neurodegenerative dementia.

Alzheimer's Disease Neuropathologic Change and Vitamin Supplement Use Decades Earlier: The 90+ Study

BACKGROUND

Alzheimer's disease (AD) is the most common cause of dementia. AD neuropathologic change (ADNC) likely begins decades before clinical manifestations. One mechanism implicated in AD is oxidative stress. We explored the potential association of ADNC with antioxidant vitamin supplements taken about 30 years before death.

METHODS

The 264 brain-autopsied participants were part of The 90+ Study, a longitudinal study of aging among people aged 90+ years, and originally members of the Leisure World Cohort Study, a population-based health study established in the 1980s. Intake of supplemental vitamins A, C, and E was collected by the Leisure World Cohort Study about 30 years before ADNC assessment. Odds ratios of ADNC (intermediate/high vs. none/low) for vitamin intake were estimated using logistic regression.

RESULTS

The adjusted odds ratio (95% CI) of ADNC was 0.52 (0.29-0.92) for vitamin E supplements and 0.51 (0.27-0.93) for vitamin C supplements. Supplemental vitamin E intake was the first variable, after education, to enter the stepwise model. Intake of vitamin A or C did not improve the model fit.

CONCLUSIONS

The observed association of ADNC and supplemental vitamin E intake decades earlier suggests a beneficial effect and supports further investigation into a nutritional approach to preventing AD with vitamin supplementation.

Comparative studies between the murine immortalized brain endothelial cell line (bEnd.3) and induced pluripotent stem cell-derived human brain endothelial cells for paracellular transport

Brain microvascular endothelial cells, forming the anatomical site of the blood-brain barrier (BBB), are widely used as in vitro complements to in vivo BBB studies. Among the immortalized cells used as in vitro BBB models, the murine-derived bEnd.3 cells offer culturing consistency and low cost and are well characterized for functional and transport assays, but result in low transendothelial electrical resistance (TEER). Human-induced pluripotent stem cells differentiated into brain microvascular endothelial cells (ihBMECs) have superior barrier properties, but the process of differentiation is time-consuming and can result in mixed endothelial-epithelial gene expression. Here we performed a side-by-side comparison of the ihBMECs and bEnd.3 cells for key paracellular diffusional transport characteristics. The TEER across the ihBMECs was 45- to 68-fold higher than the bEnd.3 monolayer. The ihBMECs had significantly lower tracer permeability than the bEnd.3 cells. Both, however, could discriminate between the paracellular permeabilities of two tracers: sodium fluorescein (MW: 376 Da) and fluorescein isothiocyanate (FITC)-dextran (MW: 70 kDa). FITC-dextran permeability was a strong inverse-correlate of TEER in the bEnd.3 cells, whereas sodium fluorescein permeability was a strong inverse-correlate of TEER in the ihBMECs. Both bEnd.3 cells and ihBMECs showed the typical cobblestone morphology with robust uptake of acetylated LDL and strong immuno-positivity for vWF. Both models showed strong claudin-5 expression, albeit with differences in expression location. We further confirmed the vascular endothelial- (CD31 and tube-like formation) and erythrophagocytic-phenotypes and the response to inflammatory stimuli of ihBMECs. Overall, both bEnd.3 cells and ihBMECs express key brain endothelial phenotypic markers, and despite differential TEER measurements, these in vitro models can discriminate between the passage of different molecular weight tracers. Our results highlight the need to corroborate TEER measurements with different molecular weight tracers and that the bEnd.3 cells may be suitable for large molecule transport studies despite their low TEER.

Magnetic Resonance Imaging Findings in High School Football Players: Brain and Cervical Spine

Football exposes its players to traumatic brain, neck, and spinal injury. It is unknown whether the adolescent football player develops imaging abnormalities of the brain and spine that are detectable on magnetic resonance imaging (MRI). The objective of this observational study was to identify potential MRI signatures of early brain and cervical spine (c-spine) injury in high school football players. Eighteen football players (mean age, 17.0 ± 1.5 years; mean career length, 6.3 ± 4.0 years) had a baseline brain MRI, and 7 had a follow-up scan 9–42 months later. C-spine MRIs were performed on 11 of the 18 subjects, and 5 had a follow-up scan. C-spine MRIs from 12 age-matched hospital controls were also retrospectively retrieved. Brain MRIs were reviewed by a neuroradiologist, and no cerebral microbleeds were detected. Three readers (a neuroradiologist, a neurosurgeon, and an orthopedic spine surgeon) studied the cervical intervertebral discs at six different cervical levels and graded degeneration using an established five-grade scoring system. We observed no statistically significant difference in disc degeneration or any trend toward increased disc degeneration in the c-spine of football players as compared with age-matched controls. Further research is needed to validate our findings and better understand the true impact of contact sports on young athletes.

Abstract TP127: Hypertension Provokes Development Of Cerebral Microhemorrhages In A Mouse Model

Introduction: Cerebral microhemorrhages (CMH) are the pathological substrate for cerebral microbleeds, represent focal hemosiderin deposits on MRI, and are associated with increased risk of cognitive impairment and ischemic and hemorrhagic stroke. Aging and hypertension are the most common risk factors for cerebral microbleeds. In this study, we analyzed the effect of hypertension on the development of CMH in a mouse model of aging.

Methods: Hypertension was induced in aged (17 months old) female and male C57BL/6J mice, via infusion of angiotensin II (ATII) at 1000 ng/kg/min via Alzet pump over four weeks. We further examined underlying mechanism by inhibiting ATII type 1 receptor (AT1R) with telmisartan, via drinking water for 4 weeks. We collected mouse brains and performed standard histology using Prussian blue staining to detect CMH formation at 20x magnification. We also examined correlations between CMH burden and systolic (SBP) and diastolic (DPB) blood pressures.

Results: ATII infusion induced significant increases in SBP (121±4 mmHg to 159±6 mmHg; p<0.001) and DBP (94±4 mmHg to 129±7 mmHg; p<0.001). Telmisartan completely blocked ATII-induced blood pressure elevation. Hypertension increased the number of CMH (p=0.01) in male and female mice. In animals with ATII infusion, number of CMH were positively correlated with SBP (r=0.45, p=0.02) and DBP (r=0.47, p=0.01). Telmisartan reduced by 55% the number of ATII-induced CMH, but compared to controls, CMH number remained elevated (p=0.03) in telmisartan-treated animals.

Conclusions: ATII-induced hypertension promotes the development of CMH in aged mice in a manner that appears dependent on the extent of hypertension. However, in the presence of ATII with ATIR blockade, CMH develops even in the absence of hypertension. These findings emphasize the importance of presence and extent of hypertension in development of CMH in aging, as well as the significance of non-AT1R-mediated pathways independent of hypertension in ATII-induced CMH.

Abstract 87: Chronic Kidney Disease Induces Cerebral Microhemorrhages In Aged Mice

Introduction: Chronic kidney disease (CKD) is increasingly recognized as a risk factor of cerebral microvascular disease, but its association with common neuropathologic changes is not well understood. We investigated the relationship between CKD and development of cerebral microhemorrhages (CMH) in a mouse model of aging. We also examined the effect of CKD on endothelial cell function in an in vitro blood-brain barrier (BBB) model.

Methods: CKD was produced in aged C57BL/6J mice using an adenine-induced tubulointerstitial nephritis model. We performed standard histology using Prussian blue staining to examine CMH formation. Correlations between CMH burden and serum creatinine levels were assessed. In cell culture studies, human brain microvascular endothelial cells (ihBMECs) derived from induced pluripotent stem cell line IMR90-4 were treated with serum from healthy or CKD patient donors for up to 3 days. Transendothelial electrical resistance (TEER) and tracer (sodium fluorescein) permeability across the ihBMEC monolayer were measured to assess the integrity of the in vitro BBB.

Results: CKD induction in aged C57BL/6J mice caused a significant increase in both serum creatinine level (0.09±0.01 mg/dL to 0.43±0.03 mg/dL, p<0.001) and CMH number (p<0.05), without alteration of systolic or diastolic blood pressure. Number of CMH was positively correlated with serum creatinine level (r=0.41, p<0.001). Incubation of CKD serum with ihBMECs significantly reduced TEER by 26% (p<0.05) and increased sodium fluorescein permeability by 100% (p<0.01) across the ihBMEC monolayer.

Conclusions: Adenine-induced CKD promotes the development of CMH in aged C57BL/6J mice independent of blood pressure, and extent of CMH development is directly proportional to degree of renal insufficiency. Moreover, serum-derived factors in CKD disrupt BBB integrity in vitro. These findings suggest CKD provokes microvascular injury at the capillary level, leading to CMH formation in this model.

Prevalence of cerebral small vessel disease in a Fabry disease cohort

Objective

To characterize the prevalence of brain ischemia and cerebral small vessel disease in a cohort of patients with Fabry disease (FD) seen at an academic medical center.

Background

FD is an inherited X-linked lysosomal storage disorder with central nervous system involvement. Limited data are available in the literature on the cerebrovascular neuroimaging findings in FD, and the reported prevalence of stroke symptoms and cerebral small vessel disease has varied widely.

Design/methods

Brain MRI was performed in 21 patients with FD followed at University of California Irvine Medical Center. Stroke symptoms were assessed and quantification of cerebral microvascular disease was performed using small vessel disease (SVD) score. Lacunes and deep white matter hyperintensities were scored on a four-point scale of 0 (absent) and 1–3 to account for increasing severity; microbleeds were scored 0 (absent) or 1 (present). The total SVD score is the sum of the three components and ranges from 0 to 7.

Results

Nearly 43% (9/21) of our FD cohort (aged 32–81 years, mean = 50) had a SVD score of one or higher, all of whom were aged 50 or more years. The most common MRI-defined SVD was white matter hyperintensities (9/9, 100%), followed by microbleeds (6/9, 66%), and lacunes (3/9, 33%). The three patients with previous strokes had some of the highest SVD scores reported in the cohort (scores 3–5).

Conclusions

In this cohort, the prevalence of SVD (43%) was three times higher than prevalence of stroke symptoms. SVD score was highest in the those who had experienced a stroke. These findings emphasize the importance of routine MRI screening of patients with FD in order to identify and treat high risk patients.

Kidney Function Is Not Related to Brain Amyloid Burden on PET Imaging in The 90+ Study Cohort

Cognitive decline is common in chronic kidney disease (CKD). While the evidence of vascular cognitive impairment in this population is robust, the role of Alzheimer's pathology is unknown. We evaluated serum cystatin C-estimated glomerular filtration rate (eGFR), brain amyloid-β positron emission tomography (PET) imaging, and cognitive function in 166 participants from The 90+ Study. Mean age was 93 years (range 90-107) and 101 (61%) were women; 107 participants had normal cognitive status while 59 participants had cognitive impairment no dementia (CIND) or dementia. Mean ± standard deviation cystatin C was 1.59 ± 0.54 mg/L with eGFR 40.7 ± 18.7 ml/min/1.73m2. Higher amyloid-β burden was associated with dementia, but not with age, diabetes, hypertension, or cardiovascular disease. We found no association between brain amyloid-β burden and cystatin C eGFR. We previously reported that kidney function was associated with cognition and cerebral microbleeds in the same cohort of oldest-old adults (90+ years old). Collectively, these findings suggest that microvascular rather than Alzheimer's pathology drives CKD-associated cognitive dysfunction in this population.

Insights Into the Mechanisms of Brain Endothelial Erythrophagocytosis

The endothelial cells which form the inner cellular lining of the vasculature can act as non-professional phagocytes to ingest and remove emboli and aged/injured red blood cells (RBCs) from circulation. We previously demonstrated an erythrophagocytic phenotype of the brain endothelium for oxidatively stressed RBCs with subsequent migration of iron-rich RBCs and RBC degradation products across the brain endothelium in vivo and in vitro, in the absence of brain endothelium disruption. However, the mechanisms contributing to brain endothelial erythrophagocytosis are not well defined, and herein we elucidate the cellular mechanisms underlying brain endothelial erythrophagocytosis. Murine brain microvascular endothelial cells (bEnd.3 cells) were incubated with tert-butyl hydroperoxide (tBHP, oxidative stressor to induce RBC aging in vitro)- or PBS (control)-treated mouse RBCs. tBHP increased the reactive oxygen species (ROS) formation and phosphatidylserine exposure in RBCs, which were associated with robust brain endothelial erythrophagocytosis. TNFα treatment potentiated the brain endothelial erythrophagocytosis of tBHP-RBCs in vitro. Brain endothelial erythrophagocytosis was significantly reduced by RBC phosphatidylserine cloaking with annexin-V and with RBC-ROS and phosphatidylserine reduction with vitamin C. Brain endothelial erythrophagocytosis did not alter the bEnd.3 viability, and tBHP-RBCs were localized with early and late endosomes. Brain endothelial erythrophagocytosis increased the bEnd.3 total iron pool, abluminal iron levels without causing brain endothelial monolayer disruption, and ferroportin levels. In vivo, intravenous tBHP-RBC injection in aged (17–18 months old) male C57BL/6 mice significantly increased the Prussian blue-positive iron-rich lesion load compared with PBS-RBC-injected mice. In conclusion, RBC phosphatidylserine exposure and ROS are key mediators of brain endothelial erythrophagocytosis, a process which is associated with increased abluminal iron in vitro. tBHP-RBCs result in Prussian blue-positive iron-rich lesions in vivo. Brain endothelial erythrophagocytosis may provide a new route for RBC/RBC degradation product entry into the brain to produce iron-rich cerebral microhemorrhage-like lesions.

Stroke Preventability in Large Vessel Occlusion Treated With Mechanical Thrombectomy

Objective: The preventability of strokes treated by mechanical thrombectomy is unknown. The purpose of this study was to analyze stroke preventability for patients treated with mechanical thrombectomy for large vessel occlusion.

Methods: We conducted retrospective analyses of 300 patients (mean ± SE age 69 ± 0.9 years, range 18–97 years; 53% male) treated with mechanical thrombectomy for large vessel occlusion from January 2008 to March 2019. We collected data including demographics, NIH Stroke Scale (NIHSS) at onset, and (beginning in 2015) classified 90-day outcome by modified Rankin Scale (mRS). Patients were evaluated using a Stroke Preventability Score (SPS, 0 to 10 points) based on how well patients had been treated given their hypertension, hyperlipidemia, atrial fibrillation, and prior stroke history. We examined the relationship of SPS with NIHSS at stroke onset and with mRS outcome at 90 days.

Results: SPS was calculated for 272 of the 300 patients, with mean ± SE of 2.1 ± 0.1 (range 0–8); 89 (33%) had no preventability (score 0), 120 (44%) had low preventability (score 1–3), and 63 (23%) had high preventability (score 4 or higher). SPS was significantly correlated with age (r = 0.32, p < 0.0001), while NIHSS (n = 267) was significantly higher (p = 0.03) for patients with high stroke preventability vs. low/no preventability [18.8 ± 0.92 (n = 62) vs. 16.5 ± 0.51 (n = 205)]. Among 118 patients with mRS, outcome was significantly worse (p = 0.04) in patients with high stroke preventability vs. low/no preventability [4.7 ± 0.29 (n = 28) vs. 3.8 ± 0.21 (n = 90)]. The vast majority of patients with high stroke preventability had inadequately treated atrial fibrillation (85%, 53/62).

Conclusions: Nearly one quarter of stroke patients undergoing mechanical thrombectomy had highly preventable strokes. While stroke preventability showed some relationship to stroke severity at onset and outcome after treatment, preventability had the strongest association with age. These findings emphasize the need for improved stroke prevention in the elderly.

Cognition and Political Ideology in Aging

OBJECTIVE

The impact of cognitive function and decline on political ideology is unknown. We studied the relationship between cognition and both political orientation and political policy choices in a population of older persons.

DESIGN

Longitudinal investigation.

SETTING

A retirement community and its surroundings in Southern California.

PARTICIPANTS

151 members of a longitudinal investigation of aging and dementia in the oldest-old (the 90+ Study), mean age 95 years.

MEASUREMENTS

Participants self-reported their political ideology (7-point scale from extremely liberal to extremely conservative) and policy preferences for federal spending on public schooling, aid to the poor, and protecting the environment, as well as on preferences on immigration rates, death penalty, and university admission. The same political survey was mailed to participants twice: at time one and 6-months later. Cognitive function based on neurological examination and cognitive testing was classified as normal (55%), cognitive impairment/not dementia (CIND) (33%), or dementia (12%). We calculated rank correlations between ideology and policy choices, stratified by cognitive status, and agreement between Surveys 1 and 2.

RESULTS

Political ideology/orientation was highly consistent over a six-month period (84% agreement) among the 122 who returned the second survey, with no significant relationship to cognitive status. Among cognitively impaired (CIND and dementia), however, there was significant loss of consistency between an individual's political orientation and their policy choices. Level of political engagement was high for participants, with more than 90% voting in the 2016 presidential election.

CONCLUSION

In this population of older persons, political identification on the liberal-conservative spectrum was resilient despite cognitive decline, but its meaning and function were changed. For the cognitively impaired it remained a self-defining label, but no longer operated as a higher order framework for orienting specific policy preferences. There appeared to be loss of coherence between the political orientation and political policy choices of cognitively impaired individuals. Given the high level of political engagement of these individuals, these results have substantial public policy implications.

Mechanisms of Cerebral Microbleeds

Cerebral microbleeds (CMB) are a common MRI finding, representing underlying cerebral microhemorrhages (CMH). The etiology of CMB and microhemorrhages is obscure. We conducted a pathological investigation of CMH, combining standard and immunohistological analyses of postmortem human brains. We analyzed 5 brain regions (middle frontal gyrus, occipital pole, rostral cingulate cortex, caudal cingulate cortex, and basal ganglia) of 76 brain bank subjects (mean age ± SE 90 ± 1.4 years). Prussian blue positivity, used as an index of CMH, was subjected to quantitative analysis for all 5 brain regions. Brains from the top and bottom quartiles (n = 19 each) were compared for quantitative immunohistological findings of smooth muscle actin, claudin-5, and fibrinogen, and for Sclerosis Index (SI) (a measure of arteriolar remodeling). Brains in the top quartile (i.e. with most extensive CMH) had significantly higher SI in the 5 brain regions combined (0.379 ± 0.007 vs 0.355 ± 0.008; p < 0.05). These findings indicate significant coexistence of arteriolar remodeling with CMH. While these findings provide clues to mechanisms of microhemorrhage development, further studies of experimental neuropathology are needed to determine causal relationships.

Cystatin C, cognition, and brain MRI findings in 90+-year-olds

Chronic kidney disease is emerging as a novel risk factor for cerebrovascular disease, but this association remains largely unexplored in older adults. Cystatin C is a more accurate measure than creatinine of kidney function in the elderly. We evaluated cystatin C, cognitive function, and brain imaging in 193 participants from The 90+ Study neuroimaging component. The mean age was 93.9 years; 61% were women. Mean cystatin C was 1.62 mg/L with estimated glomerular filtration rate 39.2 mL/min/1.73 m². Performance on measures of global cognition, executive function, and visual-spatial ability declined at higher tertiles of cystatin C (lower kidney function). Higher cystatin C was significantly associated with infratentorial microbleeds and lower gray matter volume. Adjusted risk of incident dementia was increased in the middle and high cystatin C tertile groups compared with the low group (hazard ratio in highest tertile 3.81 [95% confidence interval 1.14-12.7]), which appeared to be explained in part by the presence of cerebral microbleeds. Overall, cystatin C was associated with cognitive performance, brain imaging pathology, and decline to dementia in this oldest-old cohort.

Prior endogenous and exogenous estrogen and incident dementia in the 10th decade of life: The 90+ Study

Objective: This study aimed to investigate the association of endogenous and exogenous estrogen exposure with risk of incident dementia in the oldest-old (age 90+ years).Methods: Participants were part of The 90+ Study, a longitudinal study begun in 2003 of aging and dementia among people aged 90+ years. Menstrual, reproductive, and menopausal data were collected in the 1980s as part of the population-based Leisure World Cohort Study. Cognitive status at baseline was determined from an in-person neurological evaluation with biannual follow-up through June 2019. Hazard ratios (HRs) of dementia associated with estrogen-related variables were estimated using Cox regression analysis. No adjustment was made for multiple comparisons.Results: A total of 424 women without dementia at baseline had at least one follow-up evaluation. The mean age was 68.5 years at enrollment in the Leisure World Cohort Study, 93.2 years at enrollment in The 90+ Study, and 96.5 years at last follow-up. During follow-up (mean 3.4 years) dementia was diagnosed in 209 (49%) participants. No individual menstrual, reproductive, menopausal, or estrogen replacement variable was associated with risk of incident dementia after age 90 years. However, women with a high endogenous estrogen exposure index (summarizing exposure from menarche to menopause) had a non-significant 25% lower risk (HR = 0.75, 95% confidence interval 0.53-1.06).Conclusions: Prior exposure to estrogen, endogenous or exogenous, had little effect on risk of dementia in the 10th decade of life.

Abstract WP261: The Left Atrial Septal Pouch: A New Stroke Risk Factor?

Background: The left atrial septal pouch (LASP) is a common anatomic variant produced by the incomplete fusion of septa primum and secondum at the inter-atrial septum, thus creating a potential embolic source from an open flap or blind pouch in the left atrium. Our prior work demonstrated increased prevalence of LASP in cryptogenic strokes (Frontiers Neurology 3-24-15). The aim of the current study was to examine the prevalence of LASP in a separate, more recent group of stroke patients and control subjects who underwent transesophageal echocardiography (TEE).

Methods: We examined consecutive TEE studies performed between July, 2011 and December, 2018 at UC Irvine Medical Center. Prevalence of LASP was determined in TEE studies referred for ischemic stroke or TIA (“stroke subjects”), and compared to LASP prevalence in patients undergoing TEE for other reasons (“control subjects”). Stroke subtyping was performed using TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria.

Results: TEE studies were performed on 221 cerebrovascular cases and 164 control subjects. Age and sex were 57±1 years (mean±SE) and 53% male for stroke subjects, and 56±1 years and 62% male for control subjects. Prevalence of LASP was 24% (40/164) in control subjects, 17% (24/138) in non-cryptogenic stroke subjects, and 36% (30/83) in cryptogenic stroke subjects. LASP prevalence was significantly higher for cryptogenics compared to the other groups (p=0.007). There was no significant difference between LASP prevalence in controls vs non-cryptogenic stroke. Elimination from analysis of subjects with other inter-atrial septal abnormalities (ie, patent foramen ovale or atrial septal defect) did not significantly change results.

Conclusions: These findings demonstrate an increased prevalence of LASP in cryptogenic stroke, confirming our prior published findings. Given the plausibility of LASP acting as a thromboembolic nidus, additional studies are needed to determine the generalizability of these findings and their therapeutic implications.

Cerebral Microbleeds in a Stroke Prevention Clinic

The objective of this study was to assess the effectiveness of a stroke clinic in stroke prevention and progression of cerebral microbleeds (CMB). We conducted a retrospective observational study of patients who visited a stroke clinic between January 2011 and March 2017. Susceptibility-weighted imaging (SWI) MRI studies were obtained at baseline and follow-up visits to identify new infarctions and CMB progression. Patients with CMB who also underwent brain computed tomography (CT) imaging were identified and their cerebral arterial calcification was quantified to evaluate the relationship between the extent of intracranial calcification and CMB burden. A total of 64 stroke patients (mean age 73.1 ± 11.0, 47% males) had CMB on baseline and follow-up MRI studies. During a mean follow-up period of 22.6 months, four strokes occurred (4/64, 6%; 3 ischemic, 1 hemorrhagic), producing mild neurological deficit. Progression of CMB was observed in 54% of patients with two MRIs and was significantly associated with length of follow-up. Subjects with intracranial calcification score > 300 cm³ had higher CMB count than those with scores <300 cm³ at both baseline (12.6 ± 11.7 vs. 4.9 ± 2.2, p = 0.02) and follow-up (14.1 ± 11.8 vs. 5.6 ± 2.4, p = 0.03) MRI evaluations. Patients with CMB had a relatively benign overall clinical course. The association between CMB burden and intracranial calcification warrants further study.

Effects of Dabigatran in Mouse Models of Aging and Cerebral Amyloid Angiopathy

Oral anticoagulants are a critical component of stroke prevention, but carry a risk of brain hemorrhage. These hemorrhagic complications tend to occur in elderly individuals, especially those with predisposing conditions such as cerebral amyloid angiopathy (CAA). Clinical evidence suggests that non-vitamin K antagonist oral anticoagulants are safer than traditional oral anticoagulants. We analyzed whether the anticoagulant dabigatran produces cerebral microhemorrhage (the pathological substrate of MRI-demonstrable cerebral microbleeds) or intracerebral hemorrhage in aged mice with and without hemorrhage-predisposing angiopathy. We studied aged (22 months old) Tg2576 (a model of CAA) and wild-type (WT) littermate mice. Mice received either dabigatran etexilate (DE) (Tg N = 7; WT N = 10) or vehicle (Tg N = 9; WT N = 7) by gavage for 4 weeks. Anticoagulation effects of DE were confirmed using thrombin time assay. No mice experienced intracerebral hemorrhage. Cerebral microhemorrhage analysis, performed using Prussian-blue and H&E staining, showed no significant change in either number or size of cerebral microhemorrhage in DE-treated animals. Analysis of biochemical parameters for endothelial activation (ICAM-1), blood-brain barrier disruption (IgG, claudin-5, fibrinogen), microglial activation (Iba-1), or astrocyte activation (GFAP) showed neither exacerbation nor protective effects of DE in either Tg2576 or WT mice. Our study provides histological and biochemical evidence that aged mice, with or without predisposing factors for brain hemorrhage, tolerate anticoagulation with dabigatran. The absence of dabigatran-induced intracerebral hemorrhage or increased frequency of acute microhemorrhage may provide some reassurance for its use in high-risk patient populations.

Blood Pressure Circadian Variation, Cognition and Brain Imaging in 90+ Year-Olds

Purpose: To analyze the relationship between blood pressure (BP) variables, including circadian pattern, and cognition in 90+ year-olds.

Methods: Twenty-four hour ambulatory BP monitoring was completed on 121 participants drawn from a longitudinal study of aging and dementia in the oldest-old. Various measures of BP and its variability, including nocturnal dipping, were calculated. Each person was given both a neuropsychological test battery covering different cognitive domains and a neurological examination to determine cognitive status. Seventy-one participants had a brain magnetic resonance imaging (MRI) scan.

Results: Participants ranged in age from 90 to 102 years (mean = 93), about two-thirds were female, and nearly 80% had at least some college education. Mean nocturnal dips differed significantly between cognitively normal (n = 97) and impaired individuals (n = 24), with cognitively normal participants having on average greater nocturnal dips [6.6% vs. 1.3%, p = 0.006 for systolic BP (SBP); 11% vs. 4.4%, p = 0.002 for diastolic BP (DBP)]. Nocturnal dips were also related to performance on select cognitive test scores (especially those related to language, recent memory and visual-spatial ability), with individuals who performed below previously established median norms having significantly smaller nocturnal dips (both SBP and DBP) than those above the median. DBP reverse dippers had larger mean white matter hyperintensities (WMH as percent of total brain volume; 1.7% vs. 1.2%, 1.1% and 1.0% in extreme dippers, dippers, non-dippers) and a greater proportion had lobar cerebral microbleeds (CMBs; 44% vs. 0%, 7%, 16%, p < 0.05). Impaired participants had higher mean WMH than those with normal cognition (1.6% vs. 1.0% p = 0.03) and more tended to have CMB (31% vs. 20%, p = n.s.).

Conclusion: These findings suggest that cognitive dysfunction is associated with dysregulation in the normal circadian BP pattern. Further study is warranted of the potential role of WHM and CMB as mediators of this association.

Abstract TP422: Mechanisms of Cerebral Microbleeds

Cerebral microbleeds are a common MRI finding in the aging population, and reflect an underlying microscopic pathology of cerebral microhemorrhage. Pathogenesis of cerebral microbleeds remains obscure. We conducted a mechanistic investigation of the neuropathology of cerebral microhemorrhage, combining standard and immunohistochemistry analyses, and focusing on microvascular changes concurrent with microhemorrhage. We conducted a postmortem study of participants from the UCI Alzheimer’s Disease Research Center and The 90+ Study. We analyzed five brain regions (middle frontal gyrus, occipital pole, rostral cingulate cortex, caudal cingulate cortex, and basal ganglia) of 77 brain bank subjects (aged 90±10.8 years, mean±SEM ). Prussian blue-positivity, used as an index of cerebral microhemorrhage, was subjected to quantitative analysis for all five brain regions and compared with quantitative immunohistological findings of smooth muscle actin, claudin-5, fibrinogen, and platelet-derived growth factor receptor-beta (PDGFRβ), along with the sclerosis index, a measure of arteriolar injury. The top and bottom quartiles (n=19 each) for Prussian blue-positivity were compared for immunohistological findings and for sclerosis index. Subjects from the top quartile (ie, with most extensive cerebral microhemorrhage) had significantly higher sclerosis index in all five brain regions collectively (0.355±0.008 vs 0.379±0.007; p<0.05). In addition, PDGFRβ, an index of pericyte presence, was significantly lower in the top versus bottom quartiles in caudal cingulate cortex (82±7 vs 136±15 um 2 , p<0.01). The top and bottom quartiles did not differ significantly for smooth muscle actin, fibrinogen, or claudin-5 immunoreactivity. These findings indicate significant coexistence of arteriolar injury and cerebral microhemorrhage, as well as suggesting pericyte loss concurrent with cerebral microhemorrhage. Further studies are needed to determine the presence of causal roles for arteriolar injury and pericyte loss in the pathogenesis of cerebral microbleeds.

Abstract TP443: Effects of Dabigatran in Mouse Models of Aging and Cerebral Amyloid Angiopathy

Background: Oral anticoagulants are a critical component of stroke prevention, but carry a risk of brain hemorrhage. These hemorrhagic complications tend to occur in elderly individuals, especially those with predisposing conditions such as cerebral amyloid angiopathy. Clinical evidence suggests that newer oral anticoagulants (NOACs) are safer than traditional oral anticoagulants.

Objectives: We analyzed whether the NOAC dabigatran produces cerebral microhemorrhage (the pathological substrate of MRI-demonstrable cerebral microbleeds) or intracerebral hemorrhage in aged mice with and without hemorrhage-predisposing angiopathy.

Methods: We studied aged (22 months old) Tg2576 (a model of cerebral amyloid angiopathy) and wild-type (WT) littermate mice. Mice received either dabigatran etexilate (DE) (Tg N=7; WT N=10) or vehicle (Tg N=9; WT N=7) by gavage for four weeks. Anticoagulation effects of dabigatran were confirmed using diluted thrombin time assay.

Results: No mice experienced intracerebral hemorrhage. Cerebral microhemorrhage analysis, performed using Prussian-blue and H&E staining, showed no significant change in either number or size of cerebral microhemorrhage in DE-treated animals. Analysis of biochemical parameters for endothelial activation (ICAM-1), blood-brain barrier disruption (IgG, claudin-5, fibrinogen), microglial activation (Iba-1) or astrocyte activation (GFAP) showed neither exacerbation nor protective effects of DE in either Tg2576 or WT mice.

Conclusion: Our study provides histological and biochemical evidence that aged mice, with or without predisposing factors for brain hemorrhage, tolerate anticoagulation with dabigatran. Dabigatran did not induce intracerebral hemorrhage, and neither induced nor enlarged spontaneous cerebral microhemorrhage. These findings may provide some reassurance for the use of dabigatran in high-risk patient populations.

Aging exacerbates development of cerebral microbleeds in a mouse model

Background

Cerebral microhemorrhages (CMH) are commonly found in the aging brain. CMH are also the neuropathological substrate of cerebral microbleeds (CMB), demonstrated on brain MRI. Recent studies demonstrate the importance of systemic inflammation in CMH development, but the relationships among inflammation, aging, and CMH development are not well-defined. In the current study, we hypothesized that the pathogenesis of inflammation-induced CMH in mice differs by age.

Methods

We studied young (3 months, n = 20) and old (18 months, n = 25) C57BL/6 mice injected with low-dose lipopolysaccharide (LPS; 1 mg/kg, i.p.) or saline at 0, 6, and 24 h. Seven days after the first LPS/saline injection, brains were harvested, sectioned, and stained with hematoxylin and eosin (H&E) and Prussian blue (PB) to estimate acute/fresh and sub-acute CMH development, respectively. The relationships between microglial/macrophage activation (ionized calcium-binding adapter molecule-1), astrocyte activation (glial fibrillary acidic protein), blood-brain barrier (BBB) disruption (brain immunoglobulin G), aging, and CMH development were examined using immunohistochemistry.

Results

Aging alone did not increase spontaneous H&E-positive CMH development but significantly increased the number, size, and total area of LPS-induced H&E-positive CMH in mice. LPS- and saline-treated aged mice had significantly larger PB-positive CMH compared with young mice, but the total area of PB-positive CMH was increased only in LPS-treated aged mice. Aged mice had significantly increased microglial/macrophage activation, which correlated with H&E- and PB-positive CMH development. Aged mice treated with LPS had significantly increased astrocyte activation and BBB disruption compared with young LPS-treated mice.

Conclusions

Aging makes the brain more susceptible to inflammation-induced CMH in mice, and this increase in CMH with aging is associated with microglial/macrophage activation.

Abstract TP187: 24-hour Ambulatory Blood Pressure, Cognitive Performance, and Cerebral Microbleeds in the Elderly

Introduction: Multiple studies suggest a role for blood pressure (BP) variability and nocturnal BP dipping in the development of cerebrovascular disease and cognitive impairment. We analyzed cross-sectional data from a cohort of 90+ year-olds to test the hypothesis that BP variables are associated with cognitive function and cerebral microbleeds (CMB).

Methods: Study subjects were 121 participants (mean age = 93 years, 63% female) in The 90+ Study , a study of aging in individuals aged 90 years and older from a California retirement community. Participants were given a neuropsychological test battery to determine cognitive status. All subjects underwent 24-hour ambulatory BP measurement with a automatic device. MRI scans were available for 26 participants. Over three time frames (24-hour, daytime, nighttime) and separately for SBP and DBP, we represented BP by mean, minimum, maximum, standard deviation (SD), coefficient of variation, average real variability, percentage of high measurements (≥140 mmHg for SBP and ≥90 mmHg for DBP), percentage of low measurements (<90 mmHg for SBP and <60 mmHg for DBP), and nocturnal dip (% change of mean night BP from mean day BP). Differences in means of BP variables between groups based on cognitive status (normal vs cognitively impaired not demented (CIND)/demented) and presence/absence of CMB were tested using t-tests.

Results: Cognitive status was normal in 97 subjects, CIND/demented in 24. Mean nocturnal dips (both SBP and DBP) differed significantly between the two groups, with normal participants having on average greater dip levels (6.6 vs 1.3, p=0.006 for SBP and 11 vs 4.4, p=0.002 for DBP). No other BP variable showed a large or significant difference. Greater nocturnal dips were also related to better performance on cognitive test scores related to language, recent memory, and visual-spatial ability. MRI findings showed subjects with CMB (n=18) had higher SD of daytime SBP than those without (n=8) (20 vs 16, p=0.03). Those with CMB also had a greater proportion of high nighttime DBP (≥90 mmHg) readings (3.6 vs 0, p=0.03).

Conclusions: Among 90+ year olds, altered nocturnal BP dipping may have a role in cognitive impairment, while SBP variation and diastolic hypertension may contribute to development of microbleeds.

Lower likelihood of falling at age 90+ is associated with daily exercise a quarter of a century earlier: The 90+ Study

Objective

to explore the relationship between risk of falling at age 90+ and prior physical activity at age 60-70s.

Design

population-based cohort study (The 90+ Study).

Setting

California retirement community.

Participants

of 1596 cohort members, 1536 had both falls and prior activity data. Mean age = 94 years; 78% female; 99% Caucasian.

Methods

time spent in active physical activity was self-reported in 1980s; medical history, medication, assistive devices, residence type, and falls (outcome) was collected in 2000s. Activity/fall relationships were assessed using logistic regression.

Results

falls were reported by 52% of participants, recurrent falls by 32%, and severe injury by 21% of fallers. In univariate analyses risk of falling at age 90+ was significantly related to medical history (heart disease, TIA/stroke, arthritis, vision disease, depression, dementia), medication use (hypnotics, anti-psychotics, anti-depressants), use of assistive devices (cane, walker, wheelchair), residence type (living with relatives, sheltered living), and source of information (self-report vs informant). Risks of falling and recurrent falls at age 90+ were 35-45% lower in those reporting 30+ minutes/day of active physical activity at age 60-70s compared with no activity. The odds ratio of falling was 0.65 (95% CI = 0.44-0.97) for 30-45 minutes/day and 0.64 (0.44-0.94) for 1+ hour/day adjusting for age, sex, medical history (stroke/TIA, vision disease, depression), use of assistive devices, and source of information.

Conclusions and Relevance

falls are extremely common among the oldest-old and a significant proportion lead to severe injury. This work is the first to show an association between exercise at age 60-70s and lower risk of falling at age 90+.

Histological Characteristics of Intracranial Atherosclerosis in a Chinese Population: A Postmortem Study

Background

Anterior and posterior circulation atherosclerosis differ in vascular risk factors and stroke mechanisms. However, few studies have compared the pathological features between these lesions. Using a series of intracranial artery specimens, we characterized the intracranial atherosclerotic lesions and compared pathological features among different arteries of the intracranial vasculature.

Methods

Intracranial large arteries of 32 consecutively recruited autopsy cases of Chinese adults aged 45 years or older were examined pathologically using routine histology and immunostaining, to characterize the pathological features of the atherosclerotic lesions. We analyzed middle cerebral arteries (MCAs) (both left and right), vertebral arteries (VAs) (side more affected), and basilar arteries (BAs).

Results

Progressive atherosclerotic lesions were present in 91(71%) of the 128 arteries examined. Features of complicated plaques were infrequently detected: plaque hemorrhage was encountered in 12%, neovasculature in 12%, lumen thrombi in 13%, macrophage infiltration in 20%, and calcification in 25% of arteries. Luminal narrowing of MCA was the most severe, followed by VA; the BA least stenotic (37 ± 25 vs. 30 ± 24 vs. 20 ± 20%, all p < 0.05). MCA had more eccentric (vs. concentric) plaques than VA (69 vs. 25%, p = 0.003) and BA (69 vs. 38%; p = 0.03). Lumen thrombi were more frequent in BA, and calcification most commonly occurred in VA atherosclerotic lesions.

Conclusion

Intracranial atherosclerotic plaques were commonly present in this sample, but the lesions generally lacked features of complicated plaques. MCA lesions had demonstrable differences compared with VA and BA lesions. Further studies are needed to determine whether these characteristics indicate a distinctive atherosclerotic phenotype for the intracranial vasculature.

Effects of phosphodiesterase 3A modulation on murine cerebral microhemorrhages

BACKGROUND

Cerebral microbleeds (CMB) are MRI-demonstrable cerebral microhemorrhages (CMH) which commonly coexist with ischemic stroke. This creates a challenging therapeutic milieu, and a strategy that simultaneously protects the vessel wall and provides anti-thrombotic activity is an attractive potential approach. Phosphodiesterase 3A (PDE3A) inhibition is known to provide cerebral vessel wall protection combined with anti-thrombotic effects. As an initial step in the development of a therapy that simultaneously treats CMB and ischemic stroke, we hypothesized that inhibition of the PDE3A pathway is protective against CMH development.

METHODS

The effect of PDE3A pathway inhibition was studied in the inflammation-induced and cerebral amyloid angiopathy (CAA)-associated mouse models of CMH. The PDE3A pathway was modulated using two approaches: genetic deletion of PDE3A and pharmacological inhibition of PDE3A by cilostazol. The effects of PDE3A pathway modulation on H&E- and Prussian blue (PB)-positive CMH development, BBB function (IgG, claudin-5, and fibrinogen), and neuroinflammation (ICAM-1, Iba-1, and GFAP) were investigated.

RESULTS

Robust development of CMH in the inflammation-induced and CAA-associated spontaneous mouse models was observed. Inflammation-induced CMH were associated with markers of BBB dysfunction and inflammation, and CAA-associated spontaneous CMH were associated primarily with markers of neuroinflammation. Genetic deletion of the PDE3A gene did not alter BBB function, microglial activation, or CMH development, but significantly reduced endothelial and astrocyte activation in the inflammation-induced CMH mouse model. In the CAA-associated CMH mouse model, PDE3A modulation via pharmacological inhibition by cilostazol did not alter BBB function, neuroinflammation, or CMH development.

CONCLUSIONS

Modulation of the PDE3A pathway, either by genetic deletion or pharmacological inhibition, does not alter CMH development in an inflammation-induced or in a CAA-associated mouse model of CMH. The role of microglial activation and BBB injury in CMH development warrants further investigation.

Cerebral Microbleeds, Hypertension, and Intracerebral Hemorrhage in Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy

Background

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common genetic cause of stroke. In addition to ischemic stroke, CADASIL predisposes to development of cerebral microbleeds (CMB). CMB and hypertension are known to be associated with intracerebral hemorrhage (ICH). The purpose of this study was to analyze the relationships among CMB, hypertension, and ICH in CADASIL.

Materials and methods

We enrolled 94 genetically confirmed CADASIL patients from 76 unrelated families at Jeju National University Hospital (Korea) between March 2012 and February 2015. We analyzed CMB presence, number, and distribution on susceptibility-weighted imaging MRI using the microbleed anatomical rating scale. Multiple logistic regression was used to determine factors associated with the presence of CMB and ICH.

Results

CMB were observed in 62 patients (66%), median number of CMB per patient was 4 (range 0–121). Twenty-two ICHs were found in 16 patients (17%). There was incongruence between the most common site of CMB (thalamus) and that of ICH (basal ganglia). Hypertension was independently associated with the presence of CMB (multiple regression OR, 2.71; 95% CI 1.02–7.18, p < 0.05), and CMB ≥ 9 (highest third) was significantly associated with the presence of ICH (multiple regression OR = 9.50, 95% CI 1.08–83.71, p < 0.05).

Conclusion

In this CADASIL sample, presence of hypertension was independently associated with CMB presence, and CMB burden was independently associated with ICH. Incongruence of sites for CMB and ICH is currently unexplained and requires further study.

Abstract WMP75: Age- and Sex-Specific Development of Cerebral Microbleeds in a Mouse Model

Cerebral microbleeds (CMB), a common MRI finding that may predict intracerebral hemorrhage, are based on a pathological substrate of cerebral microhemorrhages (CMH). Recent clinical and laboratory studies have demonstrated the importance of systemic inflammation in the development of CMB. The effects of age and sex on CMB development have not been well-defined. In the current study, we hypothesized that there are age and sex differences in the pathogenesis of inflammation-induced CMB in mice. We studied young (3 months, n=39) and old (17 months, n=25) male and female C57BL/6 mice injected with LPS (1mg/kg, i.p.) or saline at 0, 6, and 24h. 7 days after first LPS injection, cardiac perfusion was performed, mice were sacrificed, and brains were harvested. CMH grossly visible on the brain surface were examined and 40 μm brain sections were prepared and stained with hematoxylin and eosin (H&E) to estimate the acute/fresh parenchymal CMH number, size and total area in young versus old mice. No surface CMH and negligible H&E-positive parenchymal CMH were observed in young and old saline controls. LPS treatment significantly (p<0.001) increased the development of surface CMH in aged male mice (mean±SEM=17±6 surface microhemorrhages/brain) compared to young male mice (2.8±1.5 surface microhemorrhages/brain). Negligible H&E-positive CMH were observed in LPS-treated young mice. Aging increased the number (1.3±0.7 vs 0.09±0.05 CMH/section; p<0.05), size (4510±1431 vs 471±188 μm 2 ; p<0.001) and area (0.03±0.02 vs 0.0005±0.0003 % total area; p<0.01) of H&E-positive parenchymal CMH in old LPS-treated male mice compared to young LPS-treated male mice. Consistent with previous studies from our lab, H&E-positive CMH were predominantly located in the cerebellum compared to the cortex and sub-cortex. No significant differences were observed in LPS-induced surface or parenchymal CMH development between young and aged female mice. In summary, effects of aging on LPS-induced microbleed development are demonstrable in males. Aging makes the brain more susceptible to inflammation-induced cerebral microbleeds in male mice.

Age of onset of hypertension and risk of dementia in the oldest-old: The 90+ Study

INTRODUCTION

We investigated the association between age of onset of hypertension and dementia risk in an oldest-old cohort.

METHODS

Participants are from The 90+ Study, a population-based longitudinal study of people aged 90+ who are survivors from the Leisure World Cohort Study. We estimated hypertension onset age using self-reported information from The 90+ Study and Leisure World Cohort Study, collected about 20 years earlier. A total of 559 participants without dementia were followed every 6 months for up to 10 years.

RESULTS

A total of 224 participants developed dementia during follow-up (mean = 2.8 years). Compared with those without hypertension, participants whose hypertension onset age was 80 to 89 years had a lower dementia risk (hazard ratio = 0.58, P = .04) and participants with an onset age of 90+ years had the lowest risk (hazard ratio = 0.37, P = .004).

DISCUSSION

Developing hypertension at older ages may protect against dementia. Understanding the mechanisms for this lower risk is important for determining ways to prevent dementia in the very elderly.

A murine model of inflammation-induced cerebral microbleeds

BACKGROUND

Cerebral microhemorrhages (CMH) are tiny deposits of blood degradation products in the brain and are pathological substrates of cerebral microbleeds. The existing CMH animal models are β-amyloid-, hypoxic brain injury-, or hypertension-induced. Recent evidence shows that CMH develop independently of hypoxic brain injury, hypertension, or amyloid deposition and CMH are associated with normal aging, sepsis, and neurodegenerative conditions. One common factor among the above pathologies is inflammation, and recent clinical studies show a link between systemic inflammation and CMH. Hence, we hypothesize that inflammation induces CMH development and thus, lipopolysaccharide (LPS)-induced CMH may be an appropriate model to study cerebral microbleeds.

METHODS

Adult C57BL/6 mice were injected with LPS (3 or 1 mg/kg, i.p.) or saline at 0, 6, and 24 h. At 2 or 7 days after the first injection, brains were harvested. Hematoxylin and eosin (H&E) and Prussian blue (PB) were used to stain fresh (acute) hemorrhages and hemosiderin (sub-acute) hemorrhages, respectively. Brain tissue ICAM-1, IgG, Iba1, and GFAP immunohistochemistry were used to examine endothelium activation, blood-brain barrier (BBB) disruption, and neuroinflammation. MRI and fluorescence microscopy were used to further confirm CMH development in this model.

RESULTS

LPS-treated mice developed H&E-positive (at 2 days) and PB-positive (at 7 days) CMH. No surface and negligible H&E-positive CMH were observed in saline-treated mice (n = 12). LPS (3 mg/kg; n = 10) produced significantly higher number, size, and area of H&E-positive CMH at 2 days. LPS (1 mg/kg; n = 9) produced robust development of PB-positive CMH at 7 days, with significantly higher number and area compared with saline (n = 9)-treated mice. CMH showed the highest distribution in the cerebellum followed by the sub-cortex and cortex. LPS-induced CMH were predominantly adjacent to cerebral capillaries, and CMH load was associated with indices of brain endothelium activation, BBB disruption, and neuroinflammation. Fluorescence microscopy confirmed the extravasation of red blood cells into the brain parenchyma, and MRI demonstrated the presence of cerebral microbleeds.

CONCLUSIONS

LPS produced rapid and robust development of H&E-positive (at 2 days) and PB-positive (at 7 days) CMH. The ease of development of both H&E- and PB-positive CMH makes the LPS-induced mouse model suitable to study inflammation-induced CMH.

Definition and Implications of the Preventable Stroke

IMPORTANCE

Although patients with acute stroke are routinely evaluated for potential treatment (ie, treatability of the stroke), preventability of the presenting stroke is generally not seriously considered.

OBJECTIVE

To systematically analyze stroke preventability.

DESIGN, SETTING, AND PARTICIPANTS

We evaluated medical records of 274 consecutive patients discharged with a diagnosis of ischemic stroke between December 2, 2010, and June 11, 2012, at the University of California Irvine Medical Center. Mean (SE) patient age was 67.2 (0.8) years. Data analysis was conducted from July 3, 2014, to August 4, 2015.

EXPOSURES

Medical records were systematically examined for demographic information, stroke risk factors, stroke severity, and acute stroke treatment.

MAIN OUTCOMES AND MEASURES

We defined stroke preventability as the degree to which the patient's presenting stroke was preventable. Using variables easily determined at onset of stroke, we developed a 10-point scale (0, not preventable; 10, most preventable) to classify the degree of stroke preventability. Our focus was effectiveness of treatment of hypertension (0-2 points), hyperlipidemia (0-2 points), and atrial fibrillation (0-4 points), as well as use of antithrombotic treatment for known prior cerebrovascular and cardiovascular disease (0-2 points).

RESULTS

Total risk scores ranged from 0 to 8 (mean [SE], 2.2 [0.1]), with 207 patients (75.5%) exhibiting some degree of preventability (score of 1 or higher). Seventy-one patients (25.9%) had scores of 4 or higher, indicating that the stroke was highly preventable. Severity of stroke as determined by the National Institutes of Health Stroke Scale score was not related to preventability of stroke. However, 21 of 71 patients (29.6%) whose stroke was highly preventable were treated with intravenous or intra-arterial acute stroke therapy while these treatments were provided for only 13 of 67 patients (19.4%) with scores of 0 (no preventability) and 19 of 136 patients (14.0%) with scores of 1 to 3 (low preventability) (P = .03).

CONCLUSIONS AND RELEVANCE

Most patients with acute stroke exhibited some degree of preventability. Preventability and treatment of stroke were significantly associated, indicating that the most preventable strokes paradoxically were more likely to receive acute treatment.

Impact of interventions to reduce Alzheimer's disease pathology on the prevalence of dementia in the oldest-old

INTRODUCTION

The number of persons aged >90 years will grow significantly in coming decades. This group has the highest rates of dementia, most commonly Alzheimer's disease (AD).

METHODS

Using The 90+ Study, we developed a statistical model for dementia risk based on brain pathologies. Intervention scenarios which reduce or eliminate AD pathology were considered, and the numbers of dementia cases among the U.S. oldest-old that could be prevented were estimated.

RESULTS

The U.S. dementia prevalence among the oldest-old will increase from 1.35 million in 2015 to 4.72 million in 2050. If interventions eliminate AD pathology, dementia prevalence would be reduced by approximately 50%, averting nearly 2.4 million cases in 2050. However, large numbers of dementia cases would still remain.

DISCUSSION

Reducing AD pathology would significantly decrease the public health burden of dementia. However, other interventions are needed to address the burden associated with other dementing pathologies prevalent in the oldest-old.

Abstract 215: A Systemic Inflammation-Induced Mouse Model of Cerebral Microbleeds

Introduction: Cerebral microhemorrhages (CMH) are tiny deposits of blood degradation products in the brain and are the pathological substrate of cerebral microbleeds (MB). The existing animal models of MB are either β-amyloid-, anti-amyloid antibody-, or hypertension-induced; however, MB may develop independent of hypertension or amyloid deposition. In fact, MB are associated with normal aging, sepsis and neurodegenerative conditions. One common factor among the above pathologies is inflammation, and recent studies show a link between systemic inflammation and MB. Hence, we hypothesize that systemic inflammation (induced by lipopolysaccharide; LPS) will result in MB development, and an inflammation-induced animal model will be appropriate to study MB. In the current study we used two different dosing regimens for LPS and observed rapid and robust development of CMH and MB.

Methods: Adult C57BL/6 mice were injected with LPS (1mg/kg or 3mg/kg, i.p.) or saline at 0, 6, and 24h. At 2 or 7 days after first LPS injection, brains were harvested. Hematoxylin and eosin (H&E) and Prussian blue (PB) were used to stain fresh (acute) hemorrhages and hemosiderin (subacute hemorrhages), respectively.

Results: No surface and negligible H&E-positive CMH were observed in saline controls (n=4). LPS (3mg/kg; n=13) resulted in significantly higher number (p<0.01), size (p<0.05) and area (p<0.01) of H&E-positive CMH at 2 days. Negligible PB-positive CMH were observed at 2 days after LPS (3 or 1 mg/kg) injection. However, LPS (1mg/kg) resulted in robust development of PB-positive CMH at 7 days, with significantly higher number (p<0.05), size (p<0.05) and area (p<0.01) in LPS (n=9) versus saline (n=4) treated mice. MRI confirmed the presence of MB in this model. The number of CMH was significantly higher in the cerebellum (p<0.05) compared to cortical or subcortical regions.

Conclusion: In summary, LPS produced rapid development of H&E-positive CMH (at 2 and 7 days) and PB-positive CMH (at 7 days) with low mortality. Thus, this appears to be an appropriate model to study the pathophysiology of CMH and MB.

Left atrial septal pouch in cryptogenic stroke

Background: The left atrial septal pouch (LASP), an anatomic variant of the interatrial septum, has uncertain clinical significance. We examined the association between LASP and ischemic stroke subtypes in patients undergoing transesophageal echocardiography (TEE).

Methods: We determined the prevalence of LASP among consecutive patients who underwent TEE at our institution. Patients identified with ischemic strokes were further evaluated for stroke subtype using standard and modified criteria from the Trial of Org 10172 in Acute Stroke Treatment (TOAST). We compared the prevalence of LASP in ischemic stroke, cryptogenic stroke, and non-stroke patients using prevalence ratios (PR).

Results: The mean age of all 212 patients (including stroke and non-stroke patients) was 57 years. The overall prevalence of LASP was 17% (n = 35). Of the 75 patients who were worked-up for stroke at our institution during study period, we classified 31 as cryptogenic using standard TOAST criteria. The prevalence of LASP among cryptogenic stroke patients (using standard and modified TOAST criteria) was increased compared to the prevalence among other ischemic stroke patients (26 vs. 9%, p = 0.06; PR = 1.8, 95% CI = 1.1–3.1, and 30 vs. 10%, p = 0.04; PR = 2.2, 95% CI = 1.2–4.1, respectively).

Conclusion: In this population of relatively young patients, prevalence of LASP was increased in cryptogenic stroke compared to stroke patients of other subtypes. These findings suggest LASP is associated with cryptogenic stroke, which should be verified by future large-scale studies.

Antioxidant vitamin intake and mortality: the Leisure World Cohort Study

To assess the relationship between antioxidant vitamin intake and all-cause mortality in older adults, we examined these associations using data from the Leisure World Cohort Study, a prospective study of residents of the Leisure World retirement community in Laguna Hills, California. In the early 1980s, participants (who were aged 44-101 years) completed a postal survey, which included details on use of vitamin supplements and dietary intake of foods containing vitamins A and C. Age-adjusted and multivariate-adjusted (for factors related to mortality in this cohort—smoking, alcohol intake, caffeine consumption, exercise, body mass index, and histories of hypertension, angina, heart attack, stroke, diabetes, rheumatoid arthritis, and cancer) hazard ratios for death were calculated using Cox regression for 8,640 women and 4,983 men (median age at entry, 74 years). During follow-up (1981-2013), 13,104 participants died (median age at death, 88 years). Neither dietary nor supplemental intake of vitamin A or vitamin C nor supplemental intake of vitamin E was significantly associated with mortality after multivariate adjustment. A compendium that summarizes previous findings of cohort studies evaluating vitamin intake and mortality is provided. Attenuation in the observed associations between mortality and antioxidant vitamin use after adjustment for confounders in our study and in previous studies suggests that such consumption identifies persons with other mortality-associated lifestyle and health risk factors.

Effects of PDE4 Pathway Inhibition in Rat Experimental Stroke

PURPOSE: The first genomewide association study indicated that variations in the phosphodiesterase 4D (PDE4D) gene confer risk for ischemic stroke. However, inconsistencies among the studies designed to replicate the findings indicated the need for further investigation to elucidate the role of the PDE4 pathway in stroke pathogenesis. Hence, we studied the effect of global inhibition of the PDE4 pathway in two rat experimental stroke models, using the PDE4 inhibitor rolipram. Further, the specific role of the PDE4D isoform in ischemic stroke pathogenesis was studied using PDE4D knockout rats in experimental stroke. METHODS: Rats were subjected to either the ligation or embolic stroke model and treated with rolipram (3mg/kg; i.p.) prior to the ischemic insult. Similarly, the PDE4D knockout rats were subjected to experimental stroke using the embolic model. RESULTS: Global inhibition of the PDE4 pathway using rolipram produced infarcts that were 225% (p<0.01) and 138% (p<0.05) of control in the ligation and embolic models, respectively. PDE4D knockout rats subjected to embolic stroke showed no change in infarct size compared to wild-type control. CONCLUSIONS: Despite increase in infarct size after global inhibition of the PDE4 pathway with rolipram, specific inhibition of the PDE4D isoform had no effect on experimental stroke. These findings support a role for the PDE4 pathway, independent of the PDE4D isoform, in ischemic stroke pathogenesis. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Comparative analysis of H&E and Prussian blue staining in a mouse model of cerebral microbleeds

Cerebral microbleeds are microscopic hemorrhages with deposits of blood products in the brain, which can be visualized with MRI and are implicated in cerebrovascular diseases. Hematoxylin and eosin (H&E) and Perl's Prussian blue are popular staining methods used to localize cerebral microbleeds in pathology. This paper compared these two staining techniques in a mouse model of cerebral microbleeds. We used lipopolysaccharide (LPS) to induce cerebral microhemorrhages. C57B6 mice were treated with LPS (5 mg/kg, i.p.) or vehicle at baseline and at 24 hr. The brains were extracted 48 hr after the first injection and adjacent coronal sections were stained with H&E and Prussian blue to compare the effectiveness of the two staining techniques. H&E-positive stains were increased with LPS treatment and were correlated with grossly visible microhemorrhages on the brain surface; Prussian blue-positive stains, by comparison, showed no significant increase with LPS treatment and did not correlate with either H&E-positive stains or surface microhemorrhages. H&E staining is thus a more reliable indicator of acute bleeding events induced by LPS in this model within a short time span.

Abstract W MP94: Acute Inflammation Expands Cerebral Microbleeds in a Mouse Model of Cerebral Amyloid Angiopathy

Introduction: Cerebral microscopic hemorrhages are the pathologic substrate of cerebral microbleeds (CMB). Little is known about mechanisms of expansion of CMB. Here we studied the dynamics of CMB after acute inflammation, using a transgenic mouse model of cerebral amyloid angiopathy with spontaneous microscopic hemorrhages and endotoxin (lipopolysaccharide, LPS) as an inflammatory stimulus.

Methods: 21-month old Tg2576 mice and wildtype littermates received a single dose of LPS, 100 or 1000 ug/kg i.p., or phosphate-buffered saline (PBS) as control. Mice were sacrificed 48 hours later and brains were collected for the analysis of microscopic hemorrhages, as well as edema formation, blood-brain barrier constituents and glial activation. Differences among groups were tested by anova and contrasts.

Results: Hematoxylin and eosin staining demonstrated no freshly-formed microscopic hemorrhages in LPS-treated mice. Using Prussian blue staining, we found that total area, average size, and number of CMB differed significantly between PBS-treated wildtype and transgenic mice (p=0.03, p=.04 and p=.03 respectively). Acute inflammation did not significantly affect total area, average size, or number of CMB in wildtype animals. For transgenic mice, both doses of LPS significantly (p<.01) increased the total area of Prussian blue-positive lesions (2.2 to 2.9-fold increase), and higher LPS dose significantly (p<.01) increased average size of CMB by 2.6-fold; both average and total size of CMB increased in a dose-dependent manner. IgG and fibrinogen levels significantly increased after high dose LPS injection in both wildtype and transgenic mice (p<.05). Tight junction protein claudin-5 levels were also increased in high dose LPS-treated mice (p<0.05). LPS injection significantly increased expression of activated microglia markers CD45, CD14, and Iba1.

Conclusions: In a mouse model of cerebral amyloid angiopathy, acute inflammatory stimulus induced expansion of CMB without producing fresh hemorrhage. Increased size of CMB was associated with indices of cerebral edema, alteration of tight junction constituents, and microglial activation. These findings suggest that cerebral edema may mediate expansion of cerebral microbleeds.

Responders versus nonresponders in a dementia study of the oldest old: the 90+ study

Because of difficulties in finding, recruiting, and diagnosing dementia in the oldest old (ages ≥90 years), most incidence studies include few very elderly persons, and little is known about the characteristics of those who refuse participation. In a California longitudinal study of dementia and aging (The 90+ Study, 2003-2011), we compared nonresponders with responders with regard to information collected 20 years earlier and the impression of dementia as determined during telephone recruitment. Of 1,815 eligible subjects, 1,514 (83%) joined the study, 182 refused, and 119 could not be contacted. Responders did not differ from nonresponders by sex or previously collected medical history or lifestyle behaviors. Recruiters' impressions of dementia were similar in responders and nonresponders who refused (35% and 38%), and among responders, impressions of dementia showed high positive predictive value (95%) but low sensitivity (51%) for a diagnosis of dementia made during the study. Although epidemiologic studies among the very old have the potential for significant nonresponse bias due to a high proportion of frail, ill, and cognitively impaired persons, strategies can improve response rates to over 80%. Classifying nonresponders on cognitive ability at recruitment, though crude, will give some idea of the selective bias in dementia prevalence and incidence estimates introduced by nonresponse due to cognitive status.

Aging in Place in a Retirement Community: 90+ Year Olds

Aging in place, an image of growing old in one's home and maintaining one's daily routine, is desired by most older adults. To identify variables promoting such independent living in the oldest-old, we examined the association between living situation of a population-based cohort of 90+ year olds with health and lifestyle variables. Of 1485 participants, 53% still lived in their home at a retirement community designed to foster wellness. Those living at home tended to be healthier, with smaller proportions having chronic diseases or hospitalizations in the preceding year and a greater proportion having normal functional ability. Dementia was the chronic disease most significantly related to living situation. In addition to not having dementia, not using a wheelchair or bath aid, receiving meals on wheels, and being married were jointly related to living at home. With the help of family and friends and with a medical and social support system, many 90+ year olds can age in place. This is often because they have a caregiving spouse or paid caregiver.

Apolipoprotein E genotype, dementia, and mortality in the oldest old: the 90+ Study

BACKGROUND

Although the apolipoprotein E (APOE) ε4 allele is a major genetic risk factor for Alzheimer's disease (AD), it is not clear whether this relationship persists among the oldest old. Several European studies suggest that the effect of the APOE ε4 allele on dementia and mortality disappears in very old age. We describe the APOE allele and genotype frequencies and examine whether the presence of the APOE ε4 or APOE ε2 alleles is related to prevalent dementia, incident dementia, and mortality in a population-based cohort of oldest-old participants in the United States.

METHODS

We studied 904 participants aged 90 years and older from The 90+ Study. Eight hundred two (89%) participants were genotyped and included in the prevalent dementia and mortality analyses. The 520 initially nondemented participants were included in the incident dementia analyses and were evaluated for dementia every 6 months.

RESULTS

The APOE ε4 allele was significantly associated with prevalent dementia (odds ratio = 2.06) and AD (odds ratio = 2.37) in women but not in men. The APOE ε2 allele was not related to prevalent dementia in either sex. After an average follow-up of 2.4 years, 188 incident dementia cases were identified. Neither the APOE ε4 nor the APOE ε2 allele was related to incident dementia or AD. Five hundred ten (64%) participants died after an average follow-up of 2.3 years, and their mortality was not related to the presence of either the APOE ε2 or APOE ε4 allele.

CONCLUSIONS

Our findings suggest that the associations between APOE ε4, dementia, and mortality are age dependent, and that APOE ε4 no longer plays a role in dementia and mortality at very old ages.

Dentition, dental health habits, and dementia: the Leisure World Cohort Study

OBJECTIVES

To explore the association between dentition and dental health behaviors and incident dementia.

DESIGN

Longitudinal cohort.

SETTING

Leisure World, Laguna Hills, CA; a retirement community.

PARTICIPANTS

Five thousand four hundred sixty-eight older (median age 81) adults followed from 1992 to 2010.

MEASUREMENTS

Questions regarding dental health focused on number of natural teeth, dentures worn, number of visits to a dentist, and oral health habits. Dementia status was determined from in-person evaluations, follow-up questionnaires, hospital data, and death certificates. Estimates of dementia risk were calculated using Cox regression analysis in men and women separately.

RESULTS

Men with inadequate natural masticatory function who did not wear dentures had a 91% greater risk of dementia than those with adequate natural masticatory function (≥ 10 upper teeth and ≥ 6 lower teeth). This risk was also greater in women but not significantly so. Dentate individuals who reported not brushing their teeth daily had a 22% to 65% greater risk of dementia than those who brushed three times daily.

CONCLUSION

In addition to helping maintain natural, healthy, functional teeth, oral health behaviors are associated with lower risk of dementia in older adults.