Definition of the contribution of an Osteopontin-producing CD11c+ microglial subset to Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of incurable dementia and represents a critical public health issue as the world's population ages. Although microglial dysregulation is a cardinal feature of AD, the extensive heterogeneity of these immunological cells in the brain has impeded our understanding of their contribution to this disease. Here, we identify a pathogenic microglial subset which expresses the CD11c surface marker as the sole producer of Osteopontin (OPN) in the 5XFAD mouse model of AD. OPN production divides Disease-Associated Microglia (DAM) into two functionally distinct subsets, i.e., a protective CD11c+OPN- subset that robustly ingests amyloid ß (Aß) in a noninflammatory fashion and a pathogenic CD11c+OPN+ subset that produces proinflammatory cytokines and fails to ingest significant amounts of Aß. Genetic ablation of OPN or administration of monoclonal anti-OPN antibody to 5XFAD mice reduces proinflammatory microglia, plaque formation, and numbers of dystrophic neurites and results in improved cognitive function. Analysis of brain tissue from AD patients indicates that levels of OPN-producing CD11c+ microglia correlate strongly with the degree of cognitive deficit and AD neuropathology. These findings define an OPN-dependent pathway to disease driven by a distinct microglial subset, and identify OPN as a novel therapeutic target for potentially effective immunotherapy to treat AD.

Behavioral and Brain Correlates of Emotional Distress in Older Adults During COVID-19 Quarantine.

COVID-19 led to unprecedented lockdowns and changes in older adults' lives, especially those with type 2 diabetes who have high risk of complications and mortality. We investigated the associations of cognitive and motor function and gray matter volumes (GMVs) with COVID-19 lockdown-related emotional distress of type 2 diabetes older adults, participating in the Israel Diabetes and Cognitive Decline Study. We administered a questionnaire to obtain information about anxiety, depression, general well-being, and optimism during a mandated lockdown. Lower grip strength before lockdown was associated with increased sadness, anxiety, and less optimism. Slower gait speed was associated with greater sadness. Lower GMV was related to greater anxiety during the lockdown when compared with anxiety levels before the COVID-19 outbreak. Yet, global cognition was not associated with any emotional distress measure. These results support the role of good motor function on emotional well-being during acute stress and GMV as a potential underlying mechanism.

Engagement of vascular early response genes typifies mild cognitive impairment.

INTRODUCTION: Molecular responses in the brains of persons with mild cognitive impairment (MCI), the earliest transitional state between normal aging and early Alzheimer's disease (AD), are poorly understood. METHODS: We examined AD-related neuropathology and transcriptome changes in the neocortex of individuals with MCI relative to controls and temporal responses to the mild hypoxia in mouse brains. RESULTS: Subsets of vascular early response to hypoxia genes were upregulated in MCI prior to the buildup of AD neuropathology. Early activation of pro-angiogenic hypoxia-inducible factor signaling in response to mild hypoxia was detected in mouse brains similar to those that were altered in MCI. Protracted responses to hypoxia were characterized by activation of phosphoinositide 3-kinase (PI3K)-protein kinase B (Akt)-the mammalian target of rapamycin (mTOR) pathways in brain microvessel isolates. DISCUSSION: These findings suggest that cerebrovascular remodeling is an important antecedent to the development of dementia and a component of the homeostatic response to reduced oxygen tension in aging prior to the onset of AD.

Higher BMI is associated with smaller regional brain volume in older adults with type 2 diabetes.

AIMS/HYPOTHESIS: There are established relationships between adiposity (obesity) and higher dementia risk, faster cognitive decline and associated neural injury. Type 2 diabetes is strongly linked to greater adiposity and has been consistently associated with neural injury and poor cognitive outcomes. However, although obesity is a major cause of type 2 diabetes, there is limited evidence on the association of adiposity with brain atrophy among individuals with type 2 diabetes. METHODS: We examined the association of BMI (a measure of adiposity), and of long-term trajectories of BMI (three empirically identified groups of trajectories-'normal', 'overweight' and 'obese'-using SAS macro PROC TRAJ), with regional brain volume, in a sample of older individuals (aged 64-84) with type 2 diabetes participating in the Israel Diabetes and Cognitive Decline Study (n = 198). RESULTS: Using linear regression, we found that greater BMI was associated with smaller volumes of the inferior frontal gyrus (IFG) (r = -0.25, p = 0.001) and the middle temporal gyrus (r = -0.19; p = 0.010) after adjusting for sociodemographic covariates and total intracranial volume. In addition, there were significant differences between BMI trajectory groups in IFG volume (F = 4.34, p = 0.014), such that a long-term trajectory of obesity was associated with a smaller volume. Additional adjustment for cardiovascular and diabetes-related potential confounders did not substantively alter the results. There were no associations of adiposity with superior frontal gyrus, middle frontal gyrus or total grey matter volumes. CONCLUSIONS/INTERPRETATION: In older adults with type 2 diabetes, long-term adiposity may have a detrimental impact on volume of brain regions relevant to cognitive functioning. Further studies to identify the underlying mechanisms are warranted. Graphical abstract.

Caspase-1 has a critical role in blood-brain barrier injury and its inhibition contributes to multifaceted repair.

BACKGROUND: Excessive inflammation might activate and injure the blood-brain barrier (BBB), a common feature of many central nervous system (CNS) disorders. We previously developed an in vitro BBB injury model in which the organophosphate paraoxon (PX) affects the BBB endothelium by attenuating junctional protein expression leading to weakened barrier integrity. The objective of this study was to investigate the inflammatory cellular response at the BBB to elucidate critical pathways that might lead to effective treatment in CNS pathologies in which the BBB is compromised. We hypothesized that caspase-1, a core component of the inflammasome complex, might have important role in BBB function since accumulating evidence indicates its involvement in brain inflammation and pathophysiology. METHODS: An in vitro human BBB model was employed to investigate BBB functions related to inflammation, primarily adhesion and transmigration of peripheral blood mononuclear cells (PBMCs). Caspase-1 pathway was studied by measurements of its activation state and its role in PBMCs adhesion, transmigration, and BBB permeability were investigated using the specific caspase-1 inhibitor, VX-765. Expression level of adhesion and junctional molecules and the secretion of pro-inflammatory cytokines were measured in vitro and in vivo at the BBB endothelium after exposure to PX. The potential repair effect of blocking caspase-1 and downstream molecules was evaluated by immunocytochemistry, ELISA, and Nanostring technology. RESULTS: PX affected the BBB in vitro by elevating the expression of the adhesion molecules E-selectin and ICAM-1 leading to increased adhesion of PBMCs to endothelial monolayer, followed by elevated transendothelial-migration which was ICAM-1 and LFA-1 dependent. Blocking caspase-8 and 9 rescued the viability of the endothelial cells but not the elevated transmigration of PBMCs. Inhibition of caspase-1, on the other hand, robustly restored all of barrier insults tested including PBMCs adhesion and transmigration, permeability, and VE-cadherin protein levels. The in vitro inflammatory response induced by PX and the role of caspase-1 in BBB injury were corroborated in vivo in isolated blood vessels from hippocampi of mice exposed to PX and treated with VX-765. CONCLUSIONS: These results shed light on the important role of caspase-1 in BBB insult in general and specifically in the inflamed endothelium, and suggest therapeutic potential for various CNS disorders, by targeting caspase-1 in the injured BBB.

Long-term trajectories of BMI predict carotid stiffness and plaque volume in type 2 diabetes older adults: a cohort study.

BACKGROUND: High body mass index (BMI) is a risk factor for type 2 diabetes and cardiovascular disease. However, its relationships with indices of carotid stiffness and plaque volume are unclear. We investigated associations of long-term measurements of BMI with indices of carotid stiffness and atherosclerosis among non-demented diabetes patients from the Israel Diabetes and Cognitive Decline (IDCD) study. METHODS: Carotid ultrasound indices [carotid intima media thickness (cIMT), distensibility, elastography and plaque volume] were assessed in N = 471 participants. Mean BMI across all MHS diabetes registry measurements and trajectories of BMI were calculated. BMI was categorized into three trajectory groups representing: a relatively stable normal weight (n = 185, 44%), overweight trajectory (n = 188, 44.8%) and a trajectory of obesity (n = 47, 11.2%). Linear and logistic regressions estimated associations of carotid indices with mean BMI and BMI trajectories. RESULTS: Compared to the normal weight trajectory, an obesity trajectory was associated with carotid distensibility (ß = - 3.078, p = 0.037), cIMT (ß = 0.095, p = 0.004), and carotid elastography (ß = 0.181, p = 0.004) but not with plaque volume (ß = 0.066, p = 0.858). Compared with the normal weight trajectory, an obesity trajectory was associated with increased odds for impaired carotid distensibility (OR = 2.790, p = 0.033), impaired cIMT (OR = 5.277, p = 0.001) and large carotid plaque volume (OR = 8.456, p = 0.013) but not with carotid elastography (OR = 1.956, p = 0.140). Mean BMI was linearly associated with Distensibility (ß = - 0.275, p = 0.005) and cIMT (ß = 0.005, p = 0.026). CONCLUSIONS: Long-term measurements of adiposity are associated with indices of carotid stiffness and plaque volume among older type 2 diabetes adults.

C-reactive protein in midlife is associated with depressive symptoms two decades later among men with coronary heart disease.

Aim: We investigated the relationship between midlife C-reactive protein (CRP) levels in men with coronary heart disease (CHD) and depressive symptoms at old age. CRP levels were measured in a subset of patients with CHD, who previously participated in a secondary prevention trial.Methods: Depressive symptoms were evaluated in survivors of the original cohort 15.0 ± 3 and 19.9 ± 1 years later (T1, n = 463 and T2, n = 314 respectively) using the Geriatric Depression Scale (GDS), 15-item version. Logistic regression was used to estimate ORs and 95%CIs for presence of potentially clinically significant depressive symptoms (GDS ≥5) at T1 and T2.Results: Adjusting for demographic and health-related variables, the OR (95%CI) for GDS ≥5 was 1.23 (0.65-2.33); p = .53 at T1 and 2.36 (1.16-4.83); p = .018 at T2 in the top CRP tertile compared to the others. Similarly, consistently high CRP levels in the top tertile at baseline and 2 years later, were associated with OR of 2.85 (95%CI 1.29-6.30); p = .01 for GDS ≥5 at T2.Conclusions: Presence and persistence of low-grade inflammation in men with CHD during midlife are associated with increased risk of depressive symptoms twenty years later. Among middle aged men with CHD, low-grade inflammation may provide an important added value for prediction of depression in old age.

Personality traits and cognitive function in old-adults with type-2 diabetes.

Objectives: Personality may constitute an important domain of influence on cognitive function in old-adults. We assessed the relationship of personality traits and cognitive performance in individuals with Type-2 Diabetes (T2D), and explored possible mediators. Method: The sample includes 377 dementia-free subjects with T2D participating in the Israel Diabetes and Cognitive Decline study who underwent assessment of cognition and personality (mean age 72 ± 4y; 42% females). We assessed the relationships of personality traits with episodic memory, semantic categorization, attention/working memory, executive function and overall cognition using linear regression models adjusting for age, education, sex, BMI, T2D duration, Hemoglobin A1C (HbA1C), hypertension, c-reactive protein, total- to HDL-cholesterol ratio and ApoEɛ4 genotype. A post-hoc mediation analysis was conducted with HbA1C, proportion of days covered (PDC) by T2D prescription claims and depressive symptoms. Results: After adjustment for multiple covariates, high neuroticism levels were associated with poorer performance overall (ß= -0.16 ± 0.05; p = 0.001) and with poorer episodic memory, attention/working memory, and semantic categorization (ß= -0.14 ± 0.05; p = 0.007, ß= -0.12 ± 0.05; p = 0.017 and ß= -0.12 ± 0.05; p = 0.018, respectively). High scores on openness to experience were associated with better global cognition (ß = 0.11 ± 0.05; p = 0.026), executive functions (ß = 0.13 ± 0.05; p = 0.013) and semantic categorization (ß = 0.17 ± 0.05; p = 0.001, respectively). Depressive symptoms mediated the association of neuroticism with executive function, and the association of openness with executive function and overall cognition. Conclusion: Personality may play an important role in cognitive health among elderly subjects with T2D. Future studies should address the mechanisms underlying these relationships and specifically the potential role of depressive symptoms which may be in the causal pathway between personality traits and cognitive outcomes.

Depression in type 1 diabetes and risk of dementia.

OBJECTIVE: Depression afflicts 14% of individuals with type 1 diabetes (T1D). Depression is a robust risk factor for dementia but it is unknown if this holds true for individuals with T1D, who recently started living to an age conferring dementia risk. We examined if depression is a dementia risk factor among elderly individuals with T1D. METHODS: 3,742 individuals with T1D age ≥50 were followed for dementia from 1/1/96-9/30/2015. Depression, dementia, and comorbidities were abstracted from electronic medical records. Cox proportional hazard models estimated the association between depression and dementia adjusting for demographics, glycosylated hemoglobin, severe dysglycemic epidsodes, stroke, heart disease, nephropathy, and end stage renal disease. The cumulative incidence of dementia by depression was estimated conditional on survival dementia-free to age 55. RESULTS: Five percent (N = 182) were diagnosed with dementia and 20% had baseline depression. Depression was associated with a 72% increase in dementia (fully adjusted HR = 1.72; 95% CI:1.12-2.65). The 25-year cumulative incidence of dementia was more than double for those with versus without depression (27% vs. 12%). CONCLUSIONS: For people with T1D, depression significantly increases dementia risk. Given the pervasiveness of depression in T1D, this has major implications for successful aging in this population recently living to old age.

Oral glycotoxins are a modifiable cause of dementia and the metabolic syndrome in mice and humans.

Age-associated dementia and Alzheimer's disease (AD) are currently epidemic. Neither their cause nor connection to the metabolic syndrome (MS) is clear. Suppression of deacetylase survival factor sirtuin 1 (SIRT1), a key host defense, is a central feature of AD. Age-related MS and diabetes are also causally associated with suppressed SIRT1 partly due to oxidant glycotoxins [advanced glycation end products (AGEs)]. Changes in the modern diet include excessive nutrient-bound AGEs, such as neurotoxic methyl-glyoxal derivatives (MG). To determine whether dietary AGEs promote AD, we evaluated WT mice pair-fed three diets throughout life: low-AGE (MG(-)), MG-supplemented low-AGE (MG(+)), and regular (Reg) chow. Older MG(+)-fed mice, similar to old Reg controls, developed MS, increased brain amyloid-ß42, deposits of AGEs, gliosis, and cognitive deficits, accompanied by suppressed SIRT1, nicotinamide phosphoribosyltransferase, AGE receptor 1, and PPARγ. These changes were not due to aging or caloric intake, as neither these changes nor the MS were present in age-matched, pair-fed MG(-) mice. The mouse data were enhanced by significant temporal correlations between high circulating AGEs and impaired cognition, as well as insulin sensitivity in older humans, in whom dietary and serum MG levels strongly and inversely associated with SIRT1 gene expression. The data identify a specific AGE (MG) as a modifiable risk factor for AD and MS, possibly acting via suppressed SIRT1 and other host defenses, to promote chronic oxidant stress and inflammation. Because SIRT1 deficiency in humans is both preventable and reversible by AGE reduction, a therapeutic strategy that includes AGE reduction may offer a new strategy to combat the epidemics of AD and MS.

Ethnicity/culture modulates the relationships of the haptoglobin (Hp) 1-1 phenotype with cognitive function in older individuals with type 2 diabetes.

OBJECTIVE: The haptoglobin (Hp) genotype has been associated with cognitive function in type 2 diabetes. Because ethnicity/culture has been associated with both cognitive function and Hp genotype frequencies, we examined whether it modulates the association of Hp with cognitive function. METHODS: This cross-sectional study evaluated 787 cognitively normal older individuals (>65 years of age) with type 2 diabetes participating in the Israel Diabetes and Cognitive Decline study. Interactions in two-way analyses of covariance compared Group (Non-Ashkenazi versus Ashkenazi Jews) on the associations of Hp phenotype (Hp 1-1 versus non- Hp 1-1) with five cognitive outcome measures. The primary control variables were age, gender, and education. RESULTS: Compared with Ashkenazi Jews, non-Ashkenazi Jews with the Hp 1-1 phenotype had significantly poorer cognitive function than non-Hp 1-1 in the domains of Attention/Working Memory (p = 0.035) and Executive Function (p = 0.023), but not in Language/Semantic Categorization (p = 0.432), Episodic Memory (p = 0.268), or Overall Cognition (p = 0.082). After controlling for additional covariates (type 2 diabetes-related characteristics, cardiovascular risk factors, Mini-mental State Examination, and extent of depressive symptoms), Attention/Working Memory (p = 0.038) and Executive Function (p = 0.013) remained significant. CONCLUSIONS: Older individuals from specific ethnic/cultural backgrounds with the Hp 1-1 phenotype may benefit more from treatment targeted at decreasing or halting the detrimental effects of Hp 1-1 on the brain. Future studies should examine differential associations of Hp 1-1 and cognitive impairment, especially for groups with high prevalence of both, such as African-Americans and Hispanics.

Waist circumference is correlated with poorer cognition in elderly type 2 diabetes women.

INTRODUCTION: Waist circumference is associated with type 2 diabetes (T2D) and cognition, yet the relationship between waist circumference and cognition in individuals with T2D is not well understood. METHODS: We studied the relationship of waist circumference with five cognitive outcomes (executive functioning, language/semantic categorization, attention/working memory, episodic memory, and an overall cognition measure) in 845 cognitively normal elderly with type 2 diabetes (T2D). RESULTS: In women, waist circumference was correlated with significantly lower language and/or semantic categorization performance (P < .0001), executive functioning (P = .026), and overall cognition (P = .003) after controlling for age, education, BMI, and cardiovascular, diabetes-related, APOE ε4, and inflammatory potential confounders. Attention/working memory (P = .532) and episodic memory (P = .144) were not associated with waist circumference. These correlations were not found in men. DISCUSSION: These results suggest that central adiposity in elderly women with T2D may increase their risk for dementia.

Differences Between Tg2576 and Wild Type Mice in the NMDA Receptor-Nitric Oxide Pathway After Prolonged Application of a Diet High in Advanced Glycation End Products.

It has been suggested that advanced glycation end (AGE) products, via cognate receptor activation, are implicated in several diseases, including Alzheimer's disease. The NMDA receptor-nitric oxide pathway appears to be influenced by AGE products and involved in the pathogenesis of this type of dementia. In this study, C57BL/6J (WT) and transgenic (Tg2576) mice expressing human mutant amyloid precursor protein were kept on prolonged (8 months) diets containing regular or high amounts of AGE products. After the decapitation of 11-months old mice, brain tissue analyses were performed [expressions of the NR1, NR2A and NR2B subunits of NMDA receptors, activities of neuronal, endothelial and inducible nitric oxide synthase (nNOS, eNOS and iNOS)]. Moreover, levels of malondialdehyde and of human amyloid ß 1-42 were estimated. We found increased activity of nNOS in WT mice maintained on a high compared to regular AGE diet; however, no similar differences were found in Tg2576 mice. In addition, we observed an increase in NR1 expression in Tg2576 compared to WT mice, both kept on a diet high in AGE products. Correlation analyses performed on mice kept on the regular AGE diet supported close links between particular subunits (NR2A-NR2B, in WT as well as in Tg2576 mice), between subunits and synthase (NR2A/NR2B-nNOS, only in WT mice) or between particular synthases (nNOS-iNOS, only in WT). Correlation analysis also revealed differences between WT mice kept on both diets (changed correlations between NR2A/NR2B-nNOS, between nNOS-eNOS and between eNOS-iNOS). Malondialdehyde levels were increased in both Tg2576 groups when compared to the corresponding WT mice, but no effects of the diets were observed. Analogously, no significant effects of diets were found in the levels of soluble or insoluble amyloid ß 1-42 in Tg2576 mice. Our results demonstrate that prolonged ingestion of AGE products can influence the NMDA receptor-nitric oxide pathway in the brain and that only WT mice, not Tg2576 mice, are able to maintain homeostasis among subunits and synthases or among particular synthases. The prolonged application of AGE products enhanced differences between 11-months old Tg2576 and WT mice regarding this pathway. Observed differences in the pathway between WT mice kept on regular or high AGE diets suggest that the prolonged application of a diet low in AGE products could have beneficial effects in older or diabetic people and perhaps also in people with Alzheimer's disease.

Glycemic control, inflammation, and cognitive function in older patients with type 2 diabetes.

OBJECTIVE: Glycated hemoglobin (HbA1c) and C-reactive protein (CRP) have been associated with cognitive impairment independently. However, it is unclear if their combination exacerbates poor cognitive function. We assessed whether long-term glycemic level and glycemic variability modulate the association of systemic inflammation with cognitive function, in a sample of cognitively normal older people with type 2 diabetes. METHODS: A retrospective cohort study of 777 randomly selected participants from ~11,000 patients in the Maccabi Healthcare Services Diabetes Registry, as part of the Israel Diabetes and Cognitive Decline study. Subjects averaged 18 (±9.4) HbA1c measures in the Maccabi Healthcare Services Registry, which were used to calculate long-term glycemic level (HbA1c-mean) and glycemic variability (HbA1c-standard deviation (SD)). Linear regression models assessed the interactions of CRP, a marker of systemic inflammation, with HbA1c-mean and HbA1c-SD on subjects' performance in tests of Memory, Executive Functions, Attention, and Semantic Categorization. RESULTS: Quadratic interactions of CRP with HbA1c-SD approached significance for executive functions and overall cognition. However, after Bonferroni adjustment, none of the interactions of CRP with HbA1c were statistically significant. In partial correlations according to HbA1c-SD tertiles, CRP was weakly correlated in the middle tertile with decreased performance in the domains of semantic categorization (r = -0.166, p = 0.011), executive functions (r = -0.136, p = 0.038), and overall cognition (r = -0.157, p = 0.016). CONCLUSIONS: Glycated hemoglobin does not substantially modulate the association of CRP with cognition in a sample of cognitively normal, community dwelling older people with relatively well-managed type 2 diabetes.

The association of duration of type 2 diabetes with cognitive performance is modulated by long-term glycemic control.

OBJECTIVES: It is unclear why duration of type 2 diabetes (T2D) is associated with increased cognitive compromise. High hemoglobin A1c (HbA1c) has also been associated with dementia, and is the primary contributor to T2D complications. Here we investigated whether the association of duration of T2D with cognitive functioning is modulated by HbA1C levels. METHODS: This study examined nondemented community-dwelling T2D elderly (N = 897) participating in the Israel Diabetes and Cognitive Decline study, who were assessed with a broad neuropsychological battery. Subjects were all from the Maccabi Healthcare Services, which has a Diabetes Registry with complete HbA1c measurements since 1998. Partial correlations were performed to examine the modulating effect of HbA1c on the relationship of duration of T2D with five cognitive measures, controlling for sociodemographic and cardiovascular risk factors. RESULTS: An interaction of duration of T2D with HbA1c was associated with executive functioning (p = 0.006), semantic categorization (p = 0.019), attention/working memory (p = 0.011), and overall cognition (p = 0.006), such that the associations between duration of T2D and cognitive impairment increased as HbA1c levels increased-but not for episodic memory (p = 0.984). CONCLUSIONS: Because duration of T2D was associated with cognition in higher HbA1c levels and overall no associations were found in lower HbA1c levels, our results suggest that individuals with T2D may limit their risk of future cognitive decline by maintaining long-term good glycemic control.

Age, gender, and education are associated with cognitive performance in an older Israeli sample with type 2 diabetes.

OBJECTIVE: To evaluate the relationships of age, education, and gender with performance on neuropsychological tests in a cognitively intact, older Israeli sample with type 2 diabetes (T2D). METHODS: We examined 862 participants, 65-84 years old, enrolled in the Israel Diabetes and Cognitive Decline study. Multiple regression assessed associations of performance on 17 neuropsychological tests, including the Consortium to Establish a Registry for Alzheimer's Disease neuropsychological battery, with age, education, and gender. RESULTS: Higher education and younger age were consistently associated with better performance. Women outperformed men on all memory tasks; men outperformed women on two non-verbal measures. These patterns of demographic associations with cognitive performance were very similar to those of US cohorts. CONCLUSIONS: In a cognitively intact, older Israeli sample with T2D, better test performance is associated primarily with higher education, followed by younger age and gender differences. Although T2D is associated with cognitive deficits, it recapitulates the patterns of relationships between cognitive performance and demographic characteristics seen in non-T2D diabetic samples.

Assessment of verbal memory in Parkinson's disease utilizing a virtual reality-based Rey Auditory Verbal Learning Test.

The Rey Auditory Verbal Learning Test (RAVLT) is a commonly used tool for evaluating verbal learning and memory in neuropsychological assessments. In recent years, we developed a Virtual Reality (VR) adaptation of the RAVLT (VR-RVLT), aiming for increased ecological validity compared to the traditional pen and paper gold standard (GS-RAVLT). Following validation in healthy cohorts, the VR-RAVLT was validated with thirty individuals with Parkinson's Disease (PD) that completed both the GS-RAVLT and the VR- RAVLT. Validity of the VR-RAVLT was evaluated by assessing its construct and discriminant validity, and test-retest reliability, in comparison to the GS-RAVLT. Results of the PD participants were compared to those of 46 previously recruited healthy participants with comparable age and level of education. Main outcome measures derived from the remembered items on the test lists, exhibited significant and comparable correlations between VR-RAVLT and GS-RAVLT, both among healthy participants and PD participants. Likewise, serial position effects were similar for both formats amog the PD participants. Additionally, both formats showed similar discriminatory ability between healthy controls and PD participants, as well as comparable test-retest reliability measures. Taken together, the results suggest that the VR-based RAVLT is equally effective in measuring verbal memory capabilities in individuals with PD as compared to the GS-RAVLT. Certain results indicate that the virtual reality version has the capability to encompass additional factors that might impact memory performance, thereby suggesting an enhanced ecological validity.

Application of Delayed Contrast Extravasation Magnetic Resonance Imaging for Depicting Subtle Blood-Brain Barrier Disruption in a Traumatic Brain Injury Model.

The blood-brain barrier (BBB) is composed of brain microvasculature that provides selective transport of solutes from the systemic circulation into the central nervous system to protect the brain and spinal microenvironment. Damage to the BBB in the acute phase after traumatic brain injury (TBI) is recognized as a major underlying mechanism leading to secondary long-term damage. Because of the lack of technological ability to detect subtle BBB disruption (BBBd) in the chronic phase, however, the presence of chronic BBBd is disputable. Thus, the dynamics and course of long-term BBBd post-TBI remains elusive. Thirty C57BL/6 male mice subjected to TBI using our weight drop closed head injury model and 19 naïve controls were scanned by magnetic resonance imaging (MRI) up to 540 days after injury. The BBB maps were calculated from delayed contrast extravasation MRI (DCM) with high spatial resolution and high sensitivity to subtle BBBd, enabling depiction and quantification of BBB permeability. At each time point, 2-6 animals were sacrificed and their brains were extracted, sectioned, and stained for BBB biomarkers including: blood microvessel coverage by astrocyte using GFAP, AQP4, ZO-1 gaps, and IgG leakage. We found that DCM provided depiction of subtle yet significant BBBd up to 1.5 years after TBI, with significantly higher sensitivity than standard contrast-enhanced T1-weighted and T2-weighted MRI (BBBd volumes main effect DCM/T1/T2 p < 0.0001 F(2,70) = 107.3, time point p < 0.0001 F(2,133, 18.66) = 23.53). In 33% of the cases, both in the acute and chronic stages, there was no detectable enhancement on standard T1-MRI, nor detectable hyperintensities on T2-MRI, whereas DCM showed significant BBBd volumes. The BBBd values of TBI mice at the chronic stage were found significantly higher compared with age matched naïve animals at 30, 60, and 540 days. The calculated BBB maps were histologically validated by determining significant correlation between the calculated levels of disruption and a diverse set of histopathological parameters obtained from different brain regions, presenting different components of the BBB. Cumulative evidence from recent years points to BBBd as a central component of the pathophysiology of TBI. Therefore, it is expected that routine use of highly sensitive non-invasive techniques to measure BBBd, such as DCM with advanced analysis methods, may enhance our understanding of the changes in BBB function after TBI. Application of the DCM technology to other CNS disorders, as well as to normal aging, may shed light on the involvement of chronic subtle BBBd in these conditions.

Glycoproteome-Wide Discovery of Cortical Glycoproteins That May Provide Cognitive Resilience in Older Adults.

BACKGROUND AND OBJECTIVES: Molecular omics studies have identified proteins related to cognitive resilience but unrelated to Alzheimer disease and Alzheimer disease-related dementia (AD/ADRD) pathologies. Posttranslational modifications of proteins with glycans can modify protein function. In this study, we identified glycopeptiforms associated with cognitive resilience. METHODS: We studied brains from adults with annual cognitive testing with postmortem indices of 10 AD/ADRD pathologies and proteome-wide data from dorsal lateral prefrontal cortex (DLPFC). We quantified 11, 012 glycopeptiforms from DLPFC using liquid chromatography with tandem mass spectrometry. We used linear mixed-effects models to identify glycopeptiforms associated with cognitive decline correcting for multiple comparisons (p < 5 × 10-6). Then, we regressed out the effect of AD/ADRD pathologies to identify glycopeptiforms that may provide cognitive resilience. RESULTS: We studied 366 brains, average age at death 89 years, and 70% female with no cognitive impairment = 152, mild cognitive impairment = 93, and AD = 121 cognitive status at death. In models adjusting for age, sex and education, 11 glycopeptiforms were associated with cognitive decline. In further modeling, 8 of these glycopeptiforms remained associated with cognitive decline after adjusting for AD/ADRD pathologies: NPTX2a (Est., 0.030, SE, 0.005, p = 1 × 10-4); NPTX2b (Est.,0.019, SE, 0.005, p = 2 × 10-4) NECTIN1(Est., 0.029, SE, 0.009, p = 9 × 10-4), NPTX2c (Est., 0.015, SE, 0.004, p = 9 × 10-4), HSPB1 (Est., -0.021, SE, 0.006, p = 2 × 10-4), PLTP (Est., -0.027, SE, 0.009, p = 4.2 × 10-3), NAGK (Est., -0.027, SE, 0.008, p = 1.4 × 10-3), and VAT1 (Est., -0.020, SE, 0.006, p = 1.1 × 10-3). Higher levels of 4 resilience glycopeptiforms derived through glycosylation were associated with slower decline and higher levels of 4 derived through glycation were related to faster decline. Together, these 8 glycopeptiforms accounted for an additional 6% of cognitive decline over the 33% accounted for the 10 brain pathologies and demographics. All 8 resilience glycopeptiforms remained associated with cognitive decline after adjustments for the expression level of their corresponding protein. Exploratory gene ontology suggested that molecular mechanisms of glycopeptiforms associated with cognitive decline may involve metabolic pathways including pyruvate and NADH pathways and highlighted the importance of molecular mechanisms involved in glucose metabolism. DISCUSSION: Glycopeptiforms in aging brains may provide cognitive resilience. Targeting these glycopeptiforms may lead to therapies that maintain cognition through resilience.

Abdominal fat depots are related to lower cognitive functioning and brain volumes in middle-aged males at high Alzheimer's risk.

OBJECTIVE: High BMI, which poorly represents specific fat depots, is linked to poorer cognition and higher dementia risk, with different associations between sexes. This study examined associations of abdominal fat depots with cognition and brain volumes and whether sex modifies this association. METHODS: A total of 204 healthy middle-aged offspring of Alzheimer's dementia patients (mean age = 59.44, 60% females) underwent abdominal magnetic resonance imaging to quantify hepatic, pancreatic, visceral, and subcutaneous adipose tissue and to assess cognition and brain volumes. RESULTS: In the whole sample, higher hepatic fat percentage was associated with lower total gray matter volume (ß = -0.17, p < 0.01). Primarily in males, higher pancreatic fat percentage was associated with lower global cognition (males: ß = -0.27, p = 0.03; females: ß = 0.01, p = 0.93) executive function (males: ß = -0.27, p = 0.03; females: ß = 0.02, p = 0.87), episodic memory (males: ß = -0.28, p = 0.03; females: ß = 0.07, p = 0.48), and inferior frontal gyrus volume (males: ß = -0.28, p = 0.02; females: ß = 0.10, p = 0.33). Visceral and subcutaneous adipose tissue was inversely associated with middle frontal and superior frontal gyrus volumes in males and females. CONCLUSIONS: In middle-aged males at high Alzheimer's dementia risk, but not in females, higher pancreatic fat was associated with lower cognition and brain volumes. These findings suggest a potential sex-specific link between distinct abdominal fat with brain health.