Mercury and selenium distribution in human brain tissue using synchrotron micro-X-ray fluorescence

Mercury is a well-recognized environmental contaminant and neurotoxin, having been associated with a number of deleterious neurological conditions including neurodegenerative diseases, such as Alzheimer's disease. To investigate how mercury and other metals behave in the brain, we used synchrotron micro-X-ray fluorescence to map the distribution pattern and quantify concentrations of metals in human brain. Brain tissue was provided by the Rush Alzheimer's Disease Center and samples originated from individuals diagnosed with Alzheimer's disease and without cognitive impairment. Data were collected at the 2-ID-E beamline at the Advanced Photon Source at Argonne National Laboratory with an incident beam energy of 13 keV. Course scans were performed at low resolution to determine gross tissue features, after which smaller regions were selected to image at higher resolution. The findings revealed (1) the existence of mercury particles in the brain samples of two subjects; (2) co-localization and linear correlation of mercury and selenium in all particles; (3) co-localization of these particles with zinc structures; and (4) association with sulfur in some of these particles. These results suggest that selenium and sulfur may play protective roles against mercury in the brain, potentially binding with the metal to reduce the induced toxicity, although at different affinities. Our findings call for further studies to investigate the relationship between mercury, selenium, and sulfur, as well as the potential implications in Alzheimer's disease and related dementias.

Genetic associations with dementia-related proteinopathy: Application of item response theory

INTRODUCTION

Although dementia-related proteinopathy has a strong negative impact on public health, and is highly heritable, understanding of the related genetic architecture is incomplete.

METHODS

We applied multidimensional generalized partial credit modeling (GPCM) to test genetic associations with dementia-related proteinopathies. Data were analyzed to identify candidate single nucleotide variants for the following proteinopathies: Aβ, tau, α-synuclein, and TDP-43.

RESULTS

Final included data comprised 966 participants with neuropathologic and WGS data. Three continuous latent outcomes were constructed, corresponding to TDP-43-, Aβ/Tau-, and α-synuclein-related neuropathology endophenotype scores. This approach helped validate known genotype/phenotype associations: for example, TMEM106B and GRN were risk alleles for TDP-43 pathology; and GBA for α-synuclein/Lewy bodies. Novel suggestive proteinopathy-linked alleles were also discovered, including several (SDHAF1, TMEM68, and ARHGEF28) with colocalization analyses and/or high degrees of biologic credibility.

DISCUSSION

A novel methodology using GPCM enabled insights into gene candidates for driving misfolded proteinopathies.

HIGHLIGHTS

Latent factor scores for proteinopathies were estimated using a generalized partial credit model. The three latent continuous scores corresponded well with proteinopathy severity. Novel genes associated with proteinopathies were identified. Several genes had high degrees of biologic credibility for dementia risk factors.

Evaluating genomic signatures of aging in brain tissue as it relates to Alzheimer's disease

Telomere length (TL) attrition, epigenetic age acceleration, and mitochondrial DNA copy number (mtDNAcn) decline are established hallmarks of aging. Each has been individually associated with Alzheimer's dementia, cognitive function, and pathologic Alzheimer's disease (AD). Epigenetic age and mtDNAcn have been studied in brain tissue directly but prior work on TL in brain is limited to small sample sizes and most studies have examined leukocyte TL. Importantly, TL, epigenetic age clocks, and mtDNAcn have not been studied jointly in brain tissue from an AD cohort. We examined dorsolateral prefrontal cortex (DLPFC) tissue from N = 367 participants of the Religious Orders Study (ROS) or the Rush Memory and Aging Project (MAP). TL and mtDNAcn were estimated from whole genome sequencing (WGS) data and cortical clock age was computed on 347 CpG sites. We examined dementia, MCI, and level of and change in cognition, pathologic AD, and three quantitative AD traits, as well as measures of other neurodegenerative diseases and cerebrovascular diseases (CVD). We previously showed that mtDNAcn from DLPFC brain tissue was associated with clinical and pathologic features of AD. Here, we show that those associations are independent of TL. We found TL to be associated with β-amyloid levels (beta = - 0.15, p = 0.023), hippocampal sclerosis (OR = 0.56, p = 0.0015) and cerebral atherosclerosis (OR = 1.44, p = 0.0007). We found strong associations between mtDNAcn and clinical measures of AD. The strongest associations with pathologic measures of AD were with cortical clock and there were associations of mtDNAcn with global AD pathology and tau tangles. Of the other pathologic traits, mtDNAcn was associated with hippocampal sclerosis, macroscopic infarctions and CAA and cortical clock was associated with Lewy bodies. Multi-modal age acceleration, accelerated aging on both mtDNAcn and cortical clock, had greater effect size than a single measure alone. These findings highlight for the first time that age acceleration determined on multiple genomic measures, mtDNAcn and cortical clock may have a larger effect on AD/AD related disorders (ADRD) pathogenesis than single measures.

Brain autopsies of critically ill COVID-19 patients demonstrate heterogeneous profile of acute vascular injury, inflammation and age-linked chronic brain diseases

BACKGROUND

This study examined neuropathological findings of patients who died following hospitalization in an intensive care unit with SARS-CoV-2.

METHODS

Data originate from 20 decedents who underwent brain autopsy followed by ex-vivo imaging and dissection. Systematic neuropathologic examinations were performed to assess histopathologic changes including cerebrovascular disease and tissue injury, neurodegenerative diseases, and inflammatory response. Cerebrospinal fluid (CSF) and fixed tissues were evaluated for the presence of viral RNA and protein.

RESULTS

The mean age-at-death was 66.2 years (range: 26-97 years) and 14 were male. The patient's medical history included cardiovascular risk factors or diseases (n = 11, 55%) and dementia (n = 5, 25%). Brain examination revealed a range of acute and chronic pathologies. Acute vascular pathologic changes were common in 16 (80%) subjects and included infarctions (n = 11, 55%) followed by acute hypoxic/ischemic injury (n = 9, 45%) and hemorrhages (n = 7, 35%). These acute pathologic changes were identified in both younger and older groups and those with and without vascular risk factors or diseases. Moderate-to-severe microglial activation were noted in 16 (80%) brains, while moderate-to-severe T lymphocyte accumulation was present in 5 (25%) brains. Encephalitis-like changes included lymphocytic cuffing (n = 6, 30%) and neuronophagia or microglial nodule (most prominent in the brainstem, n = 6, 30%) were also observed. A single brain showed vasculitis-like changes and one other exhibited foci of necrosis with ball-ring hemorrhages reminiscent of acute hemorrhagic leukoencephalopathy changes. Chronic pathologies were identified in only older decedents: 7 brains exhibited neurodegenerative diseases and 8 brains showed vascular disease pathologies. CSF and brain samples did not show evidence of viral RNA or protein.

CONCLUSIONS

Acute tissue injuries and microglial activation were the most common abnormalities in COVID-19 brains. Focal evidence of encephalitis-like changes was noted despite the lack of detectable virus. The majority of older subjects showed age-related brain pathologies even in the absence of known neurologic disease. Findings of this study suggest that acute brain injury superimposed on common pre-existing brain disease may put older subjects at higher risk of post-COVID neurologic sequelae.

Relationship of Purpose in Life to Dementia in Older Black and White Brazilians

OBJECTIVES

To test the hypothesis that higher level of purpose in life is associated with lower likelihood of dementia and mild cognitive impairment (MCI) in older Brazilians.

METHODS

As part of the Pathology, Alzheimer's and Related Dementias Study (PARDoS), informants of 1,514 older deceased Brazilians underwent a uniform structured interview. The informant interview included demographic data, the Clinical Dementia Rating scale to diagnose dementia and MCI, the National Institute of Mental Health Diagnostic Interview Schedule for depression, and a 6-item measure of purpose in life, a component of well-being.

RESULTS

Purpose scores ranged from 1.5 to 5.0 with higher values indicating higher levels of purpose. On the Clinical Dementia Rating Scale, 940 persons (62.1%) had no cognitive impairment, 121 (8.0%) had MCI, and 453 (29.9%) had dementia. In logistic regression models adjusted for age at death, sex, education, and race, higher purpose was associated with lower likelihood of MCI (odds ratio = .58; 95% confidence interval [CI]: .43, .79) and dementia (odds ratio = .49, 95% CI: .41, .59). Results were comparable after adjusting for depression (identified in 161 [10.6%]). Neither race nor education modified the association of purpose with cognitive diagnoses.

CONCLUSIONS

Higher purpose in life is associated with lower likelihood of MCI and dementia in older black and white Brazilians.

Multiple gene variants linked to Alzheimer's-type clinical dementia via GWAS are also associated with non-Alzheimer's neuropathologic entities

The classic pathologic hallmarks of Alzheimer's disease (AD) are amyloid plaques and neurofibrillary tangles (AD neuropathologic changes, or ADNC). However, brains from individuals clinically diagnosed with "AD-type" (amnestic) dementia usually harbor heterogeneous neuropathologies in addition to, or other than, ADNC. We hypothesized that some AD-type dementia associated genetic single nucleotide variants (SNVs) identified from large genomewide association studies (GWAS) were associated with non-ADNC neuropathologies. To test this hypothesis, we analyzed data from multiple studies with available genotype and neuropathologic phenotype information. Clinical AD/dementia risk alleles of interest were derived from the very large GWAS by Bellenguez et al. (2022) who reported 83 clinical AD/dementia-linked SNVs in addition to the APOE risk alleles. To query the pathologic phenotypes associated with variation of those SNVs, National Alzheimer's disease Coordinating Center (NACC) neuropathologic data were linked to AD Sequencing Project (ADSP) and AD Genomics Consortium (ADGC) data. Separate data were obtained from the harmonized Religious Orders Study and the Rush Memory and Aging Project (ROSMAP). A total of 4811 European participants had at least ADNC neuropathology data and also genotype data available; data were meta-analyzed across cohorts. As expected, a subset of dementia-associated SNVs were associated with ADNC risk in Europeans-e.g., BIN1, PICALM, CR1, MME, and COX7C. Other gene variants linked to (clinical) AD dementia were associated with non-ADNC pathologies. For example, the associations of GRN and TMEM106B SNVs with limbic-predominant age-related TDP-43 neuropathologic changes (LATE-NC) were replicated. In addition, SNVs in TNIP1 and WNT3 previously reported as AD-related were instead associated with hippocampal sclerosis pathology. Some genotype/neuropathology association trends were not statistically significant at P < 0.05 after correcting for multiple testing, but were intriguing. For example, variants in SORL1 and TPCN1 showed trends for association with LATE-NC whereas Lewy body pathology trended toward association with USP6NL and BIN1 gene variants. A smaller cohort of non-European subjects (n = 273, approximately one-half of whom were African-Americans) provided the basis for additional exploratory analyses. Overall, these findings were consistent with the hypothesis that some genetic variants linked to AD dementia risk exert their affect by influencing non-ADNC neuropathologies.

Dementia and autopsy-verified causes of death in racially-diverse older Brazilians

BACKGROUND

While dementia has been associated with specific causes of death, previous studies were relatively small autopsy series or population-based studies lacking autopsy confirmation and were restricted to Non-Latinx Whites. Here, we examine the association of dementia with autopsy-verified causes of death in racially-diverse older Brazilians.

METHODS

As part of the Pathology, Alzheimer´s and Related Dementias Study (PARDoS), a community-based study in Brazil, we included 1941 racially-diverse deceased, 65 years or older at death. We conducted a structured interview with legal informants including the Clinical Dementia Rating (CDR) Scale for dementia proximate to death. Causes of death were assessed after full-body autopsy and macroscopic examination of the brain, thoracic and abdominal/pelvic organs. Up to four causes of death were reported for each decedent. Causes of death were classified as circulatory, infectious, cancer and other. Logistic regression was used to determine associations of dementia with cause of death, controlling for age, sex, race, and education.

RESULTS

Dementia was associated with a higher odds of an infectious cause of death (OR = 1.81, 95%CI:1.45-2.25), and with a lower odds of a circulatory disease as cause of death (OR = 0.69, 95%CI:0.54-0.86) and cancer as cause of death (OR = 0.41, 95%CI:0.24-0.71). Dementia was associated with a higher odds of pneumonia (OR = 1.92, 95%CI:1.53-2.40) and pulmonary embolism (OR = 2.31, 95%CI:1.75-3.05) as causes of death and with a lower odds of acute myocardial infarction (OR = 0.42, 95%CI:0.31-0.56) and arterial disease (OR = 0.76, 95%CI:0.61-0.94) as causes of death.

CONCLUSION

Racially-diverse older Brazilians with dementia had a higher odds of an infectious cause of death and a lower odds of cancer and circulatory disease as causes of death than those without dementia.

Neuropsychiatric symptoms in Brazilians with mild cognitive impairment and dementia

INTRODUCTION

Knowledge is limited about behavioral and psychological symptoms of mild cognitive impairment (MCI) and dementia in racial and ethnic minorities.

METHODS

As part of the Pathology, Alzheimer's and Related Dementias Study (PARDoS), we interviewed knowledgeable informants of 2319 older Brazilian decedents (67% white, 11% black, 22% mixed) using the informant portion of the Clinical Dementia Rating Scale to classify MCI and dementia and the Neuropsychiatric Inventory to assess behavioral and psychological symptoms.

RESULTS

We identified four clusters of neuropsychiatric symptoms: agitation, affect/apathy, psychosis, and behavioral problems. On the Clinical Dementia Rating Scale, 1407 had no cognitive impairment, 180 had MCI, and 732 had dementia. Both MCI and dementia were associated with symptoms in each behavioral/psychological cluster (all P's < .001). There was little evidence of racial differences in the association of MCI and dementia with these neuropsychiatric symptoms.

CONCLUSION

MCI and dementia are associated with elevated behavioral and psychological symptoms in older black and white Brazilians.

Relation of Literacy and Music Literacy to Dementia in Older Black and White Brazilians

BACKGROUND

Literacy is more consistently reported than education as protective against dementia in developing regions.

OBJECTIVE

To study the association of verbal literacy, numeracy, and music literacy with dementia in older Black and White Brazilians with a broad spectrum of education.

METHODS

We studied 1,818 Black, Mixed-race, and White deceased Brazilians 65 years or older at death (mean = 79.64). Data were retrospectively obtained within 36 hours after death in a face-to-face interview with an informant, usually a family member. Dementia was classified using the Clinical Dementia Rating (CDR) scale. Three forms of literacy were ascertained: verbal literacy (10 questions: reading and writing), numeracy (3 questions: multiplication, percentages, and use of a calculator), and music literacy (1 question: reading music). Black (11%) and Mixed-race (23%) older adults were combined in analyses. Models adjusted for age and sex.

RESULTS

Dementia was identified in 531 people. Participants had 0 to 25 years of education (median = 4). More literacy was associated with lower odds of dementia (all p≤0.039). Participants that read music had about half the odds of having dementia. Participants in the highest quartile of numeracy and verbal literacy had respectively 27%and 15%lower odds of having dementia compared to the lowest quartile. Literacy was lower in Blacks (p < 0.001, except music p = 0.894) but the effect of literacy on dementia was similar (interaction p > 0.237). In secondary analyses, playing instruments without reading music was not associated with dementia (p = 0.887).

CONCLUSION

In a large sample of Brazilians, verbal literacy, numeracy, and music literacy were associated with lower odds of dementia. The effect was similar across races.

The link between social and emotional isolation and dementia in older black and white Brazilians

OBJECTIVE

To examine the link between social and emotional isolation and likelihood of dementia among older black and white Brazilians.

DESIGN

Cross-sectional clinical-pathological cohort study.

SETTING

Medical center in Sao Paulo, Brazil.

PARTICIPANTS

As part of the Pathology, Alzheimer's and Related Dementias Study, we conducted uniform structured interviews with knowledgeable informants (72% children) of 1,493 older (age > 65) Brazilian decedents.

MEASUREMENTS

The interview included measures of social isolation (number of family and friends in at least monthly contact with decedent), emotional isolation (short form of UCLA Loneliness Scale), and major depression plus the informant portion of the Clinical Dementia Rating Scale to diagnose dementia and its precursor, mild cognitive impairment (MCI).

RESULTS

Decedents had a median social network size of 8.0 (interquartile range = 9.0) and a median loneliness score of 0.0 (interquartile range = 1.0). On the Clinical Dementia Rating Scale, 947 persons had no cognitive impairment, 122 had MCI, and 424 had dementia. In a logistic regression model adjusted for age, education, sex, and race, both smaller network size (odds ratio [OR] = 0.975; 95% confidence interval [CI]: 0.962, 0.989) and higher loneliness (OR = 1.145; 95% CI: 1.060, 1.237) were associated with higher likelihood of dementia. These associations persisted after controlling for depression (present in 10.4%) and did not vary by race. After controlling for depression, neither network size nor loneliness was related to MCI.

CONCLUSION

Social and emotional isolation are associated with higher likelihood of dementia in older black and white Brazilians.

Neuroticism, negative life events, and dementia in older White and Black Brazilians

OBJECTIVE

Exposure to negative life events (NLEs) and neuroticism are associated with dementia. It is unknown whether neuroticism explains or modifies the association of NLEs with dementia in older Black and White Brazilians.

METHODS

A total of 1747 decedents 65 years and older White and Black (11% Black and 23% Mixed) Brazilians, 53% women, were included in the analyses. Data were obtained in a face-to-face interview with an informant (71% their children) who knew the decedents for 47 years on average. Dementia was classified using the Clinical Dementia Rating. NLEs were assessed with a 10-item scale involving common problems (e.g., death, illness, alcoholism, and financial). Neuroticism was assessed with a 6-item neuroticism scale adapted from the NEO Five-Factor Inventory. Models adjusted for age, sex, and education. Black and mixed-race were combined in the analyses.

RESULTS

NLEs (median of 2) were more common in Blacks than Whites (2.04 vs. 1.82, p = 0.007). More NLEs increased the odds of dementia (OR = 1.112, β = 0.106, p = 0.002), similarly in Blacks and Whites (β interaction  = 0.046, p = 0.526). More NLEs were also associated with higher neuroticism (β = 0.071, p < 0.0001), in Whites but not in Blacks (β interaction  = -0.048, p = 0.006). Neuroticism was associated with higher odds of dementia (OR = 1.658, β = 0.506, p=<0.001), in Whites but not in Blacks (β interaction  = -0.420, p = 0.040). Overall, 34% of the effect of NLEs on dementia was associated with the underlying neuroticism trait in Whites (65%, Indirect OR = 1.060, p < 0.001) but no association was evident in Blacks (6%, Indirect OR = 1.008, p = 0.326). Neuroticism did not moderate the association of NLEs with dementia (OR = 0.979, β = -0.021, p = 0.717).

CONCLUSION

The association of NLEs and dementia is partially explained by neuroticism in older White but not in Blacks Brazilians.

Person-Specific Contributions of Brain Pathologies to Progressive Parkinsonism in Older Adults

BACKGROUND

Mixed-brain pathologies are the most common cause of progressive parkinsonism in older adults. We tested the hypothesis that the impact of individual pathologies associated with progressive parkinsonism differs among older adults.

METHODS

Data were from 1089 decedents who had undergone annual clinical testing and autopsy. Parkinsonism was based on a modified United Parkinson's Disease Rating Scale. Linear mixed-effects models were employed, to investigate the combinations of 9 pathologies related to progressive parkinsonism. Then we estimated the person-specific contributions of each pathology for progressive parkinsonism.

RESULTS

The average participant showed 3 pathologies. Parkinson's disease (PD) and 4 cerebrovascular pathologies (macroinfarcts, atherosclerosis, arteriolosclerosis, and cerebral amyloid angiopathy [CAA]), but not Alzheimer's disease, TDP-43, hippocampal sclerosis, and microinfarcts, were independently associated with progressive parkinsonism. These pathologies accounted for 13% of additional variance of progressive parkinsonism. Thirty-one different combinations of these 5 pathologies were observed to be associated with progressive parkinsonism observed. On average, PD and CAA accounted, respectively, for 66% and 65% of person-specific progression of parkinsonism, while macroinfarcts, atherosclerosis, and arteriolosclerosis accounted for 41%-48%.

CONCLUSION

There is much greater heterogeneity in the comorbidity and relative impact of individual brain pathologies affecting progressive parkinsonism than previously recognized and this may account in part for its phenotypic heterogeneity in older adults.

Informant-Reported Discrimination, Dementia, and Cognitive Impairment in Older Brazilians

BACKGROUND

Self-reported discrimination is a source of psychosocial stress that has been previously associated with poor cognitive function in older African Americans without dementia.

OBJECTIVE

Here, we examine the association of discrimination with dementia and cognitive impairment in racially diverse older Brazilians.

METHODS

We included 899 participants 65 years or older (34.3% Black) from the Pathology, Alzheimer's and Related Dementias Study (PARDoS), a community-based study of aging and dementia. A structured interview with informants of the deceased was conducted. The interview included the Clinical Dementia Rating (CDR) Scale for the diagnosis of dementia and cognitive impairment proximate to death and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) as a second measure of cognitive impairment. Informant-reported discrimination was assessed using modified items from the Major and Everyday Discrimination Scales.

RESULTS

Discrimination was reported by informants of 182 (20.2%) decedents and was more likely reported by informants of Blacks than Whites (25.3% versus 17.6%, p = 0.006). Using the CDR, a higher level of informant-reported discrimination was associated with higher odds of dementia (OR: 1.24, 95% CI 1.08 -1.42, p = 0.002) and cognitive impairment (OR: 1.21, 95% CI: 1.06 -1.39, p = 0.004). Similar results were observed using the IQCODE (estimate: 0.07, SE: 0.02, p = 0.003). The effects were independent of race, sex, education, socioeconomic status, major depression, neuroticism, or comorbidities.

CONCLUSION

Higher level of informant-reported discrimination was associated with higher odds of dementia and cognitive impairment in racially diverse older Brazilians.

Acculturation in Context: The Relationship Between Acculturation and Socioenvironmental Factors With Level of and Change in Cognition in Older Latinos

OBJECTIVES

Latinos are 1.5 times as likely to develop Alzheimer's dementia as non-Latino Whites. This health disparity may arise from multiple influences with culturally relevant factors receiving increasing attention. Models of acculturation stress the importance of considering acculturation-related factors within the context of socioenvironmental factors to better capture the Latino experience in the United States.

METHODS

We measured 10 acculturation and contextually-related variables in 199 Latinos (age 69.7 years) without dementia participating in Rush Alzheimer's Disease Center studies. We tested the relationship between these variables via Principal Component Analysis (PCA), then investigated how resulting components associated with level of and longitudinal change in global and domain-specific cognition using separate linear mixed-effects models adjusted for relevant confounders and their interactions with time.

RESULTS

The PCA revealed a 3-factor unrotated solution (variance explained ~70%). Factor 1, representing acculturation-related aspects of nativity, language- and social-based acculturation, was positively associated with level, but not change, in global cognition, semantic memory, and perceptual speed. Factor 2, representing contextually-related socioenvironmental experiences of discrimination, social isolation, and social networks, was negatively associated with level of global cognition, episodic and working memory, and faster longitudinal decline in visuospatial ability. Factor 3 (familism only) did not associate with level or change in any cognitive outcome.

DISCUSSION

Acculturation- and contextually-related factors differentiated from each other and differentially contributed to cognition and cognitive decline in older Latinos. Providers should query acculturation and lived experiences when evaluating cognition in older Latinos.

Alzheimer's disease frequency peaks in the tenth decade and is lower afterwards

Age is the most robust risk factor for Alzheimer’s dementia, however there is little data on the relation of age to Alzheimer’s disease (AD) and other common neuropathologies that contribute to Alzheimer’s dementia. We use data from two community-based, clinical-pathologic cohorts to examine the association of age with AD and other common pathologies. Participants were 1420 autopsied individuals from the Religious Orders Study or Rush Memory and Aging Project who underwent annual clinical evaluations for diagnosis of Alzheimer’s dementia, mild cognitive impairment (MCI), and level of cognition. The neuropathologic traits of interest were pathologic AD according to modified NIA-Reagan criteria, three quantitative measures of AD pathology (global AD pathology score, β-amyloid load and PHFtau tangle density), macro- and micro-scopic infarcts, neocortical Lewy bodies, TDP-43 and hippocampal sclerosis. Semiparametric generalized additive models examined the nonlinear relationship between age and the clinical and pathological outcomes. The probability of Alzheimer’s dementia at death increased with age such that for every additional year of age, the log odds of Alzheimer’s dementia was 0.067 higher, corresponding to an odds ratio of 1.070 (p < 0.001). Results were similar for cognitive impairment and level of cognition. By contrast, a nonlinear relationship of age with multiple indices of AD pathology was observed (all ps < 0.05), such that pathologic AD reached a peak around 95 years of age and leveled off afterwards; the quantitative measures of AD pathology were significantly lower at ages above 95. The association of age with other neuropathologies was quite distinct from that of AD in that most increased with advancing age. AD pathology appears to peak around 95 years of age while other common pathologies continue to increase with age.

Morphometric measurements of systemic atherosclerosis and visceral fat: Evidence from an autopsy study

Background

Morphometric measurements of systemic atherosclerosis and direct quantification of visceral fat are only possible using materials from autopsy studies. However, the few autopsy studies that have investigated the association of visceral fat with atherosclerosis had small sample sizes and focused on coronary arteries of young or middle-aged White subjects. We aimed to investigate the association of pericardial fat (PF) and abdominal visceral fat (AVF) with atherosclerosis in the aorta, coronary, carotid, and cerebral arteries in a large autopsy study.

Materials and methods

We evaluated deceased subjects aged 30 years or above. We dissected and weighted the PF and the AVF and evaluated the atherosclerotic burden in the aorta, as well as the carotid, coronary, and cerebral arteries using morphometric measurements. We also investigated the interaction of PF and AVF with age regarding the atherosclerotic burden.

Results

The mean age of the 240 included subjects was 64.8±15.3 years, and 63% was male. Greater PF was associated with a higher degree of aortic atherosclerosis after adjusting for confounding variables (coefficient = 4.39, 95% CI = 0.83; 7.94, p = 0.02). Greater AVF was associated with a higher coronary stenosis index (coefficient = 1.49, 95% CI = 0.15; 2.83, p = 0.03) and a greater number of coronary plaques (coefficient = 0.71, 95% CI = 0.24; 1.19, p = 0.003). We did not find an association of PF or AVF with carotid or cerebral atherosclerotic burden. We found a significant interaction of AVF (coefficient = -0.08; 95% CI = -0.14; -0.02, p = 0.009) and PF (coefficient = -0.87, 95% CI = -1.70; -0.04, p = 0.04) with age regarding carotid artery atherosclerotic burden.

Conclusions

Greater AVF was associated with greater atherosclerotic burden and extent in coronary arteries, while greater PF correlated with a higher degree of atherosclerosis in the aorta.

Quantifying the accretion of hyperphosphorylated tau in the locus coeruleus and dorsal raphe nucleus: the pathological building blocks of early Alzheimer's disease

AIMS

Hyperphosphorylated tau neuronal cytoplasmic inclusions (ht-NCI) are the best protein correlate of clinical decline in Alzheimer's disease (AD). Qualitative evidence identifies ht-NCI accumulating in the isodendritic core before the entorhinal cortex. Here, we used unbiased stereology to quantify ht-NCI burden in the locus coeruleus (LC) and dorsal raphe nucleus (DRN), aiming to characterize the impact of AD pathology in these nuclei with a focus on early stages.

METHODS

We utilized unbiased stereology in a sample of 48 well-characterized subjects enriched for controls and early AD stages. ht-NCI counts were estimated in 60-μm-thick sections immunostained for p-tau throughout LC and DRN. Data were integrated with unbiased estimates of LC and DRN neuronal population for a subset of cases.

RESULTS

In Braak stage 0, 7.9% and 2.6% of neurons in LC and DRN, respectively, harbour ht-NCIs. Although the number of ht-NCI+ neurons significantly increased by about 1.9× between Braak stages 0 to I in LC (P = 0.02), we failed to detect any significant difference between Braak stage I and II. Also, the number of ht-NCI+ neurons remained stable in DRN between all stages 0 and II. Finally, the differential susceptibility to tau inclusions among nuclear subdivisions was more notable in LC than in DRN.

CONCLUSIONS

LC and DRN neurons exhibited ht-NCI during AD precortical stages. The ht-NCI increases along AD progression on both nuclei, but quantitative changes in LC precede DRN changes.

Neuropathological diagnoses and clinical correlates in older adults in Brazil: A cross-sectional study

BACKGROUND

Clinicopathological studies are important in determining the brain lesions underlying dementia. Although almost 60% of individuals with dementia live in developing countries, few clinicopathological studies focus on these individuals. We investigated the frequency of neurodegenerative and vascular-related neuropathological lesions in 1,092 Brazilian admixed older adults, their correlation with cognitive and neuropsychiatric symptoms, and the accuracy of dementia subtype diagnosis.

METHODS AND FINDINGS

In this cross-sectional study, we describe clinical and neuropathological variables related to cognitive impairment in 1,092 participants (mean age = 74 y, 49% male, 69% white, and mean education = 4 y). Cognitive function was investigated using the Clinical Dementia Rating (CDR) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE); neuropsychiatric symptoms were evaluated using the Neuropsychiatric Inventory (NPI). Associations between neuropathological lesions and cognitive impairment were investigated using ordinal logistic regression. We developed a neuropathological comorbidity (NPC) score and compared it to CDR, IQCODE, and NPI scores. We also described and compared the frequency of neuropathological diagnosis to clinical diagnosis of dementia subtype. Forty-four percent of the sample met criteria for neuropathological diagnosis. Among these participants, 50% had neuropathological diagnoses of Alzheimer disease (AD), and 35% of vascular dementia (VaD). Neurofibrillary tangles (NFTs), hippocampal sclerosis, lacunar infarcts, hyaline atherosclerosis, siderocalcinosis, and Lewy body disease were independently associated with cognitive impairment. Higher NPC scores were associated with worse scores in the CDR sum of boxes (β = 1.33, 95% CI 1.20-1.46), IQCODE (β = 0.14, 95% CI 0.13-0.16), and NPI (β = 1.74, 95% CI = 1.33-2.16). Compared to neuropathological diagnoses, clinical diagnosis had high sensitivity to AD and high specificity to dementia with Lewy body/Parkinson dementia. The major limitation of our study is the lack of clinical follow-up of participants during life.

CONCLUSIONS

NFT deposition, vascular lesions, and high NPC scorewere associated with cognitive impairment in a unique Brazilian sample with low education. Our results confirm the high prevalence of neuropathological diagnosis in older adults and the mismatch between clinical and neuropathological diagnoses.

Relation of genomic variants for Alzheimer disease dementia to common neuropathologies

OBJECTIVE

To investigate the associations of previously reported Alzheimer disease (AD) dementia genomic variants with common neuropathologies.

METHODS

This is a postmortem study including 1,017 autopsied participants from 2 clinicopathologic cohorts. Analyses focused on 22 genomic variants associated with AD dementia in large-scale case-control genome-wide association study (GWAS) meta-analyses. The neuropathologic traits of interest were a pathologic diagnosis of AD according to NIA-Reagan criteria, macroscopic and microscopic infarcts, Lewy bodies (LB), and hippocampal sclerosis. For each variant, multiple logistic regression was used to investigate its association with neuropathologic traits, adjusting for age, sex, and subpopulation structure. We also conducted power analyses to estimate the sample sizes required to detect genome-wide significance (p < 5 × 10(-8)) for pathologic AD for all variants.

RESULTS

APOE ε4 allele was associated with greater odds of pathologic AD (odds ratio [OR] 3.82, 95% confidence interval [CI] 2.67-5.46, p = 1.9 × 10(-13)), while ε2 allele was associated with lower odds of pathologic AD (OR 0.42, 95% CI 0.30-0.61, p = 3.1 × 10(-6)). Four additional genomic variants including rs6656401 (CR1), rs1476679 (ZCWPW1), rs35349669 (INPP5D), and rs17125944 (FERMT2) had p values less than 0.05. Remarkably, half of the previously reported AD dementia variants are not likely to be detected for association with pathologic AD with a sample size in excess of the largest GWAS meta-analyses of AD dementia.

CONCLUSIONS

Many recently discovered genomic variants for AD dementia are not associated with the pathology of AD. Some genomic variants for AD dementia appear to be associated with other common neuropathologies.

Association of APOE with tau-tangle pathology with and without β-amyloid

This study tested the hypothesis that the association of apolipoprotein E (APOE) with paired helical filament tau (PHF-tau) tangle pathology differs in brains with and without β-amyloid. Participants were 1056 autopsied individuals from 2 clinical-pathologic cohort studies of aging and Alzheimer's disease (AD), the Religious Orders Study, and the Rush Memory and Aging Project. Neuropathologic measures were obtained using immunohistochemistry targeting β-amyloid and PHF-tau tangles in 8 brain regions. Linear regression was used to compare the relation of APOE ε4 and ε2 to PHF-tau-tangle density in persons with β-amyloid relative to persons without β-amyloid. We found an interaction between APOE ε4 carriers and presence of β-amyloid (β = -0.968, p = 0.013) such that the association of APOE ε4 with PHF-tau tangles was much stronger in brains with β-amyloid. Stratified analysis shows that the association of APOE ε4 with PHF-tau tangles was considerably stronger among those with β-amyloid (β = 0.757, p = 1.1 × 10(-15)) compared to those without β-amyloid which was not significant (β = -0.201, p = 0.424). Separately, APOE ε2 was associated with fewer tangles in brains with β-amyloid (β = -0.425, p = 7.6 × 10(-4)) compared to those without β-amyloid which was not significant (β = -0.102, p = 0.506). Thus, the presence of APOE ε4 and ε2 alleles was not associated with PHF-tau tangles in the absence of β-amyloid. The data provide additional evidence that PHF-tau tangles in the absence of β-amyloid may reflect a pathologic process distinct from Alzheimer's disease.

APOE and cerebral amyloid angiopathy in community-dwelling older persons

Both cerebral amyloid angiopathy and Alzheimer's disease pathology involve abnormal β-amyloid processing. We aim to elucidate the relationship of the apolipoprotein E (APOE) genotypes with amyloid angiopathy in the presence of variable amounts of Alzheimer's pathology. Data came from 1062 autopsied subjects from 2 community-based studies of aging. Common neuropathologies including Alzheimer's disease and amyloid angiopathy were assessed using uniform methods. APOE was genotyped by sequencing the 2 polymorphisms in codons 112 and 158 of exon 4. We examined the associations of APOE with amyloid angiopathy using ordinal logistic regression analyses, controlling for demographics and subsequently Alzheimer's and other common pathologies. Moderate to severe amyloid angiopathy was identified in 35.2% (n = 374) of the subjects; 15.3% (n = 162) of the subjects were APOE ε2 carriers; and 26.1% (n = 277) ε4 carriers. Adjusting for demographics, the presence of ε4 allele, but not ε2, was associated with more severe amyloid angiopathy. After further adjustment for Alzheimer's pathology, both ε2 (odds ratio 1.707, 95% confidence interval 1.236-2.358, p = 0.001) and ε4 (odds ratio 2.284, 95% confidence interval 1.730-3.014, p < 0.001) were independently associated with amyloid angiopathy. The results were confirmed by path analysis. Furthermore, APOE ε4 carriers, but not ε2 carriers, were more likely to have capillary amyloid angiopathy. Accounting for capillary involvement did not alter the APOE associations with amyloid angiopathy. We conclude that both APOE ε2 and ε4 alleles are associated with more severe cerebral amyloid angiopathy, and the direct effect of ε2 is masked by the allele's negative association with comorbid Alzheimer's pathology. APOE ε4, but not ε2, is associated with capillary amyloid angiopathy.

Comprehensive geriatric assessment predicts mortality and adverse outcomes in hospitalized older adults

Background

Comprehensive Geriatric Assessment (CGA) provides detailed information on clinical, functional and cognitive aspects of older patients and is especially useful for assessing frail individuals. Although a large proportion of hospitalized older adults demonstrate a high level of complexity, CGA was not developed specifically for this setting. Our aim was to evaluate the application of a CGA model for the clinical characterization and prognostic prediction of hospitalized older adults.

Methods

This was a prospective observational study including 746 patients aged 60 years and over who were admitted to a geriatric ward of a university hospital between January 2009 and December 2011, in Sao Paulo, Brazil. The proposed CGA was applied to evaluate all patients at admission. The primary outcome was in-hospital death, and the secondary outcomes were delirium, nosocomial infections, functional decline and length of stay. Multivariate binary logistic regression was performed to assess independent factors associated with these outcomes, including socio-demographic, clinical, functional, cognitive, and laboratory variables. Impairment in ten CGA components was particularly investigated: polypharmacy, activities of daily living (ADL) dependency, instrumental activities of daily living (IADL) dependency, depression, dementia, delirium, urinary incontinence, falls, malnutrition, and poor social support.

Results

The studied patients were mostly women (67.4%), and the mean age was 80.5±7.9 years. Multivariate logistic regression analysis revealed the following independent factors associated with in-hospital death: IADL dependency (OR=4.02; CI=1.52-10.58; p=.005); ADL dependency (OR=2.39; CI=1.25-4.56; p=.008); malnutrition (OR=2.80; CI=1.63-4.83; p<.001); poor social support (OR=5.42; CI=2.93-11.36; p<.001); acute kidney injury (OR=3.05; CI=1.78-5.27; p<.001); and the presence of pressure ulcers (OR=2.29; CI=1.04-5.07; p=.041). ADL dependency was independently associated with both delirium incidence and nosocomial infections (respectively: OR=3.78; CI=2.30-6.20; p<.001 and OR=2.30; CI=1.49-3.49; p<.001). The number of impaired CGA components was also found to be associated with in-hospital death (p<.001), delirium incidence (p<.001) and nosocomial infections (p=.005). Additionally, IADL dependency, malnutrition and history of falls predicted longer hospitalizations. There were no significant changes in overall functional status during the hospital stay.

Conclusions

CGA identified patients at higher risk of in-hospital death and adverse outcomes, of which those with functional dependence, malnutrition and poor social support were foremost.

Repair of oxidative DNA damage, cell-cycle regulation and neuronal death may influence the clinical manifestation of Alzheimer's disease

Alzheimer’s disease (AD) is characterized by progressive cognitive decline associated with a featured neuropathology (neuritic plaques and neurofibrillary tangles). Several studies have implicated oxidative damage to DNA, DNA repair, and altered cell-cycle regulation in addition to cell death in AD post-mitotic neurons. However, there is a lack of studies that systematically assess those biological processes in patients with AD neuropathology but with no evidence of cognitive impairment. We evaluated markers of oxidative DNA damage (8-OHdG, H2AX), DNA repair (p53, BRCA1, PTEN), and cell-cycle (Cdk1, Cdk4, Cdk5, Cyclin B1, Cyclin D1, p27^Kip1, phospho-Rb and E2F1) through immunohistochemistry and cell death through TUNEL in autopsy hippocampal tissue samples arrayed in a tissue microarray (TMA) composed of three groups: I) “clinical-pathological AD” (CP-AD) - subjects with neuropathological AD (Braak≥IV and CERAD = B or C) and clinical dementia (CDR≥2, IQCODE>3.8); II) “pathological AD” (P-AD) - subjects with neuropathological AD (Braak≥IV and CERAD = B or C) and without cognitive impairment (CDR 0, IQCODE<3.2); and III) “normal aging” (N) - subjects without neuropathological AD (Braak≤II and CERAD 0 or A) and with normal cognitive function (CDR 0, IQCODE<3.2). Our results show that high levels of oxidative DNA damage are present in all groups. However, significant reductions in DNA repair and cell-cycle inhibition markers and increases in cell-cycle progression and cell death markers in subjects with CP-AD were detected when compared to both P-AD and N groups, whereas there were no significant differences in the studied markers between P-AD individuals and N subjects. This study indicates that, even in the setting of pathological AD, healthy cognition may be associated with a preserved repair to DNA damage, cell-cycle regulation, and cell death in post-mitotic neurons.

African ancestry protects against Alzheimer's disease-related neuropathology

Previous studies in dementia epidemiology have reported higher Alzheimer's disease rates in African-Americans when compared with White Americans. To determine whether genetically determined African ancestry is associated with neuropathological changes commonly associated with dementia, we analyzed a population-based brain bank in the highly admixed city of São Paulo, Brazil. African ancestry was estimated through the use of previously described ancestry-informative markers. Risk of presence of neuritic plaques, neurofibrillary tangles, small vessel disease, brain infarcts and Lewy bodies in subjects with significant African ancestry versus those without was determined. Results were adjusted for multiple environmental risk factors, demographic variables and apolipoprotein E genotype. African ancestry was inversely correlated with neuritic plaques (P=0.03). Subjects with significant African ancestry (n=112, 55.4%) showed lower prevalence of neuritic plaques in the univariate analysis (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.55-0.95, P=0.01) and when adjusted for age, sex, APOE genotype and environmental risk factors (OR 0.43, 95% CI 0.21-0.89, P=0.02). There were no significant differences for the presence of other neuropathological alterations. We show for the first time, using genetically determined ancestry, that African ancestry may be highly protective of Alzheimer's disease neuropathology, functioning through either genetic variants or unknown environmental factors. Epidemiological studies correlating African-American race/ethnicity with increased Alzheimer's disease rates should not be interpreted as surrogates of genetic ancestry or considered to represent African-derived populations from the developing nations such as Brazil.

Transcriptional alterations related to neuropathology and clinical manifestation of Alzheimer's disease

Alzheimer’s disease (AD) is the most common cause of dementia in the human population, characterized by a spectrum of neuropathological abnormalities that results in memory impairment and loss of other cognitive processes as well as the presence of non-cognitive symptoms. Transcriptomic analyses provide an important approach to elucidating the pathogenesis of complex diseases like AD, helping to figure out both pre-clinical markers to identify susceptible patients and the early pathogenic mechanisms to serve as therapeutic targets. This study provides the gene expression profile of postmortem brain tissue from subjects with clinic-pathological AD (Braak IV, V, or V and CERAD B or C; and CDR ≥1), preclinical AD (Braak IV, V, or VI and CERAD B or C; and CDR = 0), and healthy older individuals (Braak ≤ II and CERAD 0 or A; and CDR = 0) in order to establish genes related to both AD neuropathology and clinical emergence of dementia. Based on differential gene expression, hierarchical clustering and network analysis, genes involved in energy metabolism, oxidative stress, DNA damage/repair, senescence, and transcriptional regulation were implicated with the neuropathology of AD; a transcriptional profile related to clinical manifestation of AD could not be detected with reliability using differential gene expression analysis, although genes involved in synaptic plasticity, and cell cycle seems to have a role revealed by gene classifier. In conclusion, the present data suggest gene expression profile changes secondary to the development of AD-related pathology and some genes that appear to be related to the clinical manifestation of dementia in subjects with significant AD pathology, making necessary further investigations to better understand these transcriptional findings on the pathogenesis and clinical emergence of AD.

Delirium in hospitalized elderly patients and post-discharge mortality

OBJECTIVE

To determine the impact of delirium on post-discharge mortality in hospitalized older patients.

INTRODUCTION

Delirium is frequent in hospitalized older patients and correlates with high hospital mortality. There are only a few studies about its impact on post-discharge mortality.

METHODS

This is a prospective study of patients over 60 years old who were hospitalized in the Geriatric Unit at Hospital das Clínicas of São Paulo between May 2006 and March 2007. Upon admission, demographics, comorbidities, number of drugs taken, and serum albumin concentration were evaluated for each patient. Delirium was diagnosed according to the DSM-IV criteria. Patients were divided into group A (with delirium) and group B (without delirium). One year after discharge, the patients or their caregivers were contacted to assess days of survival.

RESULTS

The sample included 199 patients, 66 (33%) of whom developed delirium (Group A). After one year, 33 (50%) group A patients had died, and 45 (33.8%) group B patients had died (p = 0.03). There was a significant statistical difference in average age (p = 0.001) and immobility (p <0.001) between groups A and B. There were no statistically significant differences between groups A and B in number of drugs taken greater than four (p = 0.62), sex (p = 0.54) and number of diagnoses greater than four (p = 0.21). According to a multivariate analysis, delirium was not an independent predictor of post-discharge mortality. The predictors of post-discharge mortality were age > or = 80 years (p = 0.029), albumin concentration < 3.5 g/dl (p = 0.001) and immobility (p = 0.007).

CONCLUSION

Delirium is associated with higher post-discharge mortality as a dependent predictor.

The dorsal raphe nucleus shows phospho-tau neurofibrillary changes before the transentorhinal region in Alzheimer's disease. A precocious onset?

AIMS

Alzheimer's disease (AD) is a progressive and irreversible disease. There is strong evidence that the progression of the phospho-tau neurofibrillary cytoskeletal changes, rather than the beta-amyloid burden, is crucial in determining the severity of the dementia in AD. The Braak and Braak staging system (BB) focuses mainly on the cortical cytoskeletal pathology and classifies this progressive pathology into six stages, spreading from the transentorhinal region to primary cortices. Although it is reported elsewhere that the midbrain's dorsal raphe nucleus (DR), which is connected with those areas of the cerebral cortex undergoing early changes during BB I and II, exhibits AD-related cytoskeletal pathology, this nucleus has not been considered by the BB.

METHODS

To determine during which BB stage and how frequently the DR is affected by AD-related neurofibrillary changes, we studied the DR of 118 well-characterized individuals of the Brain Bank of the Brazilian Aging Brain Study Group categorized according to the BB. Thirty-eight of these individuals were staged as BB = 0, and 80 as BB >or= 1.

RESULTS

In all of the BB >or= 1 individuals (cortical neurofibrillary changes were present at least in the transentorhinal region) and in more than 1/5 of the BB = 0 individuals neurofibrillary changes were detected in the supratrochlear subnucleus of the DR.

CONCLUSIONS

These observations: (i) support the hypothesis of transneuronal spread of neurofibrillary changes from the DR to its interconnected cortical brain areas; and (ii) indicate that the supratrochlear subnucleus of the DR is affected by neurofibrillary changes before the transentorhinal cortex during the disease process underlying AD.