Changes in an in-vivo classifier of ARTerioloSclerosis (ARTS) with simultaneous change in cognition for older African Americans

At autopsy, African American decedents often have mixed Alzheimer's and cerebrovascular brain pathologies including arteriolosclerosis. We applied a novel in-vivo classifier of ARTerioloSclerosis (ARTS) in 167 older African Americans (∼75y of age) with > 2 biennial 3 T MRI scans and > 3 years of associated cognitive follow-up to determine if ARTS scores (higher score=higher likelihood of arteriolosclerosis) changed over time and if this change associated with changes in cognition in the same individuals. Mixed effects regression models tested whether ARTS scores increased over time, while simultaneous mixed effects regression models estimated the simultaneous rates of change in both ARTS and cognition and the correlation of these changes. ARTS scores increased over time (estimate=0.030, SE=0.002, p < 0.0001). Faster increases in ARTS were associated with faster rates of global cognitive decline (r = -0.447, p = 0.006) and domain-specific cognitive functions. Applying an in-vivo marker of arteriolosclerosis in an African American cohort revealed that the likelihood of arteriolosclerosis increases over time, and participants whose ARTS scores increased more rapidly tended to have faster than average rates of cognitive decline.

The Relationship of MRI-Derived Alzheimer's and Cerebrovascular-Related Signatures With Level of and Change in Health and Financial Literacy

OBJECTIVE

The cortical thickness "signature" of Alzheimer's disease (AD-CT) and white matter hyperintensity (WMH) burden have each been associated with cognitive aging and incident AD and related dementias. Less is known about how these structural neuroimaging markers associate with other critical behaviors. We investigated associations of AD-CT and WMH volumes with a composite index of health and financial literacy given that the ability to access, understand, and utilize health and financial information significantly influences older adults' health outcomes.

DESIGN, SETTING, PARTICIPANTS

Participants were 303 adults without dementia (age∼80 years; 74% women) from the Rush Memory and Aging Project.

MEASUREMENTS

Baseline 3T MRI T1-weighted structural and T2-weighted FLAIR data were used to assess AD-CT and WMH volumes, respectively. Literacy was measured using questions designed to assess comprehension of health and financial information and concepts, yielding a total literacy score. Multivariable linear mixed effects regression models determined the relationship of each neuroimaging marker, first separately and then combined, with the level of and change in literacy.

RESULTS

Reduced AD-CT and higher WMH at baseline were each associated with lower levels of literacy; only AD-CT was associated with the rate of decline in literacy over time. The association of AD-CT with change in literacy persisted when both neuroimaging markers were included in the same model.

CONCLUSIONS

The cortical thickness signature of AD predicts changes in health and financial literacy in nondemented older adults suggesting that the multidimensional construct of health and financial literacy relies on specific brain networks implicated in AD.

Late-life depressive symptoms and white matter structural integrity within older Black adults

Introduction

Older Black adults experience a high burden of depressive symptoms and cerebrovascular disease but the specific neurobiological substrates underlying the association between late-life depressive symptoms and brain integrity are understudied, particularly in within-group designs.

Methods

Using the Center for Epidemiologic Studies Depression Scale and diffusion-tensor imaging, within-Black variation in the association between late-life depressive symptoms and white matter structural integrity was examined in 297 older Black participants without dementia that were enrolled across three epidemiological studies of aging and dementia. Linear regression models were used to test associations with DTI metrics (fractional anisotropy, trace of the diffusion tensor) as the outcomes and depressive symptoms as the predictor, while adjusting for age, sex, education, scanner, serotonin-reuptake inhibitor use, total volume of white-matter hyperintensities normalized by intracranial volume, and presence of white-matter hyperintensities at the voxel level.

Results

Higher level of self-reported late-life depressive symptoms was associated with greater diffusion-tensor trace (reduced white matter integrity) in connections between commissural pathways and contralateral prefrontal regions (superior and middle frontal/dorsolateral prefrontal cortex), association pathways connecting dorsolateral prefrontal cortex with insular, striatal and thalamic regions, and association pathways connecting the parietal, temporal and occipital lobes and the thalamus.

Discussion

This study demonstrated a discernable pattern of compromised white matter structural integrity underlying late-life depressive symptoms within older Black adults.

Stability and change in acculturation-related characteristics in older Latinos: Implications for culturally compatible ADRD research

Introduction

Acculturation-related characteristics, that is, factors directly connected to culture and familial relationships, are associated with engaged research participation within Latino communities. Despite this, little empirical data exists on whether acculturation changes over time in older Latinos, which has potential implications for Alzheimer's disease and related dementias (ADRD) research study design including longer duration clinical trial implementation.

Methods

Self-identified Latinos (n = 222; mean age = 71, 76% female) participating in one of three ongoing longitudinal community-based cohort studies of aging who reported their nativity outside of the United States/District of Columbia (US/DC) contributed, on average, 4.0 ± 1.2 years of annually collected data. This included acculturation-related characteristics of total, language-, and social-based scores from the Short Acculturation Scale for Hispanics (SASH) and total and domain-specific scores from an abbreviated Sabogal Familism questionnaire. We used ordinal mixed effects models and linear mixed effects models (as appropriate) to assess change in acculturation metrics after adjusting for age, sex, education, income, and duration of time in the US/DC.

Results

Although none of the SASH metrics changed over time (P-values ≥ 0.25), all Familism metrics declined over time (P-values ≤ 0.044). Additionally, select participant-based characteristics including years of education were significantly (and differentially) associated with level of, but not change in, acculturation-related outcomes.

Discussion

Results suggest that specific acculturation-related factors (i.e., familism) change over time in older Latinos, and participant-based characteristics associated with baseline levels of (but not change in) acculturation more generally. Thus, acculturation-related characteristics are not all static, trait-like qualities but rather a multi-faceted, and at times evolving, construct. Considering this dynamic phenotyping is important when contextualizing older Latinos' lived experience, and when designing, adapting, and conducting ADRD clinical trials and other health-related interventions.

A Longitudinal Study of Acculturation in Context and Cardiovascular Health and Their Effects on Cognition Among Older Latino Adults

Background We previously outlined the importance of considering acculturation within the context of older Latino adults' lived experience (ie, acculturation in context) to better capture contributors to cognitive aging. We now examine this conceptual framework as related to level of and change in cardiovascular health, and whether cardiovascular health modifies previously documented associations of acculturation in context with cognition. Methods and Results Acculturation in context data from 192 Latino participants without dementia at baseline (age ~70 years) were compiled into 3 separate composite scores: acculturation-related (nativity, language-, and social-based preferences), contextually related socioenvironmental (experiences of discrimination, social isolation, social networks), and familism-related (Latino-centric family ethos). A modified American Heart Association's Life's Simple 7 (mLS7; ie, smoking, physical activity, body mass index, blood pressure, total cholesterol, blood glucose) was used to measure cardiovascular health. Mixed effects regressions simultaneously tested the association of all 3 composite scores with total mLS7 adjusting for confounders. Separate models tested whether mLS7 modified associations of the 3 composite scores and cognition. The contextually related socioenvironmental composite score reflecting higher discrimination, higher social isolation, and smaller social networks (estimate=0.22, SE=0.10, P=0.02) and the familism score (estimate=0.16, SE=0.07, P=0.02) both significantly associated with change in total mLS7. The acculturation-related composite was not significantly associated with change in mLS7. No composite was significantly associated with level of mLS7. Total mLS7, however, significantly modified associations between the acculturation-related composite and change in working memory (estimate=-0.02, SE=0.01, P=0.043). Conclusions Acculturation within the context of older Latino adults' lived experience is important for maintaining cardiovascular health, relationships that also affect domain-specific cognitive decline.

Acculturation in Context and Brain Health in Older Latino Adults: A Diffusion Tensor Imaging Study

BACKGROUND

Latinos are at higher risk of developing mild cognitive impairment (MCI) and Alzheimer's disease than non-Latino Whites. Acculturation factors may influence this risk, yet there are few studies that have examined associations of acculturation, particularly in the context of socioenvironmental and familial factors, and brain health in older Latinos.

OBJECTIVE

To examine potential associations between acculturation in context and brain health in older Latinos.

METHODS

Using three previously established composites of acculturation-in-context, (acculturation-related: nativity status, language preference, acculturation scores; contextually-related socioenvironmental: perceived discrimination, loneliness/social isolation, social network size; and familism), and diffusion-tensor imaging (DTI), associations with white matter structural integrity were examined in 92 Latino adults without dementia participating in one of three epidemiological studies of aging. Linear regression models were used to test associations with DTI-derived metrics (fractional anisotropy, FA; trace) as separate outcomes and acculturation composite scores as individual predictors, while adjusting for age, sex, education, scanner, and white matter hyperintensities (voxelwise and total volumes normalized by intracranial volume).

RESULTS

Higher scores on the socioenvironmental composite were associated with lower FA in two clusters of left-hemisphere connections. Cluster 1 was dominated by both short association pathways connecting frontal regions and projection pathways connecting frontal regions with the thalamus. Cluster 2 was dominated by long association pathways connecting parietal, frontal, and temporal regions.

CONCLUSIONS

This study of older Latino adults demonstrated an association between reduced brain white matter integrity and contextually related socioenvironmental experiences known to increase risk of MCI and Alzheimer's disease.

Cognitive decline and hippocampal functional connectivity within older Black adults

While there has been a proliferation of neuroimaging studies on cognitive decline in older non-Hispanic White adults, there is a dearth of knowledge regarding neuroimaging correlates of cognitive decline in Black adults. Resting-state functional neuroimaging approaches may be particularly sensitive to early cognitive decline, but there are no studies that we know of that apply this approach to examining associations of brain function to cognition in older Black adults. We investigated the association of cognitive decline with whole-brain voxel-wise functional connectivity to the hippocampus, a key brain region functionally implicated in early Alzheimer's dementia, in 132 older Black adults without dementia participating in the Minority Aging Research Study and Rush Memory and Aging Project, two longitudinal studies of aging that include harmonized annual cognitive assessments and magnetic resonance imaging brain imaging. In models adjusted for demographic factors (age, education, sex), global cognitive decline was associated with functional connectivity of the hippocampus to three clusters in the right and left frontal regions of the dorsolateral prefrontal cortex. In domain-specific analyses, decline in semantic memory was associated with functional connectivity of the hippocampus to bilateral clusters in the precentral gyrus, and decline in perceptual speed was inversely associated with connectivity of the hippocampus to the bilateral intracalcarine cortex and the right fusiform gyrus. These findings elucidate neurobiological mechanisms underlying cognitive decline in older Black adults and may point to specific targets of intervention for Alzheimer's disease.

Acute versus chronic inflammatory markers and cognition in older black adults: Results from the Minority Aging Research Study

Peripheral inflammation is elevated in older Black adults, an elevation which prior work has suggested may be due to chronic stress associated with systemic racism and related adverse cardiovascular health conditions. Inflammation is also involved in the pathogenic processes of dementia; however, limited (and mixed) results exist concerning inflammation and cognitive decline in Black adults. We characterized patterns of inflammation and their role in cognitive decline in 280 older Black adults (age = 72.99 ± 6.00 years; 69.6% female) from the Minority Aging Research Study (MARS) who were without dementia at baseline and followed between 2 and 15 years (mean = 9 years). Participants completed a blood draw at baseline and annual cognitive evaluations. Serum was assayed for 9 peripheral inflammatory markers; 19 neuropsychological test scores were used to create indices of global cognition and five cognitive domains. Principal component analysis with varimax rotation characterized patterns of inflammation with factor loadings > 0.6 per component contributing to two composite scores representing acute/upstream and chronic/downstream inflammation. These composites were used as separate predictors in linear mixed regression models to determine associations with level and change in cognition adjusting for relevant covariates. Higher baseline upstream/acute inflammation associated with lower baseline semantic memory (p = .040) and perceptual speed (p = .046); it was not related to cognitive decline. By contrast, higher baseline downstream/chronic inflammation associated with faster declines in global cognition (p = .010), episodic (p = .027) and working memory (p = .006); it was not related to baseline cognition. For older Black adults, chronic, but not acute, inflammation may be a risk factor for changes in cognition.

Relationship of Blood Pressure and White Matter Hyperintensity Burden With Level of and Change in Cognition in Older Black Adults

OBJECTIVE

Elevations in blood pressure (BP) and associated white matter hyperintensities (WMHs) are chronic comorbid conditions among older Black adults. We investigated whether WMHs modify the association between late-life BP and cognition within older Black adults.

METHODS

A total of 167 Black adults (age, ~75 years; without dementia at baseline) participating in neuroimaging studies at the Rush Alzheimer's Disease Center were evaluated for BP markers of cardiovascular health, including systolic BP, diastolic BP, pulse pressure, mean arterial pressure (MAP), and hypertension, and were assessed for global and domain-specific cognition at baseline and annually for up to 8 years. WMHs adjusted for intracranial volume were quantified at baseline.

RESULTS

Models adjusted for relevant confounders and the interaction of these variables with time revealed differential associations between BP markers and baseline cognition; however, only elevated diastolic BP predicted faster cognitive, that is, episodic memory, decline (estimate = -0.002, standard error = 0.0009, p = .002). Although WMH burden did not modify the association between diastolic BP and episodic memory decline, it did interact with diastolic BP to lower episodic memory at baseline (estimate = -0.051, standard error = 0.012, p = .0001); that is, greater WMHs combined with higher diastolic BP resulted in the lowest baseline episodic memory scores. A similar profile was noted for WMHs, MAP, and baseline episodic memory. Hypertension was neither associated with cognition nor modified by WMH burden after multiple comparisons correction.

CONCLUSION

Late-life diastolic BP was associated with faster rates of episodic memory decline in older Black adults; together with higher WMH burden, it (and MAP) lowered the point at which individuals begin their course of decline toward pathological aging.

Associations of deformation-based brain morphometry with cognitive level and decline within older Blacks without dementia

Blacks are at higher risk of developing cognitive impairment with age than non-Hispanic Whites, yet most brain morphometry and cognition research is performed with White samples or with mixed samples that control for race or compare across racial groups. A deeper understanding of the within-group variability in associations between brain structure and cognitive decline in Blacks is critically important for designing appropriate outcomes for clinical trials, predicting adverse outcomes, and developing interventions to preserve cognitive function, but no studies have examined these associations longitudinally within Blacks. We performed deformation-based morphometry in 376 older Black participants without dementia and examined associations of deformation-based morphometry with cognitive level and decline for global cognition and five cognitive domains. After correcting for widespread age-associated effects, there remained regions with less tissue and more cerebrospinal fluid associated with level and rate of decline in global cognition, memory, and perceptual speed. Further study is needed to examine the moderators of these associations, identify adverse outcomes predicted by brain morphometry, and deepen knowledge of underlying biological mechanisms.

Leveraging virtual reality to train certified nursing assistants as essential dementia-care personnel in the age of COVID-19

Background

COVID‐19 has placed an extraordinary and disproportionate level of responsibility and risk on certified nursing assistants (CNAs) caring for persons with dementia (PWD) relative to their training, resources, and compensation levels. Nearly one‐quarter of COVID‐19 deaths in the United States have been nursing home residents and staff. Despite providing the majority of direct care, CNAs are amongst the most under‐resourced and under‐trained frontline workers. Given their essentiality, it is critical to support CNAs during the COVID‐19 pandemic. The purpose of this work is to provide CNAs with a space to strengthen their knowledge and confidence in caring for PWD. This pilot study applies a virtual reality (VR) curriculum to train CNAs regarding the lived experiences of PWD and their loved ones. The VR vignette portrays a Latinx woman, Beatriz, through progressive stages of Alzheimer’s disease.

Method

Chicago Methodist Senior Services (CMSS) CNAs were recruited (N=7; 86% female, 86% Black) for a seven‐week online training program consisting of 1.5 hours per week. Each class included a didactic lecture and an Embodied Labs VR module depicting a first‐person experience of dementia through a distributive model approach. The program concluded with two recorded focus groups. Participants completed the UCLA Geriatric Attitudes Scale, a dementia knowledge assessment, the Interpersonal Reactivity Index surveys, and a COVID‐19 Impact questionnaire. Current analyses include qualitative content analysis for focus group data and descriptive, quantitative statistics for pre‐and post‐VR intervention surveys.

Result

Preliminary results demonstrate that CNAs endorsed a positive change in attitudes toward older adults (p=0.069), a deepened understanding of dementia, and increased confidence in caregiving skills. Focus groups allowed CNAs to discuss changes in resident behavior and support one another through a virtual platform during a global pandemic.

Conclusion

Combining traditional didactic lectures with VR‐based curricula provided CNAs with foundational knowledge and first‐hand experience of dementia pathology. Participants reported greater levels of insight and empathy for PWD. Future aims include expansion of training content to include end‐of‐life conversations, LGBTQIA aging, and Lewy body dementia.

Bootstrap approach for meta-synthesis of MRI findings from multiple scanners

BACKGROUND

Neuroimaging data from large epidemiologic cohort studies often come from multiple scanners. The variations of MRI measurements due to differences in magnetic field strength, image acquisition protocols, and scanner vendors can influence the interpretation of aggregated data. The purpose of the present study was to compare methods that meta-analyze findings from a small number of different MRI scanners.

METHODS

We proposed a bootstrap resampling method using individual participant data and compared it with two common random effects meta-analysis methods, DerSimonian-Laird and Hartung-Knapp, and a conventional pooling method that combines MRI data from different scanners. We first performed simulations to compare the power and coverage probabilities of the four methods in the absence and presence of scanner effects on measurements. We then examined the association of age with white matter hyperintensity (WMH) volumes from 787 participants.

RESULTS

In simulations, the bootstrap approach performed better than the other three methods in terms of coverage probability and power when scanner differences were present. However, the bootstrap approach was consistent with pooling, the optimal approach, when scanner differences were absent. In the association of age with WMH volume, we observed that age was significantly associated with WMH volumes using the bootstrap approach, pooling, and the DerSimonian-Laird method, but not using the Hartung-Knapp method (p < 0.0001 for the bootstrap approach, DerSimonian-Laird, and pooling but p = 0.1439 for the Hartung-Knapp approach).

CONCLUSION

The bootstrap approach using individual participant data is suitable for integrating outcomes from multiple MRI scanners regardless of absence or presence of scanner effects on measurements.

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.

Antiphospholipid Antibodies: Cognitive and Motor Decline, Neuroimaging and Neuropathology

BACKGROUND

Few data are available on associations of antiphospholipid (aPL) antibodies with cognitive and motor decline in aging, and cerebrovascular disease on in vivo neuroimaging and postmortem neuropathology.

METHODS

This longitudinal, clinical-pathologic study (aPL antibodies, brain infarcts, and cognitive and motor decline in aging), was derived from 2 ongoing community-based cohort studies. A panel of 3 aPL antibodies was assayed in serum from 956 older individuals (mean age = 81.1 years; 72% women). Serum was also tested in a subset for markers of inflammation (C-reactive protein [CRP]) and blood-brain barrier breakdown (matrix metalloproteinases, MMPs). Annual clinical evaluations documented cognitive (17 neuropsychological tests) and motor function including parkinsonism. Cerebrovascular disease data were derived from in vivo neuroimaging and postmortem neuropathologic evaluations (699 individuals). We examined associations of aPL with cognitive and motor decline, other serum markers, neuroimaging, and neuropathology.

RESULTS

Of 956 individuals, 197 (20.6%) had aPL positivity, defined as positivity on any of the assays, at the time of first measurement. During a mean follow-up of 6.6 years (SD 4), overall aPL positivity was not associated with change in global cognition (estimate = -0.005, SE 0.011; p = 0.622) or parkinsonian signs (estimate = -0.003, SE 0.017; p = 0.860). aPL were not associated with serum CRP or MMPs (both p > 0.268). aPL were not associated with in vivo brain magnetic resonance imaging white matter hyperintensities or infarcts (both p > 0.376). Among those autopsied, aPL were not associated with pathologically confirmed brain infarcts, or cerebral atherosclerosis or arteriolosclerosis (all p≥ 0.447).

CONCLUSIONS

In older individuals followed longitudinally, aPL do not relate to cognitive or motor decline, inflammation, or cerebrovascular disease on in vivo neuroimaging or postmortem neuropathology.

Neopterin is associated with hippocampal subfield volumes and cognition in HIV

Objective

HIV infection sets off an immediate immune response and inflammatory cascade that can lead to neuronal injury and cognitive impairment, but the relationship between immune markers, regional brain volumes, and cognition remains understudied in HIV-infected adults.

Methods

Cross-sectional associations were examined between serum immune markers of activation (neopterin) and inflammation (interleukin [IL]-1β, IL-6, tumor necrosis factor alpha, and C-reactive protein) with regional brain volumes (cortical, subcortical, total gray matter, hippocampus, and subfields) and cognition in 66 HIV-infected, virally suppressed, adults who underwent 3.0-T MRI as part of the Research Core of the Rush Center of Excellence on Disparities in HIV and Aging. Immune markers were assayed from frozen plasma, values were entered into linear regression models as predictors of regional brain volumes, and interactive effects of immune response and regional brain volumes on cognition were examined.

Results

No inflammatory marker was associated with any regional brain volume. Higher neopterin level was associated with lower total hippocampal, presubiculum, and cornu ammonis (CA) subfield volumes. Higher neopterin level and lower total hippocampal volume were independently associated with lower episodic memory, and neopterin level fully mediated the effect of hippocampal atrophy on episodic memory. Higher neopterin levels were associated with lower presubiculum, CA1, and CA4/dentate volumes and lower semantic memory, working memory, and global cognition.

Conclusion

Immune activation in response to HIV infection, measured by neopterin, has a deleterious and targeted effect on regional brain structure, which can be visualized with clinically available MRI measures of hippocampus and its subfields, and this effect is associated with lower cognitive function.

Memory complaints, dementia, and neuropathology in older blacks and whites

OBJECTIVE

To determine relationships of memory complaints to cognitive function and decline, incident dementia, and neurodegenerative and other neuropathologies, as well as the population-attributable risk for dementia in older black and white persons.

METHODS

A total of 4,015 community-based persons (28% black; 74% women; mean baseline age = 78 years) were enrolled in 1 of 4 longitudinal cohort studies, and another 2,937 in a population-based cohort. Memory scores, assessed using 2 questions (5-point Likert scales) were categorized as complaints present or absent. Global cognition and 5 cognitive domains were derived from annual neuropsychological tests. Dementia was assessed from these tests and additional data. Neuropathologic data were available for 1,350 deceased subjects with brain autopsies. Regression and mixed effects models were used to examine relationships of memory complaints to cognition and neuropathology.

RESULTS

Baseline memory complaints (n = 1,310; 33% of 4,015) were associated with lower cognition and faster decline in all domains (global score estimate = -0.032, standard error = 0.004, p < 0.0001), during a mean follow-up of 6 (standard deviation = 2) years. Persons with memory complaints had higher dementia risk (hazard ratio = 1.64, 95% confidence interval [CI] = 1.42-1.89) and odds of pathologic Alzheimer disease (odds ratio [OR] = 1.96, 95% CI = 1.51-2.54), neocortical Lewy bodies (OR = 2.47, 95% CI = 1.54-3.96), and other neurodegenerative pathologies. Results for dementia risk were similar among blacks and whites. Among 2,937 older persons in a population-based cohort with similar data, the population-attributable risk for incident dementia due to memory complaints was 14.0% (95% CI = 2.6-23.0), and did not vary between the black and white groups.

INTERPRETATION

Memory complaints are common in older black and white persons, and relate to cognitive decline, dementia risk, and neurodegenerative pathologies. Ann Neurol 2018;83:718-729.

Grey matter correlates of susceptibility to scams in community-dwelling older adults

Susceptibility to scams is a significant issue among older adults, even among those with intact cognition. Age-related changes in brain macrostructure may be associated with susceptibility to scams; however, this has yet to be explored. Based on previous work implicating frontal and temporal lobe functioning as important in decision making, we tested the hypothesis that susceptibility to scams is associated with smaller grey matter volume in frontal and temporal lobe regions in a large community-dwelling cohort of non-demented older adults. Participants (N = 327, mean age = 81.55, mean education = 15.30, 78.9 % female) completed a self-report measure used to assess susceptibility to scams and an MRI brain scan. Results indicated an inverse association between overall grey matter and susceptibility to scams in models adjusted for age, education, and sex; and in models further adjusted for cognitive function. No significant associations were observed for white matter, cerebrospinal fluid, or total brain volume. Models adjusted for age, education, and sex revealed seven clusters showing smaller grey matter in the right parahippocampal/hippocampal/fusiform, left middle temporal, left orbitofrontal, right ventromedial prefrontal, right middle temporal, right precuneus, and right dorsolateral prefrontal regions. In models further adjusted for cognitive function, results revealed three significant clusters showing smaller grey matter in the right parahippocampal/hippocampal/fusiform, right hippocampal, and right middle temporal regions. Lower grey matter concentration in specific brain regions may be associated with susceptibility to scams, even after adjusting for cognitive ability. Future research is needed to determine whether grey matter reductions in these regions may be a biomarker for susceptibility to scams in old age.

Entorhinal Cortex: Antemortem Cortical Thickness and Postmortem Neurofibrillary Tangles and Amyloid Pathology

BACKGROUND AND PURPOSE

The entorhinal cortex, a critical gateway between the neocortex and hippocampus, is one of the earliest regions affected by Alzheimer disease-associated neurofibrillary tangle pathology. Although our prior work has automatically delineated an MR imaging-based measure of the entorhinal cortex, whether antemortem entorhinal cortex thickness is associated with postmortem tangle burden within the entorhinal cortex is still unknown. Our objective was to evaluate the relationship between antemortem MRI measures of entorhinal cortex thickness and postmortem neuropathological measures.

MATERIALS AND METHODS

We evaluated 50 participants from the Rush Memory and Aging Project with antemortem structural T1-weighted MR imaging and postmortem neuropathologic assessments. Here, we focused on thickness within the entorhinal cortex as anatomically defined by our previously developed MR imaging parcellation system (Desikan-Killiany Atlas in FreeSurfer). Using linear regression, we evaluated the association between entorhinal cortex thickness and tangles and amyloid-β load within the entorhinal cortex and medial temporal and neocortical regions.

RESULTS

We found a significant relationship between antemortem entorhinal cortex thickness and entorhinal cortex (P = .006) and medial temporal lobe tangles (P = .002); we found no relationship between entorhinal cortex thickness and entorhinal cortex (P = .09) and medial temporal lobe amyloid-β (P = .09). We also found a significant association between entorhinal cortex thickness and cortical tangles (P = .003) and amyloid-β (P = .01). We found no relationship between parahippocampal gyrus thickness and entorhinal cortex (P = .31) and medial temporal lobe tangles (P = .051).

CONCLUSIONS

Our findings indicate that entorhinal cortex-associated in vivo cortical thinning may represent a marker of postmortem medial temporal and neocortical Alzheimer disease pathology.

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg=-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness.

Novel genetic loci underlying human intracranial volume identified through genome-wide association

Intracranial volume reflects the maximally attained brain size during development, and remains stable with loss of tissue in late life. It is highly heritable, but the underlying genes remain largely undetermined. In a genome-wide association study of 32,438 adults, we discovered five previously unknown loci for intracranial volume and confirmed two known signals. Four of the loci were also associated with adult human stature, but these remained associated with intracranial volume after adjusting for height. We found a high genetic correlation with child head circumference (ρgenetic = 0.748), which indicates a similar genetic background and allowed us to identify four additional loci through meta-analysis (Ncombined = 37,345). Variants for intracranial volume were also related to childhood and adult cognitive function, and Parkinson's disease, and were enriched near genes involved in growth pathways, including PI3K-AKT signaling. These findings identify the biological underpinnings of intracranial volume and their link to physiological and pathological traits.

White matter hyperintensities, incident mild cognitive impairment, and cognitive decline in old age

Objective

Examine the association of white matter hyperintensities (WMH) with risk of incident mild cognitive impairment (MCI) and rate of decline in multiple cognitive systems in community‐based older persons.

Methods

Participants (n = 354) were older persons initially free of cognitive impairment from two ongoing longitudinal epidemiologic studies of aging. All underwent brain magnetic resonance imaging (MRI) for quantification of WMH and gray matter volumes and detailed annual clinical evaluations including 17 cognitive tests. Proportional hazards models were used to examine the relationship between WMH and incident MCI, and mixed‐effects models were used to examine the relationship between WMH and decline in global cognition and five specific cognitive systems.

Results

During up to about 6 years of follow‐up (mean = 4.1), 106 (30% of 354) persons developed MCI. In a proportional hazards model adjusted for age, gender, and education, WMH volume was associated with a substantially increased risk of MCI (P < 0.001). Thus, a person with a high WMH volume (90th percentile) was about 2.7 times more likely to develop MCI compared to a person with a low volume (10th percentile). WMH volume also was associated with an increased rate of decline in global cognition (P < 0.001), perceptual speed, working memory, episodic memory, and semantic memory. Associations persisted after adjustment for total gray matter volume, vascular risk factors, and vascular diseases.

Interpretation

WMH contribute to the development of MCI and are associated with progressive decline in multiple cognitive systems in old age.

Double Dissociation Between Memory Systems Underlying Explicit and Implicit Memory in the Human Brain

Amnesic patients have impaired explicit memory that is evident in poor recall and recognition of words, yet can have intact implicit memory for words as measured by repetition priming, the enhanced efficiency for reprocessing those words The dissociation between explicit and implicit memory for words is a fundamental characteristic of normal cognition that could reflect two different functional architectures of the human brain two separate processing systems or two levels of operation of a single system with implicit memory less demanding of that system We present a patient who has a lesion in the right occipital lobe and who showed intact explicit and impaired implicit memory for words The deficit was specific to visual priming The double dissociation between explicit and implicit visual memory for words indicates that separate processing systems mediate these two forms of memory, and that a memory system in right occipital cortex mediates implicit visual memory for words

Cerebrovascular and microglial states are not altered by functional neuroinflammatory gene variant

The translocator protein, a microglial-expressed marker of neuroinflammation, has been implicated in Alzheimer's disease, which is characterized by alterations in vascular and inflammatory states. ATSPOvariant, rs6971, determines binding affinity of exogenous radioligandsin vivo; however, the effect of these altered binding characteristics on inflammatory and cerebrovascular biomarkers has not been assessed. In 2345 living subjects (Alzheimer's Disease Neuroimaging Initiative, n = 1330) and postmortem brain samples (Religious Orders Study and Memory and Aging Project, n = 1015), we analyzed effects of rs6971 on white matter hyperintensisites, cerebral infarcts, circulating inflammatory biomarkers, amyloid angiopathy, and microglial activation. We found that rs6971 does not alter translocator protein in a way that impacts cerebrovascular and inflammatory states known to be affected in dementia.

Regional Neocortical Gray Matter Structure and Sleep Fragmentation in Older Adults

STUDY OBJECTIVES

To test the hypothesis that greater sleep fragmentation is associated with regionally decreased cortical gray matter volume in older community-dwelling adults without cognitive impairment.

METHODS

We studied 141 community-dwelling older adults (median age 82.9; 73% female) without cognitive impairment or stroke, and not using sedative/ hypnotic medications, participating in the Rush Memory and Aging Project. We quantified sleep fragmentation from 7 d of actigraphy using the metric kRA and related this to total cortical gray matter volume, and regional gray matter volume in 34 cortical regions quantified by automated segmentation of magnetic resonance imaging data. We determined statistical significance and accounted for multiple comparisons by empirically estimating the false discovery rate by permutation.

RESULTS

Lower total cortical gray matter volume was associated with higher sleep fragmentation (coefficient +0.23, standard error [SE] 0.11, P = 0.037). Lower gray matter volumes in four cortical regions were accompanied by higher sleep fragmentation with a false discovery rate < 0.05: the left (coefficient +0.36, SE 0.10, P = 2.7 × 10(-4)) and right (coefficient +0.31, SE 0.10, P = 4.0 × 10(-3)) lateral orbitofrontal cortices, and the adjacent left (coefficient +0.31, SE 0.10, 5.4 × 10(-4)) and right (coefficient +0.39, SE 0.10, P = 1.2 × 10(-4)) inferior frontal gyri pars orbitalis. These associations were unchanged after accounting for age, sex, education, depression, cognitive function, and a number of medical comorbidities.

CONCLUSIONS

Lower cortical gray matter volume in the lateral orbitofrontal cortex and inferior frontal gyrus pars orbitalis is associated with greater sleep fragmentation in older community-dwelling adults. Further work is needed to clarify whether this is a consequence of or contributor to sleep fragmentation.

COMMENTARY

A commentary on this article appears in this issue on page 15.

Association of white matter hyperintensities and gray matter volume with cognition in older individuals without cognitive impairment

Both presence of white matter hyperintensities (WMH) and smaller total gray matter volume on brain magnetic resonance imaging (MRI) are common findings in old age, and contribute to impaired cognition. We tested whether total WMH volume and gray matter volume had independent associations with cognition in community-dwelling individuals without dementia or mild cognitive impairment (MCI). We used data from participants of the Rush Memory and Aging Project. Brain MRI was available in 209 subjects without dementia or MCI (mean age 80; education = 15 years; 74 % women). WMH and gray matter were automatically segmented, and the total WMH and gray matter volumes were measured. Both MRI-derived measures were normalized by the intracranial volume. Cognitive data included composite measures of five different cognitive domains, based on 19 individual tests. Linear regression analyses, adjusted for age, sex, and education, were used to examine the relationship of logarithmically-transformed total WMH volume and of total gray matter volume to cognition. Larger total WMH volumes were associated with lower levels of perceptual speed (p < 0.001), but not with episodic memory, semantic memory, working memory, or visuospatial abilities (all p > 0.10). Smaller total gray matter volumes were associated with lower levels of perceptual speed (p = 0.013) and episodic memory (p = 0.001), but not with the other three cognitive domains (all p > 0.14). Larger total WMH volume was correlated with smaller total gray matter volume (p < 0.001). In a model with both MRI-derived measures included, the relation of WMH to perceptual speed remained significant (p < 0.001), while gray matter volumes were no longer related (p = 0.14). This study of older community-dwelling individuals without overt cognitive impairment suggests that the association of larger total WMH volume with lower perceptual speed is independent of total gray matter volume. These results help elucidate the pathological processes leading to lower cognitive function in aging.

Physical activity, motor function, and white matter hyperintensity burden in healthy older adults

OBJECTIVE

To test the hypothesis that physical activity modifies the association between white matter hyperintensity (WMH) burden and motor function in healthy older persons without dementia.

METHODS

Total daily activity (exercise and nonexercise physical activity) was measured for up to 11 days with actigraphy (Actical; Philips Respironics, Bend, OR) in 167 older adults without dementia participating in the Rush Memory and Aging Project. Eleven motor performances were summarized into a previously described global motor score. WMH volume was expressed as percent of intracranial volume. Linear regression models, adjusted for age, education, and sex, were performed with total WMH volume as the predictor and global motor score as the outcome. Terms for total daily physical activity and its interaction with WMH volume were then added to the model.

RESULTS

Higher WMH burden was associated with lower motor function (p = 0.006), and total daily activity was positively associated with motor function (p = 0.002). Total daily activity modified the association between WMH and motor function (p = 0.007). WMH burden was not associated with motor function in persons with high activity (90th percentile). By contrast, higher WMH burden remained associated with lower motor function in persons with average (50th percentile; estimate = -0.304, slope = -0.133) and low (10th percentile; estimate = -1.793, slope = -0.241) activity.

CONCLUSIONS

Higher levels of physical activity may reduce the effect of WMH burden on motor function in healthy older adults.

An evaluation of MSDC-0160, a prototype mTOT modulating insulin sensitizer, in patients with mild Alzheimer's disease

Alzheimer’s disease (AD) is associated with insulin resistance and specific regional declines in cerebral metabolism. The effects of a novel mTOT modulating insulin sensitizer (MSDC-0160) were explored in non-diabetic patients with mild AD to determine whether treatment would impact glucose metabolism measured by FDG-PET in regions that decline in AD. MSDC-0160 (150 mg once daily; N=16) compared to placebo (N=13) for 12 weeks did not result in a significant difference in glucose metabolism in pre-defined regions when referenced to the pons or whole brain. However, glucose metabolism referenced to cerebellum was maintained in MSDC-0160 treated participants while it significantly declined for placebo patients in anterior and posterior cingulate, and parietal, lateral temporal, medial temporal cortices. Voxel-based analyses showed additional differences in FDG-PET related to MSDC-0160 treatment. These exploratory results suggest central effects of MSDC-0160 and provide a basis for further investigation of mTOT modulating insulin sensitizers in AD patients.

Financial literacy is associated with medial brain region functional connectivity in old age

Financial literacy refers to the ability to access and utilize financial information in ways that promote better outcomes. In old age, financial literacy has been associated with a wide range of positive characteristics; however, the neural correlates remain unclear. Recent work has suggested greater co-activity between anterior-posterior medial brain regions is associated with better brain functioning. We hypothesized financial literacy would be associated with this pattern. We assessed whole-brain functional connectivity to a posterior cingulate cortex (PCC) seed region of interest (ROI) in 138 participants of the Rush Memory and Aging Project. Results revealed financial literacy was associated with greater functional connectivity between the PCC and three regions: the right ventromedial prefrontal cortex (vmPFC), the left postcentral gyrus, and the right precuneus. Results also revealed financial literacy was associated negatively with functional connectivity between the PCC and left caudate. Post hoc analyses showed the PCC-vmPFC relationship accounted for the most variance in a regression model adjusted for all four significant functional connectivity relationships, demographic factors, and global cognition. These findings provide information on the neural mechanisms associated with financial literacy in old age.

Ventromedial PFC, parahippocampal, and cerebellar connectivity are associated with temporal discounting in old age

Temporal discounting occurs when a greater delayed reward is forsaken for a smaller immediate reward, and has been associated with a number of financial and health care outcomes important for older adults. Using resting-state fMRI and seed regions of interest in the left and right fronto-insular (FI) cortices, we explored the neurobiological substrate of temporal discounting in 123 non-demented older adults from the Rush Memory and Aging Project. For the left FI cortex, temporal discounting was positively associated with functional connectivity to the right ventromedial prefrontal cortex and middle temporal regions, and negatively associated with parahippocampal and right cerebellar regions. For the right FI cortex, temporal discounting was negatively associated with functional connectivity to a right cerebellar region. Connectivity maps of both left and right seed regions of interest overlapped in the right cerebellum. Results support the notion of different brain functional connectivity patterns associated with the dynamic range of temporal discounting in old age.

Systemic inflammation in non-demented elderly human subjects: brain microstructure and cognition

The purpose of this study was to test the hypothesis that higher levels of systemic inflammation in a community sample of non-demented subjects older than seventy years of age are associated with reduced diffusion anisotropy in brain white matter and lower cognition. Ninety-five older persons without dementia underwent detailed clinical and cognitive evaluation and magnetic resonance imaging, including diffusion tensor imaging. Systemic inflammation was assessed with a composite measure of commonly used circulating inflammatory markers (C-reactive protein and tumor necrosis factor-alpha). Tract-based spatial statistics analyses demonstrated that diffusion anisotropy in the body and isthmus of the corpus callosum was negatively correlated with the composite measure of systemic inflammation, controlling for demographic, clinical and radiologic factors. Visuospatial ability was negatively correlated with systemic inflammation, and diffusion anisotropy in the body and isthmus of the corpus callosum was shown to mediate this association. The findings of the present study suggest that higher levels of systemic inflammation may be associated with lower microstructural integrity in the corpus callosum of non-demented elderly individuals, and this may partially explain the finding of reduced higher-order visual cognition in aging.

Gray-matter macrostructure in cognitively healthy older persons: associations with age and cognition

A deeper understanding of brain macrostructure and its associations with cognition in persons who are considered cognitively healthy is critical to the early detection of persons at risk of developing dementia. Few studies have examined the associations of all three gray-matter macrostructural brain indices (volume, thickness, surface area) with age and cognition, in the same persons who are over the age of 65 and do not have cognitive impairment. We performed automated morphometric reconstruction of total gray matter, cortical gray matter, subcortical gray matter and 84 individual regions in 186 persons (60 % over the age of 80) without cognitive impairment. Morphometric measures were scaled and expressed as difference per decade of age and an adjusted score was created to identify those regions in which there was greater atrophy per decade of age compared to cortical or subcortical brain averages. The results showed that there is substantial total volume loss and cortical thinning in cognitively healthy older persons. Thinning was more widespread than volume loss, but volume loss, particularly in temporoparietal and hippocampal regions, was more strongly associated with cognition.

Functional connectivity networks associated with chronic musculoskeletal pain in old age

OBJECTIVE

Musculoskeletal disorders are common and often lead to chronic pain in older adults. Because the efficacy of interventions varies with the duration of pain, the identification of early biomarkers for chronic pain would have important public health consequences. Imaging of functional connectivity differences between brain regions might identify some of the earliest functional consequences of a disease process. We tested the hypothesis that chronic musculoskeletal pain in older persons is associated with changes in functional brain connectivity.

METHOD

We used resting-state functional magnetic resonance imaging and a spherical seed-based region of interest approach to assess functional connectivity of brain regions on a sample of 128 (64 who reported chronic musculoskeletal pain and 64 demographically matched, pain free) nondemented older adults from the Memory and Aging Project, a clinical-pathological cohort study of aging and dementia.

RESULTS

Older adults with chronic pain showed greater functional connectivity between the posterior cingulate and left insula, left superior temporal gyrus, and left cerebellum.

CONCLUSION

Chronic musculoskeletal pain is associated with a specific pattern of functional connectivity between brain regions among older adults.

Faster cognitive decline in the years prior to MR imaging is associated with smaller hippocampal volumes in cognitively healthy older persons

Early identification of persons at risk for cognitive decline in aging is critical to optimizing treatment to delay or avoid a clinical diagnosis of mild cognitive impairment (MCI) or dementia due to Alzheimer's disease (AD). To accomplish early identification, it is essential that trajectories of cognitive change be characterized and associations with established biomarkers of MCI and AD be examined during the phase in which older persons are considered cognitively healthy. Here we examined the association of rate of cognitive decline in the years leading up to structural magnetic resonance imaging with an established biomarker, hippocampal volume. The sample comprised 211 participants of the Rush Memory and Aging Project who had an average of 5.5 years of cognitive data prior to structural scanning. Results showed that there was significant variability in the trajectories of cognitive change prior to imaging and that faster cognitive decline was associated with smaller hippocampal volumes. Domain-specific analyses suggested that this association was primarily driven by decline in working memory. The results emphasize the importance of closely examining cognitive change and its association with brain structure during the years in which older persons are considered cognitively healthy.

Antiphospholipid antibodies, brain infarcts, and cognitive and motor decline in aging (ABICMA): design of a community-based, longitudinal, clinical-pathological study

The overall goal of the Antiphospholipid Antibodies, Brain Infarcts, and Cognitive and Motor Decline in Aging study is to test the hypothesis that antiphospholipid antibodies (aPL) are associated with an increased risk of pathologically proven brain infarcts and are related to cognitive and motor decline in aging. Putative biologic mechanisms underlying the association of aPL with infarcts and the relation of aPL with clinical outcomes of cognitive and motor impairment, including vascular and other processes, will be examined. The design of this longitudinal, clinical-pathologic study involves quantifying four aPL assays, and relating these to brain infarcts, and to cognitive and motor decline. Vascular mechanisms assessed using antemortem magnetic resonance neuroimaging and postmortem neuropathology, as well as nonvascular mechanisms of inflammation and blood-brain barrier permeability alterations will be examined as plausible mediators of the relation of aPL to cognitive and motor impairment. We will take advantage of antemortem biological specimens (longitudinally collected sera and plasma from which aPL, annexins, C-reactive protein, and matrix metalloproteinases will be quantified), and clinical, neuroimaging, and postmortem neuropathologic data from about 800 elderly, community-dwelling women and men who have agreed to brain autopsy at the time of death, participating in one of two ongoing studies of aging: the Religious Orders Study and the Memory and Aging Project.

Neural intrinsic connectivity networks associated with risk aversion in old age

Risk aversion is associated with several important real world outcomes. Although the neurobiological correlates of risk aversion have been studied in young persons, little is known of the neurobiological correlates of risk aversion among older persons. Resting-state functional MRI data were collected on 134 non-demented participants of the Rush Memory and Aging Project, a community-based cohort study of aging. Risk aversion was measured using a series of standard questions in which participants were asked to choose between a certain monetary payment ($15) versus a gamble in which they could gain more than $15 or gain nothing, with potential gains varied across questions. Participants determined to be "high" (n=27) and "low" (n=27) in risk aversion were grouped accordingly. Using a spherical seed region of interest in the anterior cingulate cortex, voxel-wise functional connectivity network similarities were observed in bilateral frontal, anterior and posterior cingulate, insula, basal ganglia, temporal, parietal, and thalamic regions. Differences in functional connectivity were observed such that those low in risk aversion had greater connectivity to clusters in the superior, middle, and medial frontal regions, as well as cerebellar, parietal, occipital, and inferior temporal regions. Those high in risk aversion had greater connectivity to clusters in the inferior and orbital frontal, parahippocampal, and insula regions, as well as thalamic, parietal, precentral gyrus, postcentral gyrus, and middle temporal regions. Similarities and differences in functional connectivity patterns may reflect the historical recruitment of specific brain regions as a network in the active processing of risk in older adults.

Association between late-life social activity and motor decline in older adults

BACKGROUND

Loss of motor function is a common consequence of aging, but little is known about the factors that predict idiopathic motor decline. Our objective was to test the hypothesis that late-life social activity is related to the rate of change in motor function in old age.

METHODS

Longitudinal cohort study with a mean follow-up of 4.9 years with 906 persons without stroke, Parkinson disease, or dementia participating in the Rush Memory and Aging Project. At baseline, participants rated the frequency of their current participation in common social activities from which a summary measure of social activity was derived. The main outcome measure was annual change in a composite measure of global motor function, based on 9 measures of muscle strength and 9 motor performances.

RESULTS

Mean (SD) social activity score at baseline was 2.6 (0.58), with higher scores indicating more frequent participation in social activities. In a generalized estimating equation model, controlling for age, sex, and education, global motor function declined by approximately 0.05 U/y (estimate, 0.016; 95% confidence interval [CI], -0.057 to 0.041 [P = .02]). Each 1-point decrease in social activity was associated with approximately a 33% more rapid rate of decline in motor function (estimate, 0.016; 95% CI, 0.003 to 0.029 [P = .02]). The effect of each 1-point decrease in the social activity score at baseline on the rate of change in global motor function was the same as being approximately 5 years older at baseline (age estimate, -0.003; 95% CI, -0.004 to -0.002 [P<.001]). Furthermore, this amount of motor decline per year was associated with a more than 40% increased risk of death (hazard ratio, 1.44; 95% CI, 1.30 to 1.60) and a 65% increased risk of incident Katz disability (hazard ratio, 1.65; 95% CI, 1.48 to 1.83). The association of social activity with the rate of global motor decline did not vary along demographic lines and was unchanged (estimate, 0.025; 95% CI, 0.005 to 0.045 [P = .01]) after controlling for potential confounders including late-life physical and cognitive activity, disability, global cognition depressive symptoms, body composition, and chronic medical conditions.

CONCLUSION

Less frequent participation in social activities is associated with a more rapid rate of motor function decline in old age.

Repetition priming and change in functional ability in older persons without dementia

Adverse consequences such as institutionalization and death are associated with compromised activities of daily living in aging, yet there is little known about risk factors for the development and progression of functional disability. Using generalized linear models, the authors examined the association between the ability to benefit from repetition and rate of change in functional ability in 160 nondemented elders participating in the Religious Orders Study. Three single-word repetition priming tasks were administered that varied in the degree to which visual-perceptual or conceptual processing was invoked. Decline in functional ability was less rapid, during follow-up of up to 10 years, in persons with better baseline priming performance on a task known to draw on both visual-perceptual and conceptual processing (word-stem completion). By contrast, change in functional ability was not associated with priming on tasks that are known to draw primarily on either visual-perceptual (threshold word-identification) or conceptual (category exemplar production) processing. The results are discussed in terms of a common biological substrate in the inferotemporal neocortex, supporting efficient processing of meaningful visual-perceptual experience and proficient performance of activities of daily living.

Visuoperceptual repetition priming and progression of parkinsonian signs in aging

Parkinsonian signs in older persons are associated with numerous adverse health outcomes, however there is limited information about factors which predict progression of these signs. Using generalized linear models, we examined the association between efficiency in visuoperceptual and conceptual processing, measured by repetition priming, and rate of change in parkinsonian signs in a large sample of older persons without cognitive impairment or Parkinson's disease. Subjects with better visuoperceptual priming, measured by threshold word-identification and word-stem completion, at study baseline, progressed more slowly during follow-up of up to 11 years. Conceptual priming was not associated with change in parkinsonian signs. The findings demonstrate that individual differences in visuoperceptual processing efficiency, measured by repetition priming, occur in older persons without cognitive impairment and predict important changes in motor function. Reduced visuoperceptual priming in aging may be an early signal of vulnerability in a corticostrial circuit that contributes to sensorimotor integration.

Repetition priming in aging and Alzheimer's disease: an integrative review and future directions

Two decades of research examining repetition priming in aging and Alzheimer's disease (AD) has yielded a large body of contradictory findings due to differences between studies in participant and task characteristics. Recent research that has employed methodological advances indicates that this form of implicit memory is preserved in healthy aging. When a priming deficit does occur in studies of aging, it is likely a very early signal of neurological disease. Future directions for research in this area include linking priming ability to known risk factors for development of AD, integrating priming measures into clinical neuropsychological assessment batteries, and implementing programs of cognitive retraining that enhance memory using stimulus repetition techniques.

Physical Activity and Leg Strength Predict Decline in Mobility Performance in Older Persons

OBJECTIVES

To assess the extent to which physical activity and leg strength are associated with change in mobility in older persons.

DESIGN

Prospective, observational cohort study.

SETTING

Retirement communities across the Chicago metropolitan area participating in the Rush Memory and Aging Project.

PARTICIPANTS

Eight hundred eighty-six ambulatory older persons without dementia.

MEASUREMENT

Rate of change in mobility.

RESULTS

In a linear mixed-effects model that controlled for age, sex, education, and a term for baseline physical activity, a higher level of physical activity was associated with a slower rate of mobility decline (estimate=0.006, standard error (SE)=0.003, P=.03); each additional hour of physical activity at baseline was associated with an approximately 3% decrease in the rate of mobility decline. In a similar model, a higher level of baseline leg strength was associated with a slower rate of mobility decline (estimate=0.031, SE=0.132, P=.02); each additional unit of leg strength at baseline was associated with an approximately 20% decrease in the rate of mobility decline. In a final model, which included terms for physical activity and leg strength together, both were associated with decline in mobility. Furthermore, both remained associated with mobility even after controlling for body composition, balance, pulmonary function, cognition, history of joint pain, cardiovascular diseases and risk factors, and medications.

CONCLUSION

Physical activity and leg strength are relatively independent predictors of mobility decline in older persons. Although physical activity may improve strength, the beneficial effect of physical activity on mobility is likely to involve other pathways.

Parkinsonian signs and functional disability in old age

Little is known about the association between parkinsonian signs and functional disability. The authors examined the associations between four parkinsonian signs (gait, rigidity, bradykinesia, tremor) and the ability to perform physical and instrumental activities of daily living, in a large cohort of older Rush Memory and Aging Project participants who were free of dementia, Parkinson's disease, and antipsychotic drug use. In a series of logistic regression equations that controlled for age, sex, education, depressive symptoms, cognitive ability, chronic medical conditions, and psychotropic drug use, higher levels of parkinsonian signs were associated with higher levels of disability in performing both physical and instrumental activities of daily living.

Repetition priming and recognition memory in younger and older persons: temporal stability and performance

The dissociation between intact priming and reduced explicit memory in aging has been called into question on the basis of limited information that suggests that priming measures are less reliable than explicit memory measures. No aging study to date, however, has offered a comprehensive examination of the reliability of these measures. Age-related performance and test-retest stability coefficients for multiple priming and explicit memory tasks were compared. Age effects were found on some tasks but not others, and stability was not related to task performance. Stability was similar for implicit versus explicit task instructions, younger versus older persons, and studied versus unstudied items. Results indicate that dissociations between priming and explicit memory performances cannot be accounted for by differential reliability of the measures.

Parkinsonian signs and cognitive function in old age

Studies have shown that parkinsonian signs are related to cognitive function in aging. What remains unclear is whether this association is stronger for some cognitive domains than it is for others, and precisely how much variability in global and specific cognitive functions is explained by the motor signs. We examined the associations between four parkinsonian signs (gait, rigidity, bradykinesia, tremor) and five cognitive domains (episodic memory, semantic memory, working memory, perceptual speed, visuospatial ability) in a large cohort of older persons who were free of Parkinson's disease and dementia and were participating in the Rush Memory and Aging Project. In a series of regression equations that controlled for age, sex, and education, higher levels of three signs (gait, rigidity, and bradykinesia) were related to lower levels of cognitive function, but they accounted for less than 5% of the variance in most measures. The results did not change when the presence of depressive symptoms, diabetes, and hypertension were added to the models. The cross-sectional association between parkinsonian signs and cognitive function did not vary substantially across specific cognitive domains or specific cognitive tests. The results suggest that parkinsonian signs have a modest, but statistically reliable, association with level of cognitive function in old age.

Implicit memory and Alzheimer's disease neuropathology

Explicit memory failure is the defining cognitive feature of Alzheimer's disease and relates to the hallmark neuropathological features (plaques and tangles) of this illness. However, a pattern of preserved and impaired implicit memory has been found in Alzheimer's disease patients that may be explained by the association between the processing demands of certain implicit tests and the level of regional Alzheimer's disease neuropathology. In this study, we tested the hypothesis that these neuropathological features are related to implicit memory--measured by repetition priming--in a test that emphasized conceptual (or meaning-based) cognitive processing, and that the pathological changes are not related to implicit memory in a repetition priming test that emphasized perceptual (or sensory-based) cognitive processing. Subjects were older nuns, priests and brothers participating in the Religious Orders Study who agreed to annual neurological and neuropsychological evaluation for Alzheimer's disease and common neurological conditions of ageing, and brain autopsy at time of death. Explicit memory was measured by seven tests of episodic recall and recognition and converted to a previously established summary measure. Implicit memory was measured by four repetition priming tests. One test, category exemplar priming, emphasized conceptual, or meaning-based cognitive processing. A second test, word-identification priming, emphasized perceptual, or sensory-based cognitive processing. Two additional priming tests, picture-naming and word-stem completion, invoke both conceptual and perceptual processes. Neuritic and diffuse plaques, and neurofibrillary tangles identified by Bielschowsky silver stain, were quantified from five regions separately (frontal, parietal, temporal, entorhinal cortex and the hippocampus) and converted to a previously established summary measure. In linear regression analyses--controlling for age, sex and education--higher levels of Alzheimer's disease neuropathology were related to lower levels of explicit memory proximate to death. Higher levels of neuropathology were also related to lower levels of priming on the category-exemplar test, but were not related to levels of priming on the word-identification, picture-naming, or word-stem completion tests. The results suggest that hallmark indices of Alzheimer's disease neuropathology are associated with performance on priming tests to the extent that conceptual, but not perceptual, processing resources are required.

A longitudinal study of implicit and explicit memory in old persons

Decline in explicit memory with advancing age is a common finding, but it is unclear whether implicit memory (repetition priming) declines or remains stable. Meta-analyses of studies that examined differences between extreme groups (young-old), typically at a single point in time and on a single test, suggest that a mild reduction in priming occurs with advancing age. The authors examined explicit memory and priming, on multiple tests over 4 annual data-collection waves, in a large group of older persons without dementia at baseline. Explicit memory declined significantly, but priming remained stable. Findings indicate that explicit memory and priming are dissociable on the basis of age-related change and that mildly reduced priming is not an inevitable consequence of growing older.