Natural history of mild cognitive impairment in older persons

Identification of prognostic factors to predict cognitive decline of patients with early Alzheimer's disease in the Japanese Alzheimer's Disease Neuroimaging Initiative study

Introduction

The objective of this study was to determine the factors including neuropsychological test performances and cerebrospinal fluid (CSF) biomarkers which can predict disease progression of early Alzheimer's disease (AD) in a Japanese population.

Methods

The group classification on early AD population in both Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI) and North American ADNI (NA-ADNI) was performed using the inclusion criteria including brain amyloid positivity on positron emission tomography or CSF. Participants with early AD from each cohort were stratified into two groups based on a cutoff 1.0 of Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) change at month 24 (m24): participants in "progress group" have CDR-SB change ≥ 1.0 and participants in "stable group" have CDR-SB change < 1.0. Then, we performed identification of prognostic factors from baseline items including neuropsychological scores (Assessment Scale-Cognitive Subscale[ADAS-cog 13], Mini-Mental State Examination (MMSE), CDR, FAQ, and Geriatric Depression Scale ), CSF markers (t-tau, p-tau, and beta-amyloid 1-42), vital signs (body weight, pulse rate, etc.,), by using two statistical approaches, Welch's t-test and simple linear regression by ordinary least squares. Comparisons between participants with J-ADNI and participants with NA-ADNI were also performed.

Results

Trends of CDR-SB changes were very similar between J-ADNI and NA-ADNI early AD population enrolled in this study. Baseline levels of CSF t-tau, p-tau, Mini-Mental State Examination, FAQ, and ADAS-cog13 were identified as prognostic factors in both J-ADNI and NA-ADNI. Based on a detailed subscale analysis on ADAS-cog13, four subscales (Q1: word recall, Q3: construction, Q4: delayed word recall, and Q8: word recognition) were identified as prognostic factors in both J-ADNI and NA-ADNI.

Discussion

Characterizing population with early AD can provide benefits for promoting efficiency in conducting AD clinical trials for disease-modifying treatments. Thus, implementing these prognostic factors into clinical trials may be potentially a good method to enrich participants with early AD who are suitable for evaluating treatment effects.

Risk Aversion and Alzheimer Disease in Old Age

OBJECTIVE

To test the hypothesis that late-life risk aversion is partly a prodromal sign of dementia.

METHODS

The authors' design was a longitudinal clinical-pathologic cohort study. The setting included participants' residences in the Chicago area, and a total of 874 older persons without dementia were enrolled. At baseline, risk aversion was assessed with questions involving choices between certain smaller rewards and uncertain larger rewards. At annual intervals thereafter, participants underwent evaluations that included cognitive testing and diagnosis of mild cognitive impairment (MCI) and dementia. At death, a neuropathologic examination was done to quantify common pathologies linked to dementia.

RESULTS

Risk aversion at study onset ranged from 0.05-0.91 (mean: 0.32, standard deviation: 0.31). During a mean of 4.6 years of follow-up, 123 (of 874) developed dementia. Higher risk aversion was associated with higher dementia incidence (hazard ratio [HR]: 2.08; 95% confidence interval: 1.18, 3.65) and more rapid decline in episodic (estimate: -0.062; standard error [SE]: 0.019; t [3677]: -3.33; p < 0.001) and semantic (estimate: -0.039; SE: 0.015; t [3655]: -2.61; p = 0.009) memory but not in other cognitive systems. Of 702 people without cognitive impairment at baseline, 223 developed incident MCI. Higher risk aversion was associated with higher incidence of MCI (HR: 2.10; 95% confidence interval: 1.34, 3.29) and more rapid episodic memory decline. In 181 neuropathologically examined individuals, higher risk aversion was associated with higher levels of plaques, tangles, and cerebral amyloid angiopathy.

CONCLUSION

The results support the hypothesis that high risk aversion in old age is partly an early sign of the pathology of Alzheimer disease.

Clustering and Switching Patterns in Semantic Fluency and Their Relationship to Working Memory in Mild Cognitive Impairment

Background and Purpose

Semantic verbal fluency test is a neuropsychological assessment that can sensitively detect neuropathological changes. Considering its multifactorial features tapping various cognitive domains such as semantic memory, executive function, and working memory, it is necessary to examine verbal fluency performance in association with underlying cognitive functions. The objective of the current study was to investigate semantic fluency patterns of people with mild cognitive impairment (MCI) based on clustering and switching and their relationship with working memory.

Methods

Twenty-six individuals with MCI and 23 normal elderly adults participated in this study. A semantic verbal fluency test (animal version) was administered and the performance was analyzed using the following measures: number of correct words, cluster size, and number of switches. Scores of digit forward (DF) and backward span tasks were employed as working memory measures.

Results

Analyses of variance revealed significant group differences in the numbers of correct words and switches. Multivariate logistic regression and receiver-operating characteristic analyses showed that the number of switches more sensitively distinguished MCI existence than the number of correct words. Stepwise linear regression analysis showed that DF task and age significantly predicted the number of correct words while only the DF task significantly predicted the number of switches.

Conclusions

Decrement in semantic verbal fluency in MCI seems to be associated with impaired switching abilities. Working memory capacity might serve as the underlying cognitive factor related to decreased verbal fluency in MCI.

Exploring the Correlation between the Cognitive Benefits of Drug Combinations in a Clinical Database and the Efficacies of the Same Drug Combinations Predicted from a Computational Model

Identification of drug combinations that could be effective in Alzheimer’s disease treatment is made difficult by the sheer number of possible combinations. This analysis identifies as potentially therapeutic those drug combinations that rank highest when their efficacy is determined jointly from two independent data sources. Estimates of the efficacy of the same drug combinations were derived from a clinical dataset on cognitively impaired elderly participants and from pre-clinical data, in the form of a computational model of neuroinflammation. Linear regression was used to show that the two sets of estimates were correlated, and to rule out confounds. The ten highest ranking, jointly determined drug combinations most frequently consisted of COX2 inhibitors and aspirin, along with various antihypertensive medications. Ten combinations of from five to nine drugs, and the three-drug combination of a COX2 inhibitor, aspirin, and a calcium-channel blocker, are discussed as candidates for consideration in future pre-clinical and clinical studies.

Motoric cognitive risk syndrome and predictors of transition to dementia: A multicenter study

INTRODUCTION

To report clinical predictors of transition to dementia in motoric cognitive risk syndrome (MCR), a predementia syndrome characterized by cognitive complaints and slow gait.

METHODS

We examined if cognitive or motoric impairments predicted transition to dementia in 610 older adults with MCR from three cohorts. Association of cognitive (logical memory, clinical dementia rating, cognitive complaint severity, and Mini-Mental State Examination) and motoric factors (gait velocity) with dementia risk was computed using Cox models.

RESULTS

There were 156 incident dementias (134 Alzheimer's disease). In the pooled sample, logical memory (adjusted hazard ratio [aHR] 0.91), cognitive complaint severity (aHR 1.53), and Mini-Mental State Examination (aHR 0.75) predicted transition of MCR to dementia. Clinical dementia rating score ≥0.5 predicted dementia (aHR 3.18) in one cohort. Gait velocity did not predict dementia.

DISCUSSION

While MCR is a motoric-based predementia syndrome, severity of cognitive but not motoric impairments predicts conversion to dementia.

Scam Awareness Related to Incident Alzheimer Dementia and Mild Cognitive Impairment: A Prospective Cohort Study

BACKGROUND

Decreased scam awareness may be an early indicator of impending Alzheimer dementia and its precursor, mild cognitive impairment, but prior studies have not systematically examined the associations between scam awareness and adverse cognitive outcomes.

OBJECTIVE

To test the hypothesis that low scam awareness is associated with increased risk for incident Alzheimer dementia, mild cognitive impairment, and Alzheimer disease pathology in the brain.

DESIGN

Prospective cohort study of aging.

SETTING

Community-based study in the greater Chicago metropolitan area.

PARTICIPANTS

935 older persons initially free of dementia.

MEASUREMENTS

Scam awareness was measured via questionnaire, incident Alzheimer dementia and mild cognitive impairment were documented in detailed annual cognitive and clinical evaluations, and Alzheimer disease neuropathology was quantified after death among a subset of persons who died (n = 264). Proportional hazards models examined associations between scam awareness and incident Alzheimer dementia and mild cognitive impairment. Regression models examined associations between scam awareness and Alzheimer disease pathology, particularly β-amyloid burden and tau tangle density.

RESULTS

During a mean of about 6 years (SD, 2.4) of observation, 151 persons (16.1%) developed Alzheimer dementia. Low scam awareness was associated with increased risk for Alzheimer dementia (hazard ratio [HR], 1.56 [95% CI, 1.21 to 2.01]; P < 0.001), such that each 1-unit increase in scam score (indicating lower awareness) was associated with about a 60% increase in dementia risk. Low scam awareness was also associated with increased risk for mild cognitive impairment (HR, 1.47 [CI, 1.20 to 1.81]; P < 0.001). These associations persisted even after adjustment for global cognitive function. Finally, low scam awareness was associated with a higher burden of Alzheimer pathology in the brain, particularly β-amyloid (estimated increase [±SE] in β-amyloid per 1-unit increase in scam score, 0.22 ± 0.10 unit; P = 0.029).

LIMITATION

The measure of scam awareness used here is too weak for prediction at the individual level.

CONCLUSION

Low scam awareness among older persons is a harbinger of adverse cognitive outcomes and is associated with Alzheimer disease pathology in the brain.

PRIMARY FUNDING SOURCE

National Institute on Aging.

Musical and Cognitive Abilities in Older Adults with Mild Cognitive Impairment

The objective of this cross-sectional study was to determine the extent and nature of self-reported musical abilities in persons with mild cognitive impairment (MCI). We recruited 60 older adults with a diagnosis of MCI from the Alzheimer's disease Core Center. We evaluated self-reported musical abilities using the Goldsmiths General Musical Sophistication Index. We examined correlations between musical abilities and neuropsychological measures of verbal learning and memory, processing speed, executive function, verbal fluency, naming and visuoconstructive abilities, while controlling for key demographic and participant characteristics. Older adults with MCI reported varying degrees of musical abilities. Nearly half of participants reported that they did not engage in regular, daily practice of a musical instrument. When adjusting for key demographic and participant characteristics, we found modest associations between four musical ability subfactors (active engagement, perceptual abilities, musical training and emotional engagement with music) with three cognitive abilities: verbal fluency, executive function and verbal naming. Except for the emotional engagement with music subfactor, none of the remaining musical ability subfactors correlated with any demographic or participant characteristics. While our study findings provided further support for the relationship between musical and cognitive abilities in older adults with MCI, this relationship warrants further investigation.

Beta-amyloid pathology in human brain microvessel extracts from the parietal cortex: relation with cerebral amyloid angiopathy and Alzheimer's disease

Several pieces of evidence suggest that blood-brain barrier (BBB) dysfunction is implicated in the pathophysiology of Alzheimer's disease (AD), exemplified by the frequent occurrence of cerebral amyloid angiopathy (CAA) and the defective clearance of Aβ peptides. However, the specific role of brain microvascular cells in these anomalies remains elusive. In this study, we validated by Western, ELISA and immunofluorescence analyses a procedure to generate microvasculature-enriched fractions from frozen samples of human cerebral cortex. We then investigated Aβ and proteins involved in its clearance or production in microvessel extracts generated from the parietal cortex of 60 volunteers in the Religious Orders Study. Volunteers were categorized as AD (n = 38) or controls (n = 22) based on the ABC scoring method presented in the revised guidelines for the neuropathological diagnosis of AD. Higher ELISA-determined concentrations of vascular Aβ40 and Aβ42 were found in persons with a neuropathological diagnosis of AD, in apoE4 carriers and in participants with advanced parenchymal CAA, compared to respective age-matched controls. Vascular levels of two proteins involved in Aβ clearance, ABCB1 and neprilysin, were lower in persons with AD and positively correlated with cognitive function, while being inversely correlated to vascular Aβ40. In contrast, BACE1, a protein necessary for Aβ production, was increased in individuals with AD and in apoE4 carriers, negatively correlated to cognitive function and positively correlated to Aβ40 in microvessel extracts. The present report indicates that concentrating microvessels from frozen human brain samples facilitates the quantitative biochemical analysis of cerebrovascular dysfunction in CNS disorders. Data generated overall show that microvessels extracted from individuals with parenchymal CAA-AD contained more Aβ and BACE1 and less ABCB1 and neprilysin, evidencing a pattern of dysfunction in brain microvascular cells contributing to CAA and AD pathology and symptoms.

Associations of amygdala volume and shape with transactive response DNA-binding protein 43 (TDP-43) pathology in a community cohort of older adults

Transactive response DNA-binding protein 43 (TDP-43) pathology is common in old age and is strongly associated with cognitive decline and dementia above and beyond contributions from other neuropathologies. TDP-43 pathology in aging typically originates in the amygdala, a brain region also affected by other age-related neuropathologies such as Alzheimer's pathology. The purpose of this study was two-fold: to determine the independent effects of TDP-43 pathology on the volume, as well as shape, of the amygdala in a community cohort of older adults, and to determine the contribution of amygdala volume to the variance of the rate of cognitive decline after accounting for the contributions of neuropathologies and demographics. Cerebral hemispheres from 198 participants of the Rush Memory and Aging Project and the Religious Orders Study were imaged with MRI ex vivo and underwent neuropathologic examination. Measures of amygdala volume and shape were extracted for all participants. Regression models controlling for neuropathologies and demographics showed an independent negative association of TDP-43 with the volume of the amygdala. Shape analysis revealed a unique pattern of amygdala deformation associated with TDP-43 pathology. Finally, mixed-effects models showed that amygdala volume explained an additional portion of the variance of the rate of decline in global cognition, episodic memory, semantic memory, and perceptual speed, above and beyond what was explained by demographics and neuropathologies.

Single-cell transcriptomic analysis of Alzheimer's disease

Alzheimer's disease is a pervasive neurodegenerative disorder, the molecular complexity of which remains poorly understood. Here, we analysed 80,660 single-nucleus transcriptomes from the prefrontal cortex of 48 individuals with varying degrees of Alzheimer's disease pathology. Across six major brain cell types, we identified transcriptionally distinct subpopulations, including those associated with pathology and characterized by regulators of myelination, inflammation, and neuron survival. The strongest disease-associated changes appeared early in pathological progression and were highly cell-type specific, whereas genes upregulated at late stages were common across cell types and primarily involved in the global stress response. Notably, we found that female cells were overrepresented in disease-associated subpopulations, and that transcriptional responses were substantially different between sexes in several cell types, including oligodendrocytes. Overall, myelination-related processes were recurrently perturbed in multiple cell types, suggesting that myelination has a key role in Alzheimer's disease pathophysiology. Our single-cell transcriptomic resource provides a blueprint for interrogating the molecular and cellular basis of Alzheimer's disease.

Relation of Serum Plasmalogens and APOE Genotype to Cognition and Dementia in Older Persons in a Cross-Sectional Study

Using a community sample of 1205 elderly persons, we investigated the associations and potential interactions between Apolipoprotein E (APOE) genotype and serum phosphatidylethanolamine (PlsEtn) on cognition and dementia. For each person, APOE genotype, PlsEtn Biosynthesis value (PBV, the combination of three key PlsEtn species), cognition (the combination of five specific cognitive domains), and diagnosis of dementia was determined. APOE genotype and PBV were observed to be non-interacting (p > 0.05) and independently associated with cognition: APOE (relative to ε3ε3:ε2ε3 (Coef = 0.14, p = 4.2 × 10⁻²); ε3ε4/ε4ε4 (Coef = −0.22, p = 6.2 × 10⁻⁵); PBV (Coef = 0.12, p = 1.7 × 10⁻⁷) and dementia: APOE (relative to ε3ε3:ε2ε3 (Odds Ratio OR = 0.44, p = 3.0 × 10⁻²); ε3ε4/ε4ε4 (OR = 2.1, p = 2.2 × 10⁻⁴)); PBV (OR = 0.61, p = 3.3 × 10⁻⁶). Associations are expressed per standard deviation (SD) and adjusted for serum lipids and demographics. Due to the independent and non-interacting nature of the APOE and PBV associations, the prevalence of dementia in APOE ε3ε4/ε4ε4 persons with high PBV values (>1 SD from mean) was observed to be the same as APOE ε3ε3 persons (14.3% versus 14.0%). Similarly, the prevalence of dementia in APOE ε3ε3 persons with high PBV values was only 5.7% versus 6.7% for APOE ε2ε3 persons. The results of these analyses indicate that the net effect of APOE genotype on cognition and the prevalence of dementia is dependent upon the plasmalogen status of the person.

Association Between Periodontitis and Cognitive Impairment in Adults: A Systematic Review

Periodontitis is an oral inflammatory disease and may contribute to low-grade systemic inflammation. Based on the contribution of periodontitis to systemic inflammation and the potential role of systemic inflammation in neuroinflammation, many epidemiological studies have investigated a possible association between periodontitis and mild cognitive impairment or dementia. The purpose of this study was to evaluate the clinical/epidemiological evidence regarding the association between periodontitis and cognitive decline in adult patients. A search conducted between September and October 2018 was performed in the electronic databases PubMed, Scopus, Web of Science, The Cochrane Library, LILACS, OpenGrey, and Google Scholar, with no publication date or language restrictions. Analytical observational studies in adults (P—Participants), with (E—Exposure) and without periodontitis (C—Comparison) were included in order to determine the association between periodontitis and cognitive decline (O—Outcome). The search identified 509 references, of which eight observational studies were accorded with the eligibility criteria and evaluated. The results should, however, be interpreted cautiously due to the limited number of studies. This systematic review points to the need for further well-designed studies, such as longitudinal observational studies with control of modifiable variables, as diagnostic criteria and time since diagnosis of periodontitis and cognitive impairment, to confirm the proposed association.

Incident Mobility Disability, Mild Cognitive Impairment, and Mortality in Community-Dwelling Older Adults

BACKGROUND/AIMS

Mobility disability and mild cognitive impairment (MCI) are common in aging and both are associated with risk of death. This study tested the hypothesis that risk of death differs by the order in which mobility disability and MCI occurred.

METHODS

One thousand two hundred and sixty-two community-dwelling older adults were unimpaired at baseline and followed annually. Mobility disability was based on measured gait speed, and MCI was based on cognitive performance tests. A multistate Cox model simultaneously examined incidences of mobility disability and MCI to determine whether the order of their occurrence is differentially associated with risk of death.

RESULTS

The average age was 75.3 years and 70% were female. While mobility disability occurred more frequently than incident MCI, the subsequent risk of death was higher in participants who developed MCI alone compared to those who developed mobility disability alone (hazard ratio [HR] 1.70, p = 0.018). Of the participants who initially developed mobility disability, about half subsequently developed MCI that doubled their risk of death (HR 2.17, p < 0.001). By contrast, over two-third who developed MCI subsequently developed mobility disability, which did not further increase their risk of death.

CONCLUSION

Mobility disability occurs more frequently in community-dwelling older adults, but MCI is more strongly associated with mortality.

Patients with Alzheimer's disease who carry the APOE ε4 allele benefit more from physical exercise

Introduction

Our group has completed an exercise study of 200 patients with mild Alzheimer's disease. We found improvements in cognitive, neuropsychiatric, and physical measures in the participants who adhered to the protocol. Epidemiological studies in healthy elderly suggest that exercise preserves cognitive and physical abilities to a higher extent in APOE ε4 carriers.

Methods

In this post hoc subgroup analysis study, we investigated whether the beneficial effect of an exercise intervention in patients with mild AD was dependent on the patients' APOE genotype.

Results

We found that patients who were APOE ε4 carriers benefitted more from the exercise intervention by preservation of cognitive performance and improvement in physical measures.

Discussion

This exploratory study establishes a possible connection between the beneficial effects of exercise in AD and the patients' APOE genotype. These findings, if validated, could greatly impact the clinical management of patients with AD and those at risk for developing AD.

Frontal Cortex Epigenetic Dysregulation During the Progression of Alzheimer's Disease

Although the frontal cortex plays an important role in cognitive function and undergoes neuronal dysfunction in Alzheimer's disease (AD), the factors driving these cellular alterations remain unknown. Recent studies suggest that alterations in epigenetic regulation play a pivotal role in this process in AD. We evaluated frontal cortex histone deacetylase (HDAC) and sirtuin (SIRT) levels in tissue obtained from subjects with a premortem diagnosis of no-cognitive impairment (NCI), mild cognitive impairment (MCI), mild to moderate AD (mAD), and severe AD (sAD) using quantitative western blotting. Immunoblots revealed significant increases in HDAC1 and HDAC3 in MCI and mAD, followed by a decrease in sAD compared to NCI. HDAC2 levels remained stable across clinical groups. HDAC4 was significantly increased in MCI and mAD, but not in sAD compared to NCI. HDAC6 significantly increased during disease progression, while SIRT1 decreased in MCI, mAD, and sAD compared to NCI. HDAC1 levels negatively correlated with perceptual speed, while SIRT1 positively correlated with perceptual speed, episodic memory, global cognitive score, and Mini-Mental State Examination. HDAC1 positively, while SIRT1 negatively correlated with cortical neurofibrillary tangle counts. These findings suggest that dysregulation of epigenetic proteins contribute to neuronal dysfunction and cognitive decline in the early stage of AD.

The incidence of mild cognitive impairment: A systematic review and data synthesis

Introduction

Incidence estimates of mild cognitive impairment (MCI) range widely. We obtained contemporary age-specific MCI incidence rates and examined sources of heterogeneity.

Methods

We conducted a systematic review of population-based studies from the Americas, Europe, and Australia using restrictive inclusion criteria to limit heterogeneity. Incidence was examined using 5-year age categories for MCI and amnestic/nonamnestic subtypes. Data were synthesized using quantitative and qualitative descriptive analyses and quantitative meta-analyses.

Results

Meta-analysis estimates (95% CI) of MCI incidence per 1000 person-years were 22.5 (5.1-51.4) for ages 75-79y, 40.9 (7.7-97.5) for ages 80-84y, and 60.1 (6.7-159.0) for ages 85+y. Despite restrictive inclusion criteria, considerable heterogeneity (measured by I²) remained. Meta-analysis findings and simple descriptive statistics were consistent and supported by qualitative review.

Discussion

Heterogeneity in MCI incidence estimates persisted across age-specific estimates from population samples, likely reflecting differences in populations and methods. Incidence rate ranges are important to consider with summary point estimates.

Association of Financial Literacy With Hospitalization in Community-dwelling Older Adults

BACKGROUND

Lowering the likelihood of hospitalization in older adults is a major public health goal for modern health care systems. Emerging data suggest that financial literacy is an important determinant of health outcomes in old age, but the relationship with hospitalization has not been explored.

OBJECTIVE

To test the hypothesis that better financial literacy is related to lower risk of hospitalization in older persons.

DESIGN

Prospective cohort study.

PARTICIPANTS

Data came from community-dwelling older adults (n=388) without dementia enrolled in the Rush Memory and Aging Project.

MAIN MEASURES

Participants underwent detailed assessment of financial literacy and cognition. Data on hospitalizations were obtained from linked Medicare claims records (MedPAR file).

RESULTS

Over an average of 1.8 years, 117 participants (30%) were hospitalized, and a third of those hospitalized experienced multiple hospitalizations. In a modified Poisson regression model adjusted for age, sex, education, and cognition, better financial literacy was associated with lower risk of hospitalization. In a model further adjusted for income, physical activity, body mass index, smoking, social network size, chronic conditions, basic and instrumental activities of daily living disability, and depressive symptoms, the association was unchanged. Secondary analyses showed the association was primarily driven by conceptual knowledge rather than numeracy.

CONCLUSIONS

Higher financial literacy is related to a lower risk of hospitalization in older persons without dementia, after adjusting for cognitive, health, functional, and socioeconomic factors. The ability to understand and utilize financial concepts may represent a potentially modifiable risk factor for hospitalization in later life.

CPAP Adherence May Slow 1-Year Cognitive Decline in Older Adults with Mild Cognitive Impairment and Apnea

BACKGROUND/OBJECTIVES

Obstructive sleep apnea (OSA) has been linked to an increased risk for Alzheimer's disease (AD), but little prospective evidence exists on the effects of OSA treatment in preclinical AD. The objective was to determine if continuous positive airway pressure (CPAP) treatment adherence, controlling for baseline differences, predicts cognitive and everyday function after 1 year in older adults with mild cognitive impairment (MCI) and to determine effect sizes for a larger trial.

DESIGN

Quasi-experimental pilot clinical trial with CPAP adherence defined as CPAP use 4 hours or more per night over 1 year.

SETTING

Sleep and geriatric clinics and community.

PARTICIPANTS

Older adults, aged 55 to 89 years, with an apnea-hypopnea index of 10 or higher participated: (1) MCI, OSA, and CPAP adherent (MCI +CPAP), n = 29; and (2) MCI, OSA, CPAP nonadherent (MCI -CPAP), n = 25.

INTERVENTION

CPAP.

MEASUREMENTS

The primary cognitive outcome was memory (Hopkins Verbal Learning Test-Revised), and the secondary cognitive outcome was psychomotor/cognitive processing speed (Digit Symbol subtest from the Wechsler Adult Intelligence Scale Substitution Test). Secondary function and progression measures were the Everyday Cognition, Alzheimer's Disease Cooperative Study-Clinical Global Impression of Change Scale, and Clinical Dementia Rating.

RESULTS

Statistically significant improvements in psychomotor/cognitive processing speed in the MCI +CPAP group vs the MCI -CPAP group were observed at 1 year after adjustment for age, race, and marital status (parameter estimate = 1.68; standard error = 0.47; 95% confidence interval = 0.73-2.62), with a 6-month effect size (ES) of 0.46 and a 1-year ES of 1.25. There were small to moderate ESs for memory (ES 0.20, 6 mo), attention (ES 0.25, 1 y), daytime sleepiness (ES 0.33, 6 mo and ES 0.22, 1 y), and everyday function (ES 0.50, 6 mo) favoring the MCI +CPAP group vs the MCI -CPAP group.

CONCLUSION

Controlling for baseline differences, 1 year of CPAP adherence in MCI +OSA significantly improved cognition, compared with a nonadherent control group, and may slow the trajectory of cognitive decline.

TRIAL REGISTRATION NUMBER

Memories; NCT01482351; https://clinicaltrials.gov/ct2/show/NCT01482351?cond=MCI+and+OSA&rank=1 J Am Geriatr Soc 67:558-564, 2019.

In vivo hippocampal subfield shape related to TDP-43, amyloid beta, and tau pathologies

Despite advances in the development of biomarkers for Alzheimer's disease (AD), accurate ante-mortem diagnosis remains challenging because a variety of neuropathologic disease states can coexist and contribute to the AD dementia syndrome. Here, we report a neuroimaging study correlating hippocampal deformity with regional AD and transactive response DNA-binding protein of 43 kDA pathology burden. We used hippocampal shape analysis of ante-mortem T1-weighted structural magnetic resonance imaging images of 42 participants from two longitudinal cohort studies conducted by the Rush Alzheimer's Disease Center. Surfaces were generated for the whole hippocampus and zones approximating the underlying subfields using a previously developed automated image-segmentation pipeline. Multiple linear regression models were constructed to correlate the shape with pathology measures while accounting for covariates, with relationships mapped out onto hippocampal surface locations. A significant relationship existed between higher paired helical filaments-tau burden and inward hippocampal shape deformity in zones approximating CA1 and subiculum which persisted after accounting for coexisting pathologies. No significant patterns of inward surface deformity were associated with amyloid-beta or transactive response DNA-binding protein of 43 kDA after including covariates. Our findings indicate that hippocampal shape deformity measures in surface zones approximating CA1 may represent a biomarker for postmortem AD pathology.

Cognitive impairment and postural control deficit in adults with Type 2 diabetes

BACKGROUND

Diseases induced by metabolic disorders, eg, Type 2 diabetes, has recently been linked to both sensory and motor deficit in the absence of a formal clinical diagnosis of peripheral neuropathy. Studies have demonstrated mild cognitive impairment in diabetic patients, which also plays a role in one's loss of ability to successfully perform basic motor activities. This project focused on evaluating cognitive function while maintaining balance. We hypothesized that simultaneous cognitive and motor deficit would occur among adults with Type 2 diabetes versus healthy age- and sex-matched control during a balance task.

METHODS

A sample of 10 Type 2 diabetes patients and 10 age-matched and sex-matched controls underwent a series of sensory, motor, cognitive, and cognitive-motor evaluations. Blood pressure and A_1c levels were assessed.

RESULTS

Significantly lower cognitive function scores, particularly in the domain of working memory, were exhibited in the diabetic group than controls. Balance in the diabetic group was overall poorer in both single- and dual-tasks than controls. When diabetic patients were asked to verbally recall different words while maintaining their balance, their accuracy rate was significantly lower than controls. Some health state measures were found to co-vary with motor function. Increased body mass index in the diabetic group did not account for motor function deficit.

SIGNIFICANCE

Our data suggest that: (1) systemic deficit beyond tactile dysfunction and increased body mass index contribute to reduced motor function in diabetes, and (2) both balance and working memory functions are simultaneously impaired in patients with Type 2 diabetes.

The Development and Validation of an Online Spatial Network Measure

Planning is an essential cognitive process of executive functions and is considered as one of the most important brain functions. Planning has been extensively studied in the field of neuropsychology, but there is a lack of computerized assessment tools of planning ability that are easily accessible to researchers and clinicians. The present study aims to validate a newly developed online spatial network test that is designed for both clinical and nonclinical populations. Exploratory factor analysis revealed a unidimensional factorial structure with moderate to high internal consistency in the test. Two-parameter logistic item response theory analysis showed acceptable item and model fit and no violation of the local independence assumption. The overall success rate exhibited a positive correlation with the performance of planning before attempting to solve the items. After correcting for attenuation, moderate to high correlations were found between the spatial network test and the International Cognitive Ability Resource 16 short form cognitive ability test and the automated perceptual maze test, respectively, demonstrating convergent, discriminant, and criterion validity. Future directions and potential applications of the spatial network test as an assessment tool to measure planning for researchers and clinicians are discussed in the end.

Subtypes Based on Neuropsychological Performance Predict Incident Dementia: Findings from the Rush Memory and Aging Project

BACKGROUND

In a previous report, we used latent class analysis (LCA) to identify natural subgroups of older adults in the Einstein Aging Study (EAS) based on neuropsychological performance. These subgroups differed in demographics, genetic profile, and prognosis. Herein, we assess the generalizability of these findings to an independent sample, the Rush Memory and Aging Project (MAP), which used an overlapping, but distinct neuropsychological battery.

OBJECTIVE

Our aim was to identify the association of natural subgroups based on neuropsychological performance in the MAP cohort with incident dementia and compare them with the associations identified in the EAS.

METHODS

MAP is a community-dwelling cohort of older adults living in the northeastern Illinois, Chicago. Latent class models were applied to baseline scores of 10 neuropsychological measures across 1,662 dementia-free MAP participants. Results were compared to prior findings from the EAS.

RESULTS

LCA resulted in a 5-class model: Mixed-Domain Impairment (n = 71, 4.3%), Memory-specific-Impairment (n = 274, 16.5%), Average (n = 767, 46.1%), Frontal Impairment (n = 222, 13.4%), and a class of Superior Cognition (n = 328, 19.7%). Similar to the EAS, the Mixed-Domain Impairment, the Memory-Specific Impairment, and the Frontal Impairment classes had higher risk of incident Alzheimer's disease when compared to the Average class. By contrast, the Superior Cognition had a lower risk of Alzheimer's disease when compared to the Average class.

CONCLUSIONS

Natural cognitive subgroups in MAP are similar to those identified in EAS. These similarities, despite study differences in geography, sampling strategy, and cognitive tests, suggest that LCA is capable of identifying classes that are not limited to a single sample or a set of cognitive tests.

Analysis of cognitive performance and polymorphisms of SORL1, PVRL2, CR1, TOMM40, APOE, PICALM, GWAS_14q, CLU, and BIN1 in patients with mild cognitive impairment and cognitively healthy controls

INTRODUCTION

Alzheimer disease risk polymorphisms have been studied in patients with dementia, but have not yet been explored in mild cognitive impairment (MCI) in our population; nor have they been addressed in relation to cognitive variables, which can be predictive biomarkers of disease.

OBJECTIVE

To evaluate cognitive performance and presence of polymorphisms of the genes SORL1(rs11218304), PVRL2(rs6859), CR1(rs6656401), TOMM40(rs2075650), APOE (isoforms ɛ2, ɛ3, ɛ4), PICALM(rs3851179), GWAS_14q(rs11622883), BIN1(rs744373), and CLU (rs227959 and rs11136000) in patients with MCI and healthy individuals.

METHODOLOGY

We performed a cross-sectional, exploratory, descriptive study of a prospective cohort of participants selected by non-probabilistic sampling, evaluated with neurological, neuropsychological, and genetic testing, and classified as cognitively healthy individuals and patients with MCI. Cognition was evaluated with the Neuronorma battery and analysed in relation to the polymorphic variants by means of measures of central tendency, confidence intervals, and nonparametric statistics.

RESULTS

We found differences in performance in language and memory tasks between carriers and non-carriers of BIN1, CLU, and CR1 variants and a trend toward poor cognitive performance for PICALM, GWAS_14q, SORL1, and PVRL2 variants; the APOE and TOMM40 variants were not associated with poor cognitive performance.

DISCUSSION

Differences in cognitive performance associated with these polymorphic variants may suggest that the mechanisms regulating these genes could have an effect on cognition in the absence of dementia; however, this study was exploratory and hypotheses based on these results must be explored in larger samples.

Antecedents and consequences of unawareness of memory impairment in dementia

OBJECTIVE

To assess the prevalence, antecedents, and consequences of unawareness of memory impairment in dementia.

METHOD

Persons (n = 1,862) from a geographically defined community without dementia at enrollment subsequently underwent clinical classification (248 with dementia, 611 with mild cognitive impairment, 1,003 with no cognitive impairment), memory testing, and self-appraisal of memory. Memory performance was regressed on self-appraised memory, and the residuals served as an index of memory awareness. After clinical classification, participants completed brief cognitive testing at 3-year intervals for up to 15 years.

RESULTS

When unawareness was defined as a score at or below thresholds ranging from the 15th to 25th percentiles, it was more common in dementia (67%-83%) and mild cognitive impairment (15%-33%) than in no cognitive impairment (2%-6%; all p < .001). A continuous measure of awareness (M = 0.00, SD = 0.61) was reduced by 0.37-unit in mild cognitive impairment (SE = 0.04, p < .001) and 1.04-unit in dementia (SE = 0.06), p < .001) compared with those without cognitive impairment, and these associations were weaker in Black persons than White persons (estimate for dementia by race = 0.37, SE = 0.12, p = .003; estimate for mild cognitive impairment by race = 0.30, SE = 0.08, p < .001). Higher premorbid neuroticism was associated with better memory awareness in dementia. Higher memory awareness was not related to mortality in mild cognitive impairment or dementia but had a marginal association with slower cognitive decline in mild cognitive impairment.

CONCLUSIONS

Unawareness of memory impairment is a common manifestation of dementia, particularly in White persons, but is not strongly related to adverse disease outcomes. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

HDAC2 dysregulation in the nucleus basalis of Meynert during the progression of Alzheimer's disease

AIMS

Alzheimer's disease (AD) is characterized by degeneration of cholinergic basal forebrain (CBF) neurons in the nucleus basalis of Meynert (nbM), which provides the major cholinergic input to the cortical mantle and is related to cognitive decline in patients with AD. Cortical histone deacetylase (HDAC) dysregulation has been associated with neuronal degeneration during AD progression. However, whether HDAC alterations play a role in CBF degeneration during AD onset is unknown. We investigated global HDAC protein levels and nuclear HDAC2 immunoreactivity in tissue containing the nbM, changes and their association with neurofibrillary tangles (NFTs) during the progression of AD.

METHODS

We used semi-quantitative western blotting and immunohistochemistry to evaluate HDAC and sirtuin (SIRT) levels in individuals that died with a premortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), mild/moderate AD (mAD) or severe AD (sAD). Quantitative immunohistochemistry was used to identify HDAC2 protein levels in individual cholinergic nbM nuclei and their colocalization with the early phosphorylated tau marker AT8, the late-stage apoptotic tau marker TauC3 and Thioflavin-S, a marker of β-pleated sheet structures in NFTs.

RESULTS

In AD patients, HDAC2 protein levels were dysregulated in the basal forebrain region containing cholinergic neurons of the nbM. HDAC2 nuclear immunoreactivity was reduced in individual cholinergic nbM neurons across disease stages. HDAC2 nuclear reactivity correlated with multiple cognitive domains and with NFT formation.

CONCLUSIONS

These findings suggest that HDAC2 dysregulation contributes to cholinergic nbM neuronal dysfunction, NFT pathology, and cognitive decline during clinical progression of AD.

Subjective Cognitive Decline Prediction of Mortality: Results from the Einstein Aging Study

BACKGROUND

The relation of pre-dementia stages to mortality has not been fully explored. Previous work examining subjective cognitive decline (SCD) and mortality is limited and mixed regarding methods used and consistency of findings.

OBJECTIVE

To examine SCD and mortality in a longitudinal, community-based cohort, using item response theory (IRT) methodology to form a composite SCD measure. Also, to assess whether this relationship was independent of clinical cognitive status.

METHODS

The Einstein Aging Study is a diverse longitudinal cohort of adults aged ≥70. SCD items were extracted from baseline CERAD questionnaires and a composite score was formed using IRT methodology. A total of 1,741 participants with complete data were clinically diagnosed as cognitively normal, or as having amnestic mild cognitive impairment (aMCI), nonamnestic mild cognitive impairment (naMCI), or dementia. 645 deaths occurred over a period of 8,912 person-years of follow-up. Cox proportional hazard models predicted time to death adjusting for covariates.

RESULTS

A one standard deviation unit increase in level of SCD was associated with >20% higher risk of mortality. However, when models were adjusted for clinical cognitive status, the association was no longer significant. Both dementia and aMCI predicted mortality. Furthermore, when analyses focused only on those without cognitive impairment, SCD level did not predict mortality.

CONCLUSIONS

The association of SCD with mortality may be due to the association of SCD with clinical cognitive status. Thus, SCD may be used as a community-based screen to initially identify those with cognitive impairment who may be at greatest risk for death.

Patterns of cognitive function in middle-aged and elderly Chinese adults-findings from the EMCOA study

Background

The principal aim of this study was to demonstrate the gender-specific cognitive patterns among middle-aged and elderly Chinese adults, investigate the risk factors on global and domain-specific cognitive performance in men and women, respectively, and report demographically adjusted norms for cognitive tests.

Methods

The Effects and Mechanism of Cholesterol and Oxysterol on Alzheimer’s disease (EMCOA) study enrolled 4573 participants aged 50–70 years in three Chinese cities. All participants underwent an extensive neuropsychological test battery. Composite scores for specific domains were derived from principal component analysis (PCA). Multivariate linear regression models were used to determine gender-specific risk factors and demographically adjusted normative data.

Results

Three cognitive domains of verbal memory, attention/processing speed/executive function, and cognitive flexibility were extracted. A female advantage in verbal memory was observed regardless of age, whereas men tended to outperform women in global cognition and attention/processing speed/executive function. The effects of education on women were more substantial than men for general cognition and attention/processing speed/executive function. For all the cognitive tests, regression-based and demographically adjusted normative data were calculated.

Conclusions

There is a need for gender-specific intervention strategies for operationalizing cognitive impairment.

Trial registration

EMCOA, ChiCTR-OOC-17011882. Retrospectively registered on 5 July 2017.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0421-8) contains supplementary material, which is available to authorized users.

Cognitive composite score association with Alzheimer's disease plaque and tangle pathology

BACKGROUND

Cognitive composite scores are used as the primary outcome measures for Alzheimer's disease (AD) prevention trials; however, the extent to which these composite measures correlate with AD pathology has not been fully investigated. Since many on-going AD prevention studies are testing therapies that target either amyloid or tau, we sought to establish an association between a cognitive composite score and the underlying pathology of AD.

METHODS

Data from 192 older deceased and autopsied persons from the Rush Religious Order Study were used in this study. All participants were classified at their initial evaluations with a clinical diagnosis of no cognitive impairment (NCI). Of these individuals, 105 remained NCI at the time of their death while the remaining 87 progressed to mild cognitive impairment (MCI) or AD. A cognitive composite score composed of eight cognitive tests was used as the outcome measure. Individuals were classified into groups based on Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropathological diagnosis and Braak stage.

RESULTS

The rate of annualized composite score decline was significantly greater for the high CERAD (p < 0.001, d = 0.56) and Braak (p < 0.001, d = 0.55) groups compared with the low CERAD and Braak groups, respectively. Mixed-model repeated measure (MMRM) analyses revealed a significantly greater difference in composite score change from baseline for the high CERAD group relative to the low CERAD group after 5 years (Δ = -2.74, 95% confidence interval (CI) -5.01 to -0.47; p = 0.02). A similar analysis between low and high Braak stage groups found no significant difference in change from baseline (Δ = -0.69, 95% CI -3.03 to 1.66; p = 0.56).

CONCLUSIONS

These data provide evidence that decreased cognitive composite scores were significantly associated with increased AD pathology and provide support for the use of cognitive composite scores in AD prevention trials.

Pretangle pathology within cholinergic nucleus basalis neurons coincides with neurotrophic and neurotransmitter receptor gene dysregulation during the progression of Alzheimer's disease

Cholinergic basal forebrain neurons of the nucleus basalis of Meynert (nbM) regulate attentional and memory function and are exquisitely prone to tau pathology and neurofibrillary tangle (NFT) formation during the progression of Alzheimer's disease (AD). nbM neurons require the neurotrophin nerve growth factor (NGF), its cognate receptor TrkA, and the pan-neurotrophin receptor p75NTR for their maintenance and survival. Additionally, nbM neuronal activity and cholinergic tone are regulated by the expression of nicotinic (nAChR) and muscarinic (mAChR) acetylcholine receptors as well as receptors modulating glutamatergic and catecholaminergic afferent signaling. To date, the molecular and cellular relationships between the evolution of tau pathology and nbM neuronal survival remain unknown. To address this knowledge gap, we profiled cholinotrophic pathway genes within nbM neurons immunostained for pS422, a pretangle phosphorylation event preceding tau C-terminal truncation at D421, or dual-labeled for pS422 and TauC3, a later stage tau neo-epitope revealed by this same C-terminal truncation event, via single-population custom microarray analysis. nbM neurons were obtained from postmortem tissues from subjects who died with an antemortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), or mild/moderate AD. Quantitative analysis revealed significant downregulation of mRNAs encoding TrkA as well as TrkB, TrkC, and the Trk-mediated downstream pro-survival kinase Akt in pS422+ compared to unlabeled, pS422-negative nbM neurons. In addition, pS422+ neurons displayed a downregulation of transcripts encoding NMDA receptor subunit 2B, metabotropic glutamate receptor 2, D2 dopamine receptor, and β1 adrenoceptor. By contrast, transcripts encoding p75NTR were downregulated in dual-labeled pS422+/TauC3+ neurons. Appearance of the TauC3 epitope was also associated with an upregulation of the α7 nAChR subunit and differential downregulation of the β2 nAChR subunit. Notably, we found that gene expression patterns for each cell phenotype did not differ with clinical diagnosis. However, linear regression revealed that global cognition and Braak stage were predictors of select transcript changes within both unlabeled and pS422+/TauC3- neurons. Taken together, these cell phenotype-specific gene expression profiling data suggest that dysregulation of neurotrophic and neurotransmitter signaling is an early pathogenic mechanism associated with NFT formation in vulnerable nbM neurons and cognitive decline in AD, which may be amenable to therapeutic intervention early in the disease process.

Estimation of lifetime risks of Alzheimer's disease dementia using biomarkers for preclinical disease

INTRODUCTION

Lifetime risks are the probabilities of progressing to Alzheimer's disease (AD) dementia during one's lifespan. Here, we report the first estimates of the lifetime and ten-year risks of AD dementia based on age, gender, and biomarker tests for preclinical disease.

METHODS

We used a multistate model for the disease process together with US death rates.

RESULTS

Lifetime risks of AD dementia vary considerably by age, gender, and the preclinical or clinical disease state of the individual. For example, the lifetime risks for a female with only amyloidosis are 8.4% for a 90-year old and 29.3% for a 65-year old. Persons younger than 85 years with mild cognitive impairment, amyloidosis, and neurodegeneration have lifetime risks of AD dementia greater than 50%.

DISCUSSION

Most persons with preclinical AD will not develop AD dementia during their lifetimes. Lifetime risks help interpret the clinical significance of biomarker screening tests for AD.

Polygenic analysis of inflammatory disease variants and effects on microglia in the aging brain

BACKGROUND

The role of the innate immune system in Alzheimer's disease (AD) and neurodegenerative disease susceptibility has recently been highlighted in genetic studies. However, we do not know whether risk for inflammatory disease predisposes unaffected individuals to late-life cognitive deficits or AD-related neuropathology. We investigated whether genetic risk scores for seven immune diseases and central nervous system traits were related to cognitive decline (nmax = 1601), classical AD neuropathology (nmax = 985), or microglial density (nmax = 184).

METHODS

Longitudinal cognitive decline, postmortem amyloid and tau neuropathology, microglial density, and gene module expression from bulk brain tissue were all measured in participants from two large cohorts (the Rush Religious Orders Study and Memory and Aging Project; ROS/MAP) of elderly subjects (mean age at entry 78 +/- 8.7 years). We analyzed data primarily using robust regression methods. Neuropathologists were blind to clinical data.

RESULTS

The AD genetic risk scores, including and excluding APOE effects, were strongly associated with cognitive decline in all domains (min Puncor = 3.2 × 10- 29). Multiple sclerosis (MS), Parkinson's disease, and schizophrenia risk did not influence cognitive decline in older age, but the rheumatoid arthritis (RA) risk score alone was significantly associated with microglial density after correction (t146 = - 3.88, Puncor = 1.6 × 10- 4). Post-hoc tests found significant effects of the RA genetic risk score in multiple regions and stages of microglial activation (min Puncor = 1.5 × 10- 6). However, these associations were driven by only one or two variants, rather than cumulative polygenicity. Further, individual MS (Pone-sided < 8.4 × 10- 4) and RA (Pone-sided = 3 × 10- 4) variants associated with higher microglial density were also associated with increased expression of brain immune gene modules.

CONCLUSIONS

Our results demonstrate that global risk of inflammatory disease does not strongly influence aging-related cognitive decline but that susceptibility variants that influence peripheral immune function also alter microglial density and immune gene expression in the aging brain, opening a new perspective on the control of microglial and immune responses within the central nervous system. Further study on the molecular mechanisms of peripheral immune disease risk influencing glial cell activation will be required to identify key regulators of these pathways.

The associated volumes of sub-cortical structures and cognitive domain in patients of Mild Cognitive Impairment

This study aimed to explore the relationship between sub-cortical structures alterations and the cognitive domains in Mild Cognitive Impairment (MCI) patients, expected to find identifying sub-cortical structure markers of MCI progression to dementia. A total of 67 MCI patients (8 subjects refused to follow up) were recruited, who were divided into 21 stable MCI (sMCI) and 38 progress MCI (pMCI), according to cognitive assays. FreeSurfer software was used to perform volumetric measurements of the sub-cortical structures from 3.0 T magnetic resonance scans. Data revealed that pMCI subjects had lower scores in memory, language, executive and visual spatial compared with sMCI subjects. Compared with the sMCI group, the volume of the left thalamus, bilateral hippocampus, corpus callosum posterior and corpus callosum central was smaller in pMCI subjects. Partial correlation and general linear regression analysis showed that the left hippocampus was predicted region for memory, left thalamus was predicted region for language, executive and visual spatial. These current results suggest that the volumes of sub-cortical structures in stable MCI and progress MCI patients were heterogeneous. Among these regions, the left hippocampus was predicted region for memory, left thalamus was predicted region for language, executive and visual spatial, suggesting that these structures might be important for detecting the subtle effects of MCI patients' cognitive domain or to assess the effectiveness of therapeutic intervention for MCI.

White matter correlates of temporal discounting in older adults

Temporal discounting, the tendency to select a smaller reward offered sooner over a larger reward offered at a later time, has been associated with a number of real-world decision-making outcomes important for health and wellbeing. Neurobiological mechanisms supporting temporal discounting have been explored among younger participants, and these have considered white matter integrity. However, the white matter correlates of temporal discounting in older adults are unclear. We hypothesized that greater temporal discounting would be associated with poorer white matter integrity measures, more specifically lower fractional anisotropy and higher trace, in older adults. Participants were 302 older persons without dementia (mean age = 81.38, mean years of education = 15.75, 75.5% female, mean MMSE = 28.29) from the Rush Memory and Aging Project, a community-based longitudinal study of aging. Temporal discounting was assessed using standard elicitation questions. White matter integrity was assessed with diffusion tensor imaging (DTI). Regression models were adjusted for the effects of age, sex, education, and white matter lesions. Secondary models further adjusted for global cognition. Results revealed significant associations between temporal discounting and white matter integrity measures (FA and trace) in bilateral frontal, frontostriatal, and temporal-parietal lobe white matter tracts, and results remained significant after further accounting for global cognition. These results suggest that temporal discounting is inversely associated with white matter integrity in old age and that this association is independent of global cognition.

The Need for Innovative Methods to Increase Adherence in Individuals Experiencing Cognitive Decline

Cognitive impairment, particularly coupled with advanced age, is becoming an increasing concern for both clinicians and caregivers. Nonadherence is a common problem in individuals with cognitive impairment, leading to concerns regarding patient autonomy. The development and use of innovative strategies to overcome nonadherence is important to increase the likelihood of engagement in healthy lifestyle behaviors.

APOE ε2ε4 genotype, incident AD and MCI, cognitive decline, and AD pathology in older adults

OBJECTIVE

To examine the association of the APOE ε2ε4 genotype with incident Alzheimer disease (AD), mild cognitive impairment (MCI), cognitive decline, and AD pathology in older adults.

METHODS

We used data from 2,151 older adults of European ancestry who were free of dementia at baseline and underwent structured annual clinical evaluation in a longitudinal study for incident AD and MCI, and cognitive decline. Postmortem examination in decedents documented pathologic AD and quantified β-amyloid and neurofibrillary tangles. Participants were stratified into 4 groups based on APOE genotyping: ε2ε4, ε4 (ε4ε4, ε4ε3), ε2 (ε2ε2, ε2ε3), with ε3ε3 carriers serving as the reference group. We used Cox proportional hazards models to examine the association of APOE genotype with incident AD and MCI. Linear mixed-effect models were used to examine the association with cognitive decline. Logistic and linear regression models were used to examine AD pathology. All the models controlled for age, sex, and education.

RESULTS

Of the 2,151 participants included in this study, ε2ε4 accounted for 2.1%, ε3/4 and 4/4 21.8%, ε2/3 and 2/2 14.0%, and ε3ε3 62.1%. We did not observe a difference in the risk of AD for ε2ε4 compared to ε3ε3. In cases without cognitive impairment at baseline, ε2ε4 carriers had an increased risk of incident MCI (hazard ratio 2.13, 95% confidence interval 1.34-3.39, p = 0.002) and a faster rate of cognitive decline (estimate -0.047, SE 0.018, p = 0.008) compared to ε3ε3 carriers. In decedents (n = 1,100), ε2ε4 showed a 3-fold increased odds of pathologic AD and a higher β-amyloid load than ε3ε3.

CONCLUSION

APOE ε2ε4 genotype in older adults is associated with risk of MCI, cognitive decline, and a greater burden of AD pathology, especially β-amyloid.

Keep moving without hurting: The interaction between physical activity and pain in determining cognitive function at the population level

Background

A number of studies have evaluated the association between cognitive function, pain, and physical activity. To our knowledge, however, no previous studies have evaluated these factors at the population level.

Aims

To evaluate the association between cognitive function in the elderly with pain, physical activity, and the interaction between these variables. Estimates are generated for the United States population.

Methods

We made use of the NHANES database (1999–2002), making adjustments so that our results represent the United States population. Cognitive function was evaluated through the Digit Symbol Substitution Test. Our main predictors were (1) pain, defined as soreness of either the shoulder, neck, lower back and joint, or a severe headache (2) physical activity, measured as the performance while performing tasks at home, physical activity intensity, walking, bicycle riding, and muscle strengthening.

Results

Most individual pain sites were not significantly associated with cognitive function, while all physical activity factors were associated with an increase in cognitive function. When evaluating the sample subset of those with cognitive scores lower than the median, a combination of more pain and less physical activity was consistently associated with lower cognitive scores when compared to those performing more physical activity with or without pain. When evaluating individuals with cognitive scores above the median, a similar association pattern was perceived.

Conclusions

Among the population of individuals above the age of 60, higher cognitive levels are associated with more physical activity and less with pain, although both factors might impact cognition. Public policy resources should be commensurate with these findings when targeting cognitive function among the aging population.

Susceptibility to neurofibrillary tangles: role of the PTPRD locus and limited pleiotropy with other neuropathologies

Tauopathies, including Alzheimer's disease (AD) and other neurodegenerative conditions, are defined by a pathological hallmark: neurofibrillary tangles (NFTs). NFT accumulation is thought to be closely linked to cognitive decline in AD. Here, we perform a genome-wide association study for NFT pathologic burden and report the association of the PTPRD locus (rs560380, P=3.8 × 10^-8) in 909 prospective autopsies. The association is replicated in an independent data set of 369 autopsies. The association of PTPRD with NFT is not dependent on the accumulation of amyloid pathology. In contrast, we found that the ZCWPW1 AD susceptibility variant influences NFT accumulation and that this effect is mediated by an accumulation of amyloid β plaques. We also performed complementary analyses to identify common pathways that influence multiple neuropathologies that coexist with NFT and found suggestive evidence that certain loci may influence multiple different neuropathological traits, including tau, amyloid β plaques, vascular injury and Lewy bodies. Overall, these analyses offer an evaluation of genetic susceptibility to NFT, a common end point for multiple different pathologic processes.

The A/T/N biomarker scheme and patterns of brain atrophy assessed in mild cognitive impairment

The objective of this study was to evaluate the A/T/N biomarker scheme in relation with brain atrophy patterns in individuals with mild cognitive impairment (MCI). Of the 154 participants with MCI, 74 progressed to AD within 36-months, and 80 remained stable. In addition, 101 cognitively healthy participants and 102 participants with AD were included. The A/T/N classification was assessed with cerebrospinal fluid markers. Each individual was rated as either positive (abnormal) or negative (normal) on each biomarker. Brain atrophy was assessed with visual ratings from magnetic resonance imaging. None of the individuals with MCI progressed to AD if they had a negative "A" biomarker in conjunction with minimal atrophy. In contrary, several individuals with MCI progressed to AD if they had a positive "A" biomarker in conjunction with minimal atrophy. Numerous individuals with MCI showed inconsistency in the neurodegeneration domain ("N") regarding t-tau and atrophy. The assessment of the A/T/N classification scheme in addition with brain atrophy patterns in MCI, increases the knowledge of the clinical trajectories and the variability within the neurodegeneration domain. This emphasises that individuals with MCI display heterogeneous longitudinal patterns closely connected to their biomarker profiles, which could have important clinical implications.

Fractal regulation and incident Alzheimer's disease in elderly individuals

Introduction:

Healthy physiological systems exhibit fractal regulation (FR), generating similar fluctuation patterns in physiological outputs across different time scales. FR in motor activity is degraded in dementia, and the degradation correlates to cognitive decline. We tested whether degraded FR predicts Alzheimer’s dementia.

Methods:

FR in motor activity was assessed in 1097 nondemented older adults at baseline. Cognition was assessed annually for up to 11 years.

Results:

Participants with an FR metric at the 10th percentile in this cohort had a 1.8-fold Alzheimer’s disease risk (equivalent to the effect of being ~5.2 years older) and 1.3-fold risk for mild cognitive impairment (equivalent to the effect of being ~3.0 years older) than those at the 90th percentile. Consistently, degraded FR predicted faster cognitive decline. These associations were independent of physical activity, sleep fragmentation, and stability of daily activity rhythms.

Discussion:

FR may be a useful tool for predicting Alzheimer’s dementia.

Validity of the 8-Foot Up and Go, Timed Up and Go, and Activities-Specific Balance Confidence Scale in older adults with and without cognitive impairment

The purpose of this study was to determine whether (1) mild cognitive impairment (MCI) alters the validity of the Timed Up and Go (TUG), the 8-Foot Up and Go (8UG), or the Activities-Specific Balance Confidence (ABC) scale in the identification of fallers and nonfallers and (2) there were differences in the concurrent validity between the TUG and ABC when compared with the 8UG and ABC in those with and without MCI.. The classification of MCI was based on a score of <26 points on the Montreal Cognitive Assessment. For the 62 participants enrolled, excellent correlations were demonstrated in pairwise comparisons between the outcome measures (on a continuous scale). Based on frequently cited cutpoints, the sensitivity of the TUG was only 20% with a specificity of 94.6% and the sensitivity of the 8UG was 64% with a specificity of 75.7%. The TUG identified fallers at significantly different rates than the 8UG and the ABC (p < 0.05). For this reason, the 8UG is recommended as a more appropriate outcome measure for identifying fall risk in community-dwelling older adults. Fall history was found as the only significant predictor of test outcome for the TUG, 8UG, and ABC, indicating that MCI is not a significant determinant of test performance.

The Virtual Shop: A new immersive virtual reality environment and scenario for the assessment of everyday memory

BACKGROUND

Assessing and predicting memory performance in everyday life is a common assignment for neuropsychologists. However, most traditional neuropsychological tasks are not conceived to capture everyday memory performance.

NEW METHOD

The Virtual Shop is a fully immersive task developed to assess memory in a more ecological way than traditional neuropsychological assessments. Two studies were undertaken to assess the feasibility of the Virtual Shop and to appraise its ecological and construct validity. In study 1, 20 younger and 19 older adults completed the Virtual Shop task to evaluate its level of difficulty and the way the participants interacted with the VR material. The construct validity was examined with the contrasted-group method, by comparing the performance of younger and older adults. In study 2, 35 individuals with subjective cognitive decline completed the Virtual Shop task. Performance was correlated with an existing questionnaire evaluating everyday memory in order to appraise its ecological validity. To add further support to its construct validity, performance was correlated with traditional episodic memory and executive tasks.

RESULTS

All participants successfully completed the Virtual Shop. The task had an appropriate level of difficulty that helped differentiate younger and older adults, supporting the feasibility and construct validity of the task.

COMPARISON WITH EXISTING METHOD(S)

The performance on the Virtual Shop was significantly and moderately correlated with the performance on the questionnaire and on the traditional memory and executive tasks.

CONCLUSIONS

Results support the feasibility and both the ecological and construct validity of the Virtual Shop.

Cognitive impairment in Parkinson's disease, Alzheimer's dementia, and vascular dementia: the role of the clock-drawing test

AIM

Cognitive impairment is present in several neurodegenerative disorders. The clock-drawing test (CDT) represents a useful screening instrument for assessing the evolution of cognitive decline. The aim of this study was to investigate the sensitivity of the CDT in monitoring and differentiating the evolution of cognitive decline in Alzheimer's dementia (AD), vascular dementia (VaD), and Parkinson's disease (PD).

METHODS

This study involved 139 patients, including 39 patients with PD and mild cognitive impairment, 16 demented PD patients, 21 VaD patients with mild cognitive impairment, 17 patients with VaD, 33 patients with mild cognitive impairment due to AD, and 13 patients with probable AD. All participants completed the CDT. The Mini-Mental State Examination was administered to establish patients' cognitive functioning.

RESULTS

Comparisons of quantitative and qualitative CDT scores showed significant differences between the various diseases. Impairment of executive functioning seems to be more pronounced in PD and VaD than in AD. Patients with AD committed more errors related to a loss of semantic knowledge, indicating a severely reduced capacity in abstract and conceptual thinking.

CONCLUSION

Results support the usefulness and sensitivity of the CDT in the detection of different dementia subtypes. Qualitative error analysis of the CDT may be helpful in differentiating PD, VaD, and AD, even in the early stages of each disease.

Association of Cancer History with Alzheimer's Disease Dementia and Neuropathology

BACKGROUND

Cancer and Alzheimer's disease (AD) are common diseases of aging and share many risk factors. Surprisingly, however, epidemiologic data from several recent independent cohort studies suggest that there may be an inverse association between these diseases.

OBJECTIVE

To determine the relationship between history of cancer and odds of dementia proximate to death and neuropathological indices of AD.

METHODS

Using data from two separate clinical-pathologic cohort studies of aging and AD, the Religious Orders Study (ROS) and the Rush Memory and Aging Project (MAP), we compared odds of AD dementia proximate to death among participants with and without a history of cancer. We then examined the relation of history of cancer with measures of AD pathology at autopsy, i.e., paired helical filament tau (PHFtau) neurofibrillary tangles and amyloid-β load.

RESULTS

Participants reporting a history of cancer had significantly lower odds of AD (OR 0.70 [0.55-0.89], p = 0.0040) proximate to death as compared to participants reporting no prior history of cancer. The results remained significant after adjusting for multiple risk factors including age, sex, race, education, and presence of an APOEɛ4 allele. At autopsy, participants with a history of cancer had significantly fewer PHFtau tangles (p < 0.001) than participants without a history of cancer, but similar levels of amyloid-β.

CONCLUSIONS

Cancer survivors have reduced odds of developing AD and a lower burden of neurofibrillary tangle deposition.

Financial and Health Literacy Predict Incident Alzheimer's Disease Dementia and Pathology

BACKGROUND

Domain specific literacy is a multidimensional construct that requires multiple resources including cognitive and non-cognitive factors.

OBJECTIVE

We test the hypothesis that domain specific literacy is associated with Alzheimer's disease (AD) dementia and AD pathology after controlling for cognition.

METHODS

Participants were community-based older persons who completed a baseline literacy assessment, underwent annual clinical evaluations for up to 8 years, and agreed to organ donation after death. Financial and health literacy was measured using 32 questions and cognition was measured using 19 tests. Annual diagnosis of AD dementia followed standard criteria. AD pathology was examined postmortem by quantifying plaques and tangles. Cox models examined the association of literacy with incident AD dementia. Performance of model prediction for incident AD dementia was assessed using indices for integrated discrimination improvement and continuous net reclassification improvement. Linear regression models examined the independent association of literacy with AD pathology in autopsied participants.

RESULTS

All 805 participants were free of dementia at baseline and 102 (12.7%) developed AD dementia during the follow-up. Lower literacy was associated with higher risk for incident AD dementia (p < 0.001), and the association persisted after controlling for cognition (hazard ratio = 1.50, p = 0.004). The model including the literacy measure had better predictive performance than the one with demographics and cognition only. Lower literacy also was associated with higher burden of AD pathology after controlling for cognition (β= 0.07, p = 0.035).

CONCLUSION

Literacy predicts incident AD dementia and AD pathology in community-dwelling older persons, and the association is independent of traditional measures of cognition.

A 24-Week Multi-Modality Exercise Program Improves Executive Control in Older Adults with a Self-Reported Cognitive Complaint: Evidence from the Antisaccade Task

Exercise programs involving aerobic and resistance training (i.e., multiple-modality) have shown promise in improving cognition and executive control in older adults at risk, or experiencing, cognitive decline. It is, however, unclear whether cognitive training within a multiple-modality program elicits an additive benefit to executive/cognitive processes. This is an important question to resolve in order to identify optimal training programs that delay, or ameliorate, executive deficits in persons at risk for further cognitive decline. In the present study, individuals with a self-reported cognitive complaint (SCC) participated in a 24-week multiple-modality (i.e., the M2 group) exercise intervention program. In addition, a separate group of individuals with a SCC completed the same aerobic and resistance training as the M2 group but also completed a cognitive-based stepping task (i.e., multiple-modality, mind-motor intervention: M4 group). Notably, pre- and post-intervention executive control was examined via the antisaccade task (i.e., eye movement mirror-symmetrical to a target). Antisaccades are an ideal tool for the study of individuals with subtle executive deficits because of its hands- and language-free nature and because the task's neural mechanisms are linked to neuropathology in cognitive decline (i.e., prefrontal cortex). Results showed that M2 and M4 group antisaccade reaction times reliably decreased from pre- to post-intervention and the magnitude of the decrease was consistent across groups. Thus, multi-modality exercise training improved executive performance in persons with a SCC independent of mind-motor training. Accordingly, we propose that multiple-modality training provides a sufficient intervention to improve executive control in persons with a SCC.