Neuropsychological and neuroimaging changes in preclinical Alzheimer's disease

Cognition and Functional Capacity: An Initial Comparison of Veteran and Non-Veteran Older Adults

INTRODUCTION

The U.S. Military Veterans aged 65 and older comprise an estimated 43% of the 22 million living Veterans in the United States. Veterans have high rates of physical, psychiatric, and social challenges, but it is not known whether Veteran status confers additional risk for cognitive or functional impairments in later life. Thus, this investigation specifically compared older Veterans with their non-Veteran peers in cognitive functioning and performance-based functional capacity.

MATERIALS AND METHODS

Participants (N = 110; 29 Veterans and 81 non-Veterans) were part of a larger longitudinal study on biopsychosocial functioning in independently living older adult residents of a Continuing Care Senior Housing Community. The University of California San Diego Institutional Review Board approved the study and all participants provided written informed consent. Participants provided demographic and mental health information and were administered a comprehensive neuropsychological battery. Functional capacity was assessed using the UCSD Performance-Based Skills Assessment-Brief (UPSA-B), which uses financial and communication role-plays to assess everyday functioning skills. Neuropsychological scores were appropriately normed prior to analysis. Multivariate Analyses of Variances with post hoc t-tests and an Analysis of Covariance were used to examine neuropsychological and functional capacity differences, respectively, between Veterans and non-Veterans.

RESULTS

Veterans did not differ from non-Veterans in educational attainment (16.4 years versus 15.5 years, P = 0.110), but they were significantly older (mean age 86.9 years ± 5.7, versus 81.74 years ± 6.53; P < 0.001) and were more likely to be male (X2 [1, N = 110] = 62.39, P < 0.001). Thus, though neuropsychological norms already accounted for demographic differences in our participants, age and sex were controlled in the Analysis of Covariance predicting UPSA-B score from Veteran status. Results suggested that, compared to non-Veterans, Veterans had significantly worse performance in the list learning portion of a test of verbal memory (Hopkins Verbal Learning Test-Revised, Total Recall; t = 2.56, P = 0.012, d = 0.56). Veterans and non-Veterans did not significantly differ in performance on the delayed recall portion of the verbal learning test and did not differ on a cognitive screening test (Montreal Cognitive Assessment) or on measures of premorbid intellectual functioning (Wide Range Achievement Test-4 Reading), language (Boston Naming Test, Verbal Fluency), visual memory (Brief Visuospatial Memory Test-Revised), attention/working memory (WAIS-IV Digit Span), processing speed (WAIS-IV Digit Symbol Coding), executive function (Delis-Kaplan Executive Function System Trails and Color-Word Test), or functional capacity (UPSA-B). Because our examination of multiple outcomes might have inflated Type I error, we performed a post hoc adjustment of P values using Benjamini-Hochberg procedures and the group difference in verbal learning remained significant.

CONCLUSIONS

Despite largely similar function in most domains, Veterans performed significantly more poorly in verbal list learning than their non-Veteran peers. Additional attention should be given to the understanding, assessment, and possible treatment of learning and memory differences in older Veterans, as this may be an area in which Veteran status confers additional risk or vulnerability to decline. This is the first study to compare objective neuropsychological and functional performance between older (age 65+) US Veterans and non-Veterans.

BDNF Val66Met moderates episodic memory decline and tau biomarker increases in early sporadic Alzheimer's disease

OBJECTIVE

Allelic variation in the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism has been shown to moderate rates of cognitive decline in preclinical sporadic Alzheimer's disease (AD; i.e., Aβ + older adults), and pre-symptomatic autosomal dominant Alzheimer's disease (ADAD). In ADAD, Met66 was also associated with greater increases in CSF levels of total-tau (t-tau) and phosphorylated tau (p-tau181). This study sought to determine the extent to which BDNF Val66Met is associated with changes in episodic memory and CSF t-tau and p-tau181 in Aβ + older adults in early-stage sporadic AD.

METHOD

Aβ + Met66 carriers (n = 94) and Val66 homozygotes (n = 192) enrolled in the Alzheimer's Disease Neuroimaging Initiative who did not meet criteria for AD dementia, and with at least one follow-up neuropsychological and CSF assessment, were included. A series of linear mixed models were conducted to investigate changes in each outcome over an average of 2.8 years, covarying for CSF Aβ42, APOE ε4 status, sex, age, baseline diagnosis, and years of education.

RESULTS

Aβ + Met66 carriers demonstrated significantly faster memory decline (d = 0.33) and significantly greater increases in CSF t-tau (d = 0.30) and p-tau181 (d = 0.29) compared to Val66 homozygotes, despite showing equivalent changes in CSF Aβ42.

CONCLUSIONS

These findings suggest that reduced neurotrophic support, which is associated with Met66 carriage, may increase vulnerability to Aβ-related tau hyperphosphorylation, neuronal dysfunction, and cognitive decline even prior to the emergence of dementia. Additionally, these findings highlight the need for neuropsychological and clinicopathological models of AD to account for neurotrophic factors and the genes which moderate their expression.

Trajectories of cognitive decline in different domains prior to AD onset in persons with mild cognitive impairment

OBJECTIVES

To explore the trajectories and the change-points of global and five domain-specific cognitive functions before the onset of Alzheimer's disease (AD).

METHODS

Data was retrieved from the Alzheimer's Disease Neuroimaging Initiative with follow-up from 2005 to 2022. Participants with mild cognitive impairment (MCI) at baseline and those who progressed to AD during follow-up were included. The time of AD onset was defined as the visit time when participant was first diagnosed as AD during follow-up. Global and five domain-specific cognitive functions (immediate memory, visuospatial ability, language, processing speed and executive function) were assessed by Mini-Mental State Examination, Immediate recalling trials of Rey Auditory Verbal Learning Test, Clock Drawing Test, Animal Fluency Test, Part A and B of Trail Making Test, respectively. Their trajectories and change-points before AD onset were explored by generalized additive mixed models and piecewise linear regression models, respectively.

RESULTS

349 participants were diagnosed as MCI at baseline and converted to AD during follow-up, who were included in this study. They had been visited on an average of 4.6 times (SD = 2.1, range = 2.0-13.0), with a total of 1593 visits. Their mean baseline age and AD onset age were 74.4 (SD = 6.4, range = 60.0-88.4) and 77.0 (SD = 6.8, range = 60.5-94.7) years, respectively. Baseline age and educational year were significantly associated with global cognitive, immediate memory, language and executive function. Men presented better global cognitive function (β = 0.54, p < 0.05) but poorer immediate memory (β = -1.72, p < 0.05) than women. Immediate memory and visuospatial ability showed the earliest change-points at 4 years before the onset of AD (Note as T-4years), followed by language (T-3.5years), executive function (T-2.5 years), processing speed (T-2.0 years), and finally the global cognitive function (T-1.5years).

CONCLUSIONS

The trajectories of the six neuropsychological scores were non-linear and showed deterioration in functions over time. Immediate memory and visuospatial ability showed the earliest change-points prior to AD onset.

Cognitive trajectories preluding the onset of different dementia entities: a descriptive longitudinal study using the NACC database

OBJECTIVE

To describe the 10-year preclinical cognitive trajectories of older, non-demented individuals towards the onset of the four most prevalent types of dementia, i.e., Alzheimer's disease(AD), Lewy body(LBD), vascular(VD) and frontotemporal dementia(FTD).

METHODS

Our analysis focused on data from older (≥ 60years) NACC (National Alzheimer's Coordinating Center) participants. Four distinct presymptomatic dementia groups (AD-LBD-VD-FTD) and a comparison group of cognitively unimpaired(CU) participants were formed. Comprehensive cognitive assessments involving verbal episodic memory, semantic verbal fluency, confrontation naming, mental processing speed - attention and executive function - cognitive flexibility were conducted at baseline and on an approximately yearly basis. Descriptive analyses (adjusted general linear models) were performed to determine and compare the yearly cognitive scores of each group throughout the follow-up. Exploratory analyses were conducted to estimate the rates of cognitive decline.

RESULTS

There were 3343 participants who developed AD, 247 LBD, 108 FTD, 155 VD and 3398 composed the CU group. Participants with AD performed worse on episodic memory than those with VD and LBD for about 3 to 4 years prior to dementia onset (the FTD group documented an intermediate course). Presymptomatic verbal fluency and confrontation naming trajectories differentiated quite well between the FTD group and the remaining dementia entities. Participants with incident LBD and VD performed worse than those with AD on executive functions and mental processing speed-attention since about 5 years prior to the onset of dementia, and worse than those with FTD more proximally to the diagnosis of the disorder.

CONCLUSIONS

Heterogeneous cognitive trajectories characterize the presymptomatic courses of the most prevalent dementia entities.

Older adults at greater risk for Alzheimer's disease show stronger associations between sleep apnea severity in REM sleep and verbal memory

BACKGROUND

Obstructive sleep apnea (OSA) increases risk for cognitive decline and Alzheimer's disease (AD). While the underlying mechanisms remain unclear, hypoxemia during OSA has been implicated in cognitive impairment. OSA during rapid eye movement (REM) sleep is usually more severe than in non-rapid eye movement (NREM) sleep, but the relative effect of oxyhemoglobin desaturation during REM versus NREM sleep on memory is not completely characterized. Here, we examined the impact of OSA, as well as the moderating effects of AD risk factors, on verbal memory in a sample of middle-aged and older adults with heightened AD risk.

METHODS

Eighty-one adults (mean age:61.7 ± 6.0 years, 62% females, 32% apolipoprotein E ε4 allele (APOE4) carriers, and 70% with parental history of AD) underwent clinical polysomnography including assessment of OSA. OSA features were derived in total, NREM, and REM sleep. REM-NREM ratios of OSA features were also calculated. Verbal memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT). Multiple regression models evaluated the relationships between OSA features and RAVLT scores while adjusting for sex, age, time between assessments, education years, body mass index (BMI), and APOE4 status or parental history of AD. The significant main effects of OSA features on RAVLT performance and the moderating effects of AD risk factors (i.e., sex, age, APOE4 status, and parental history of AD) were examined.

RESULTS

Apnea-hypopnea index (AHI), respiratory disturbance index (RDI), and oxyhemoglobin desaturation index (ODI) during REM sleep were negatively associated with RAVLT total learning and long-delay recall. Further, greater REM-NREM ratios of AHI, RDI, and ODI (i.e., more events in REM than NREM) were related to worse total learning and recall. We found specifically that the negative association between REM ODI and total learning was driven by adults 60 + years old. In addition, the negative relationships between REM-NREM ODI ratio and total learning, and REM-NREM RDI ratio and long-delay recall were driven by APOE4 carriers.

CONCLUSION

Greater OSA severity, particularly during REM sleep, negatively affects verbal memory, especially for people with greater AD risk. These findings underscore the potential importance of proactive screening and treatment of REM OSA even if overall AHI appears low.

Disruption of the serial position effect as an early marker of Alzheimer's disease in Spanish-English bilinguals

OBJECTIVES

The present study examined if disruption of serial position effects in list recall could serve as an early marker of Alzheimer's disease (AD) in Spanish-English bilinguals.

METHODS

We tested 20 participants initially diagnosed as cognitively normal or with mild cognitive impairment who declined and eventually received a diagnosis of AD (decliners), and 37 who remained cognitively stable (controls) over at least 2 years. Participants were tested on the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word List Learning Test in English or Spanish as part of an annual neuropsychological evaluation.

RESULTS

Compared to controls, decliners exhibited significantly reduced recall including reduced primacy scores (i.e., items recalled from the first three list items on Trial 1), whereas recency scores (i.e., items recalled from the last 3 list items on Trial 1) were equivalent in decliners and controls. Further analyses suggested that the sensitivity of the primacy effect to preclinical AD was initially stronger in participants tested in Spanish, a surprising finding given that the CERAD was developed for English speakers. However, in the subsequent year of testing, primacy scores declined to the same level regardless of language of testing.

CONCLUSIONS

Several list learning measures may facilitate early diagnosis of AD in Spanish-English bilinguals, possibly including the relatively understudied primacy effect. Additional studies are needed to investigate the possibility that linguistic or demographic variables might modulate sensitivity of list learning tests to preclinical AD, which could lead to broader improvements in their utility for early diagnosis of AD in all populations.

The Efficiency of Attentional Networks in Takostubo Syndrome: A Study With the Attentional Network Task for Interaction

INTRODUCTION

The role of cardiovascular risk factors in the occurrence and progression of cognitive impairment is relevant in aging studies. In this condition, attention is one of the processes less studied, but preliminary evidence suggests an association between cardiometabolic alterations and attentional decline. Attention is not a unitary process but a set of independent systems (Alerting, Orienting, Executive), which can interact in certain conditions to ensure maximum behavioral efficiency.

METHODS

We investigated attentive networks and their interactions in patients with Takostubo syndrome (TTS). In all, 20 participants with TTS and 20 individuals without cardiovascular pathologies performed an Attention-Network Task for Interaction, which assesses attentional networks and their interactions.

RESULTS

Patients with TTS showed an atypical orienting effect when compared to the control group. Moreover, only the control group exhibited an interaction between orienting and alerting.

CONCLUSION

These findings establish the relevance of brain-heart interaction in identifying attentional impairment as a prodrome of progressively severe cognitive impairment in TTS.

Older adults at greater risk for Alzheimer's disease show stronger associations between sleep apnea severity and verbal memory

Background

Obstructive sleep apnea (OSA) increases risk for cognitive decline and Alzheimer's disease (AD). While the underlying mechanisms remain unclear, hypoxemia during OSA has been implicated in cognitive impairment. OSA during rapid eye movement (REM) sleep is usually more severe than in non-rapid eye movement (NREM) sleep, but the relative effect of oxyhemoglobin desaturation during REM versus NREM sleep on memory is not completely characterized. Here, we examined the impact of OSA, as well as the moderating effects of AD risk factors, on verbal memory in a sample of middle-aged and older adults with heightened AD risk.

Methods

Eighty-one adults (mean age:61.7±6.0 years, 62% females, 32% apolipoprotein E ε4 allele (APOE4) carriers, and 70% with parental history of AD) underwent clinical polysomnography including assessment of OSA. OSA features were derived in total, NREM, and REM sleep. REM-NREM ratios of OSA features were also calculated. Verbal memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT). Multiple regression models evaluated the relationships between OSA features and RAVLT scores while adjusting for sex, age, time between assessments, education years, body mass index (BMI), and APOE4 status or parental history of AD. The significant main effects of OSA features on RAVLT performance and the moderating effects of AD risk factors (i.e., sex, age, APOE4 status, and parental history of AD) were examined.

Results

Apnea-hypopnea index (AHI), respiratory disturbance index (RDI), and oxyhemoglobin desaturation index (ODI) during REM sleep were negatively associated with RAVLT total learning and long-delay recall. Further, greater REM-NREM ratios of AHI, RDI, and ODI (i.e., more events in REM than NREM) were related to worse total learning and recall. We found specifically that the negative association between REM ODI and total learning was driven by adults 60+ years old. In addition, the negative relationships between REM-NREM ODI ratio and total learning and REM-NREM RDI ratio and long-delay recall were driven by APOE4 carriers.

Conclusion

Greater OSA severity, particularly during REM sleep, negatively affects verbal memory, especially for people with greater AD risk. These findings underscore the potential importance of proactive screening and treatment of REM OSA even if overall AHI appears low.

Herpes simplex virus 2 serology is associated with thinner whole-brain cortex in community-dwelling older adults

Prior work in the Northern Manhattan Study (NOMAS) identified impaired cognition in cross-sectional analyses and more rapid memory decline in individuals with evidence of prior common infectious disease exposures. In this study, we sought to determine the cross-sectional relationship between prior exposure to cytomegalovirus, herpes simplex viruses 1 and 2, Chlamydia pneumoniae, and Helicobacter pylori and three magnetic resonance imaging (MRI) signatures (whole-brain cortical thickness, a previously validated AD signature, and hippocampal volume) in 455 NOMAS participants. We performed confounder-adjusted linear regression analyses between neuroimaging scores and both continuous serologies and categorical seropositivity of each pathogen, as well as a combined infectious burden index (IBI). We identified that increased serologic titers of herpes simplex virus 2 were associated with reduced whole-brain cortical thickness, and a combined score of HSV-2 and C. pneumoniae displayed an additive effect on reduced cortical thickness. Our findings suggest herpes simplex virus 2 seropositivity may contribute to accelerated brain aging, possibly resulting in an increased vulnerability to cognitive impairment and neurodegenerative disease in aging populations.

Neural network process simulations support a distributed memory system and aid design of a novel computer adaptive digital memory test for preclinical and prodromal Alzheimer's disease

OBJECTIVE

Growing evidence supports the importance of learning as a central deficit in preclinical/prodromal Alzheimer's disease. The aims of this study were to conduct a series of neural network simulations to develop a functional understanding of a distributed, nonmodular memory system that can learn efficiently without interference. This understanding is applied to the development of a novel digital memory test.

METHOD

Simulations using traditional feed forward neural network architectures to learn simple logic problems are presented. The simulations demonstrate three limitations: (a) inefficiency, (b) an inability to learn problems consistently, and (c) catastrophic interference when given multiple problems. A new mirrored cascaded architecture is introduced to address these limitations, with support provided by a series of simulations.

RESULTS

The mirrored cascaded architecture demonstrates efficient and consistent learning relative to feed forward networks but also suffers from catastrophic interference. Addition of context values to add the capability of distinguishing features as part of learning eliminates the problem of interference in the mirrored cascaded, but not the feed forward, architectures.

CONCLUSIONS

A mirrored cascaded architecture addresses the limitations of traditional feed forward neural networks, provides support for a distributed memory system, and emphasizes the importance of context to avoid interference. These process models contributed to the design of a digital computer-adaptive word list learning test that places maximum stress on the capability to distinguish specific episodes of learning. Process simulations provide a useful method of testing models of brain function and contribute to new approaches to neuropsychological assessment. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Diminished activation of excitatory neurons in the prelimbic cortex leads to impaired working memory capacity in mice

BACKGROUND

Working memory capacity impairment is an early sign of Alzheimer's disease, but the underlying mechanisms remain unclear. Clarifying how working memory capacity is affected will help us better understand the pathological mechanism of Alzheimer's disease. We used the olfactory working memory capacity paradigm to evaluate memory capacity in 3-month-old 5XFAD (an animal model of Alzheimer's disease) mice. Immunofluorescence staining of the prefrontal cortex was performed to detect the number of FOS-positive neurons, calmodulin-dependent protein kinase II-positive neurons, and glutamate decarboxylase-positive neurons in the prelimbic cortex and infralimbic cortex. A chemogenetic method was then used to modulate the inhibition and activation of excitatory neurons in the prelimbic cortex of wild-type and 5XFAD mice and to measure the memory capacity of mice.

RESULTS

Working memory capacity was significantly diminished in 5XFAD mice compared to littermate wild-type mice. Neuronal activation of the prelimbic cortex, but not the infralimbic cortex, was attenuated in 5XFAD mice performing the olfactory working memory capacity task. Subsequently, the FOS-positive neurons were co-localized with both calmodulin-dependent protein kinase II-positive neurons and glutamate decarboxylase-positive neurons. The results showed that the activation of excitatory neurons in the prelimbic cortex was correlated with working memory capacity in mice. Our results further demonstrate that the chemogenetic inhibition of prelimbic cortex excitatory neurons resulted in reduced working memory capacity in wild-type mice, while the chemogenetic activation of prelimbic cortex excitatory neurons improved the working memory capacity of 5XFAD mice.

CONCLUSION

The diminished activation of prelimbic cortex excitatory neurons in 5XFAD mice during task performance is associated with reduced working memory capacity, and activation modulation of excitatory neurons by chemogenetic methods can improve memory capacity impairment in 5XFAD mice. These findings may provide a new direction for exploring Alzheimer's disease therapeutic approaches.

Food Insecurity and Cognitive Trajectories in Community-Dwelling Medicare Beneficiaries 65 Years and Older

Importance

Food insecurity has a known association with prevalent impaired cognition. However, it is unknown whether food insecurity has a longitudinal association with cognitive decline among older adults.

Objective

To determine whether food insecurity is associated with a faster decline in cognitive function among community-dwelling older adults.

Design, Setting, and Participants

This retrospective cohort study used data from a nationally representative sample of Medicare beneficiaries 65 years and older recruited for the National Health and Aging Trends Study (NHATS). Community-dwelling NHATS participants were followed up for a maximum of 7 years (mean [SD] follow-up duration, 5.4 [1.1] years). Data were collected from January 1, 2012, to December 31, 2020, and analyzed from December 23, 2021, to December 6, 2022.

Exposures

Self-reported food insecurity assessed from 2012 to 2019.

Main Outcomes and Measures

Primary outcomes were immediate memory, delayed memory, and executive function collected from 2013 to 2020. Immediate and delayed recall were assessed by a 10-item word-list memory task (range, 0-10, with higher scores indicating more words recalled). Executive function was measured by the clock drawing test (range, 0-5, with higher scores indicating more accurate depiction of a clock). Each year's cognitive functions were linked to the prior year's food insecurity data. Linear mixed-effects models with random slopes and intercepts were used to examine the association between food insecurity and cognitive decline. Analytic weights in each year were applied to represent community-dwelling Medicare beneficiaries 65 years and older in 2011.

Results

Of 3037 participants, a weighted 57.8% (raw count, 1345) were younger than 75 years, 56.2% (raw count, 1777) were women, and most (84.9% [raw count, 2268]) were White. Over 7 years, 417 (weighted proportion, 12.1%) experienced food insecurity at least once. Food insecurity was associated with a faster decline in executive function in a fully adjusted model: the mean difference of annual change in executive function score between people exposed to and not exposed to food insecurity was -0.04 (95% CI, -0.09 to -0.003) points. However, food insecurity was not associated with changes in immediate and delayed memory (0.01 [95% CI, -0.05 to 0.08] and -0.01 [95% CI, -0.08 to 0.06], respectively).

Conclusions and Relevance

Among community-dwelling older adults, food insecurity was prevalent and associated with a decline in executive function. Interventions and policies aiming to increase healthy food access or reduce food insecurity should be assessed for their impact on older adults' cognitive outcome.

Cognitive trajectories preluding the imminent onset of Alzheimer's disease dementia in individuals with normal cognition: results from the HELIAD cohort

BACKGROUND

The cognitive trajectories of cognitively normal (CN) individuals rapidly progressing to Alzheimer's disease dementia (AD) have not been investigated.

AIM

To explore the preclinical pattern of cognitive performance heralding the rapid progression from normal cognition to AD.

METHODS

The HELIAD cohort underwent comprehensive neuropsychological assessments (memory, language, attention, executive and visuo-perceptual functions) at baseline and after approximately 3-year intervals. The cognitive trajectories of those with normal cognition at baseline were explored according to the follow-up diagnosis using adjusted generalised estimating equations analyses.

RESULTS

A total of 932 predominantly female (61%), older (72.9 ± 4.9), CN participants were followed for 3.09 (± 0.83) years. Among them, 761 individuals remained CN, 29 progressed to AD and 142 developed MCI (33 single-domain amnestic, 41 multidomain amnestic, 37 single-domain non-amnestic and 31 multidomain non-amnestic). Those progressing to AD were already performing worse than the healthy reference in every single cognitive domain at baseline. Cognitive deficits ranged between ~ 0.5SD (attention, executive function and language) and ~ 1.0SD (memory and visuo-perceptual skills). Throughout the 3-year follow-up, memory constantly exhibited the most prominent impairment compared to the remaining cognitive domains while executive function diminished in the most abrupt fashion (~ 0.19SD yearly) separating from the remaining three cognitive functions before the development of full-blown AD. Heterogeneous patterns of cognitive decline clearly differentiated those progressing to MCI from those rapidly converting to AD, as well.

DISCUSSION

Poor performance in every cognitive domain may characterise cognitively normal individuals at high risk of fast progression to AD.

CONCLUSION

Strict neuropsychological cut-offs fail to detect a considerable number of individuals at high risk of rapid progression to AD.

Assessing Longitudinal Cognitive Change in Mild Cognitive Impairment Using Estimated Standardized Regression-Based Formulas

BACKGROUND

Cognitive change in mild cognitive impairment (MCI), a likely prodrome to Alzheimer's disease, can be tracked with repeated neuropsychological assessments, but there has been little work quantifying these changes over time. Cognitive change can be statistically examined using standardized regression-based (SRB) formulas, which yield a z-score indicating amount of change compared to a normative group.

OBJECTIVE

To use SRB z-scores to quantify cognitive change in a sample of patients classified as MCI at baseline, and to compare cognitive change in those who remained MCI on follow-up (MCI-Stable) and those who progressed to dementia (MCI-Decline).

METHODS

Using 283 MCI patients from a cognitive disorders clinic who were re-assessed after approximately one- and one-half years, SRB z-scores were calculated for each test in a comprehensive neuropsychological battery for each participant.

RESULTS

There was a significant decline between timepoints across all cognitive tests, with the greatest amount of decline on tests of learning and memory. Group differences were seen on nearly all cognitive tests, with the MCI-Decline group showing more decline (i.e., significantly larger and negative z-scores) than the MCI-Stable participants. Notable cognitive decline was also observed in the MCI-Stable group, with z-scores ranging from -0.01 - -2.24 compared to normative data.

CONCLUSION

This study highlights the amount of cognitive decline that occurs in MCI, including for those who remain "stable" and those who progress to dementia. It also demonstrates the value of the SRB method in more clearly quantifying cognitive decline, which may help identify individuals most vulnerable to MCI progression.

Association between brain similarity to severe mental illnesses and comorbid cerebral, physical, and cognitive impairments

Severe mental illnesses (SMIs) are often associated with compromised brain health, physical comorbidities, and cognitive deficits, but it is incompletely understood whether these comorbidities are intrinsic to SMI pathophysiology or secondary to having SMIs. We tested the hypothesis that cerebral, cardiometabolic, and cognitive impairments commonly observed in SMIs can be observed in non-psychiatric individuals with SMI-like brain patterns of deviation as seen on magnetic resonance imaging. 22,883 participants free of common neuropsychiatric conditions from the UK Biobank (age = 63.4 ± 7.5 years, range = 45-82 years, 50.9% female) were split into discovery and replication samples. The regional vulnerability index (RVI) was used to quantify each participant's respective brain similarity to meta-analytical patterns of schizophrenia spectrum disorder, bipolar disorder, and major depressive disorder in gray matter thickness, subcortical gray matter volume, and white matter integrity. Cluster analysis revealed five clusters with distinct RVI profiles. Compared with a cluster with no RVI elevation, a cluster with RVI elevation across all SMIs and brain structures showed significantly higher volume of white matter hyperintensities (Cohen's d = 0.59, p_FDR < 10^-16), poorer cardiovascular (Cohen's d = 0.30, p_FDR < 10^-16) and metabolic (Cohen's d = 0.12, p_FDR = 1.3 × 10^-4) health, and slower speed of information processing (|Cohen's d| = 0.11-0.17, p_FDR = 1.6 × 10^-3-4.6 × 10^-8). This cluster also had significantly higher level of C-reactive protein and alcohol use (Cohen's d = 0.11 and 0.28, p_FDR = 4.1 × 10^-3 and 1.1 × 10^-11). Three other clusters with respective RVI elevation in gray matter thickness, subcortical gray matter volume, and white matter integrity showed intermediate level of white matter hyperintensities, cardiometabolic health, and alcohol use. Our results suggest that cerebral, physical, and cognitive impairments in SMIs may be partly intrinsic via shared pathophysiological pathways with SMI-related brain anatomical changes.

Increasing empathic concern relates to salience network hyperconnectivity in cognitively healthy older adults with elevated amyloid-β burden

Enhanced emotional empathy, the ability to share others' affective experiences, can be a feature of Alzheimer's disease (AD), but whether emotional empathy increases in the preclinical phase of the disease is unknown. We measured emotional empathy over time (range = 0 - 7.3 years, mean = 2.4 years) in 86 older adults during a period in which they were cognitively healthy, functionally normal, and free of dementia symptoms. For each participant, we computed longitudinal trajectories for empathic concern (i.e., an other-oriented form of emotional empathy that promotes prosocial actions) and emotional contagion (i.e., a self-focused form of emotional empathy often accompanied by feelings of distress) from informant ratings of participants' empathy on the Interpersonal Reactivity Index. Amyloid-β (Aβ) positron emission tomography (PET) scans were used to classify participants as either Aβ positive (Aβ+, n = 23) or negative (Aβ-, n = 63) based on Aβ-PET cortical binding. Participants also underwent structural and task-free functional magnetic resonance imaging approximately two years on average after their last empathy assessment, at which time most participants remained cognitively healthy. Results indicated that empathic concern, but not emotional contagion, increased more over time in Aβ+ participants than in Aβ- participants despite no initial group difference at the first measurement. Higher connectivity between certain salience network node-pairs (i.e., pregenual anterior cingulate cortex and periaqueductal gray) predicted longitudinal increases in empathic concern in the Aβ+ group but not in the Aβ- group. The Aβ+ participants also had higher overall salience network connectivity than Aβ- participants despite no differences in gray matter volume. These results suggest gains in empathic concern may be a very early feature of AD pathophysiology that relates to hyperconnectivity in the salience network, a system that supports emotion generation and interoception. A better understanding of emotional empathy trajectories in the early stages of AD pathophysiology will broaden the lens on preclinical AD changes and help clinicians to identify older adults who should be screened for AD biomarkers.

Normative data for the story recall subtest of the BEM-144 in the Quebec-French population aged 50 years and over

OBJECTIVE

The story recall subtest of the Batterie d'Efficience Mnésique (BEM-144) is a verbal episodic memory test that assesses immediate and episodic memory. Variables such as age, sex, and education level can impact performance on this type of memory test, as can cultural differences. Therefore, the purpose of this study was to establish normative data for the story recall subtest of the BEM-144 in the elderly French-Quebec population.

METHOD

The normative sample consisted of 260 healthy individuals aged 50-90 years, all from the province of Quebec, Canada. Analyses were performed to estimate the association between age, sex, and education level on one hand, and immediate and delayed recall performance, on the other hand.

RESULTS

The results show that all sociodemographic variables are significantly associated with story recall performance. Normative data are proposed in the form of regression equations.

CONCLUSIONS

Overall, these norms will be beneficial for the evaluation and detection of episodic memory impairment in middle-aged and older adults.

Voice biomarkers as indicators of cognitive changes in middle and later adulthood

Voice prosody measures have been linked with Alzheimer's disease (AD), but it is unclear whether they are associated with normal cognitive aging. We assessed relationships between voice measures and 10-year cognitive changes in the MIDUS national sample of middle-aged and older adults ages 42-92, with a mean age of 64.09 (standard deviation = 11.23) at the second wave. Seven cognitive tests were assessed in 2003-2004 (Wave 2) and 2013-2014 (Wave 3). Voice measures were collected at Wave 3 (N = 2585) from audio recordings of the cognitive interviews. Analyses controlled for age, education, depressive symptoms, and health. As predicted, higher jitter was associated with greater declines in episodic memory, verbal fluency, and attention switching. Lower pulse was related to greater decline in episodic memory, and fewer voice breaks were related to greater declines in episodic memory and verbal fluency, although the direction of these effects was contrary to hypotheses. Findings suggest that voice biomarkers may offer a promising approach for early detection of risk factors for cognitive impairment or AD.

Neuroimaging Markers for Determining Former American Football Players at Risk for Alzheimer's Disease

NFL players, by virtue of their exposure to traumatic brain injury (TBI), are at higher risk of developing dementia and Alzheimer's disease (AD) than the general population. Early recognition and intervention before the onset of clinical symptoms could potentially avert/delay the long-term consequences of these diseases. Given that AD is thought to have a long pre-clinical incubation period, the aim of the current research was to determine whether former NFL players show evidence of incipient dementia in their structural imaging before diagnosis of AD. To identify neuroimaging markers of AD, against which former NFL players would be compared, we conducted a whole-brain volumetric analysis using a cohort of AD patients (ADNI clinical database) to produce a set of brain regions demonstrating sensitivity to early AD pathology (i.e., the “AD fingerprint”). A group of 46 former NFL players' brain magnetic resonance images were then interrogated using the AD fingerprint, that is, the former NFL subjects were compared volumetrically to AD patients using a T1-weighted magnetization-prepared rapid gradient echo sequence. The FreeSurfer image analysis suite (version 6.0) was used to obtain volumetric and cortical thickness data. The Automated Neuropsychological Assessment Metric-Version 4 was used to assess current cognitive functioning. A total of 55 brain regions demonstrated significant atrophy or ex vacuo dilatation bilaterally in AD patients versus controls. Of the 46 former NFL players, 41% demonstrated a greater than expected number of atrophied/dilated AD regions compared with age-matched controls, presumably reflecting AD pathology.

Adolescent Binge Alcohol Enhances Early Alzheimer's Disease Pathology in Adulthood Through Proinflammatory Neuroimmune Activation

Epidemiological studies suggest that heavy alcohol use early in life is associated with increased risk for Alzheimer's disease (AD). However, mechanisms connecting AD with alcohol use have not been identified. Both heavy alcohol use and AD feature increased proinflammatory signaling. Therefore, we hypothesized that adolescent binge ethanol would increase AD molecular and behavioral pathology in adulthood through proinflammatory signaling. The 3xTg-AD mouse model (APPSwe, tauP301, Psen1^tm1Mpm) which features amyloid (Aβ) and tau pathology beginning at 6-12 months underwent adolescent intermittent ethanol (AIE, 5 g/kg/d, i.g., P25-55) with assessment of AD pathologic mediators at P200. A second group of mice received AIE +/- minocycline (30 mg/kg/d, IP) followed by behavioral testing in adulthood. Behavioral testing and age of testing included: locomotor activity and exploration (27-28 weeks), novel object recognition (NORT, 28-30 weeks), 3-chamber sociability and social memory (29-31 weeks), prepulse inhibition (PPI, 30-32 weeks), Morris Water Maze with reversal (MWM, 31-35 weeks), and Piezo sleep monitoring (35-37 weeks). We found that AIE increased levels of neurotoxic Aβ_1-42 in adult female hippocampus as well as intraneuronal Aβ_1-42 in amygdala and entorhinal cortex. Phosphorylated tau at residue Thr181 (p-tau-181) was also increased in female hippocampus by AIE. Several proinflammatory genes were persistently increased by AIE in the female hippocampus, including IL-1β, MCP-1, IL-6, and IFNα. Expression of these genes was strongly correlated with the levels of Aβ_1-42 and p-tau-181 in hippocampus. AIE caused persistent decreases in locomotor activity (open-field and NORT habituation) and increased anxiety-like behavior (thigmotaxis) while reducing memory retention. Treatment with the anti-inflammatory compound minocycline during AIE blocked persistent increases in Aβ_1-42 in amygdala and p-tau-181 in hippocampus, and prevented AIE-induced thigmotaxis and memory loss. Together, these data find that adolescent binge ethanol enhances AD molecular and behavioral pathology in adulthood through proinflammatory signaling. Blockade of proinflammatory signaling during ethanol exposure prevents ethanol-induced effects on pathologic accumulation of AD-associated proteins and persistent behavior changes relevant to human AD.

Beta-amyloid moderates the relationship between cortical thickness and attentional control in middle- and older-aged adults

Although often unmeasured in studies of cognition, many older adults possess Alzheimer disease (AD) pathologies such as beta-amyloid (Aβ) deposition, despite being asymptomatic. We were interested in examining whether the behavior-structure relationship observed in later life was altered by the presence of preclinical AD pathology. A total of 511 cognitively unimpaired adults completed magnetic resonance imaging and three attentional control tasks; a subset (n = 396) also underwent Aβ-positron emissions tomography. A vertex-wise model was conducted to spatially represent the relationship between cortical thickness and average attentional control accuracy, while moderation analysis examined whether Aβ deposition impacted this relationship. First, we found that reduced cortical thickness in temporal, medial- and lateral-parietal, and dorsolateral prefrontal cortex, predicted worse performance on the attention task composite. Subsequent moderation analyses observed that levels of Aβ significantly influence the relationship between cortical thickness and attentional control. Our results support the hypothesis that preclinical AD, as measured by Aβ deposition, is partially driving what would otherwise be considered general aging in a cognitively normal adult population.

Neurodegenerative Disorders of Alzheimer, Parkinsonism, Amyotrophic Lateral Sclerosis and Multiple Sclerosis: An Early Diagnostic Approach for Precision Treatment

Neurodegenerative diseases (NDs) are characterised by progressive dysfunction of synapses, neurons, glial cells and their networks. Neurodegenerative diseases can be classified according to primary clinical features (e.g., dementia, parkinsonism, or motor neuron disease), anatomic distribution of neurodegeneration (e.g., frontotemporal degenerations, extrapyramidal disorders, or spinocerebellar degenerations), or principal molecular abnormalities. The most common neurodegenerative disorders are amyloidosis, tauopathies, a-synucleinopathy, and TAR DNA-binding protein 43 (TDP-43) proteopathy. The protein abnormalities in these disorders have abnormal conformational properties along with altered cellular mechanisms, and they exhibit motor deficit, mitochondrial malfunction, dysfunctions in autophagic-lysosomal pathways, synaptic toxicity, and more emerging mechanisms such as the roles of stress granule pathways and liquid-phase transitions. Finally, for each ND, microglial cells have been reported to be implicated in neurodegeneration, in particular, because the microglial responses can shift from neuroprotective to a deleterious role. Growing experimental evidence suggests that abnormal protein conformers act as seed material for oligomerization, spreading from cell to cell through anatomically connected neuronal pathways, which may in part explain the specific anatomical patterns observed in brain autopsy sample. In this review, we mention the human pathology of select neurodegenerative disorders, focusing on how neurodegenerative disorders (i.e., Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis) represent a great healthcare problem worldwide and are becoming prevalent because of the increasing aged population. Despite many studies have focused on their etiopathology, the exact cause of these diseases is still largely unknown and until now with the only available option of symptomatic treatments. In this review, we aim to report the systematic and clinically correlated potential biomarker candidates. Although future studies are necessary for their use in early detection and progression in humans affected by NDs, the promising results obtained by several groups leads us to this idea that biomarkers could be used to design a potential therapeutic approach and preclinical clinical trials for the treatments of NDs.

Rates of Cognitive and Functional Impairments in Older Adults Residing in a Continuing Care Senior Housing Community

OBJECTIVE

The current cross-sectional study examined cognition and performance-based functional abilities in a continuing care senior housing community (CCSHC) that is comparable to other CCSHCs in the US with respect to residents' demographic characteristics.

METHOD

Participants were 110 older adult residents of the independent living unit. We assessed sociodemographics, mental health, neurocognitive functioning, and functional capacity.

RESULTS

Compared to normative samples, participants performed at or above expectations in terms of premorbid functioning, attention span and working memory, processing speed, timed set-shifting, inhibitory control, and confrontation naming. They performed below expectation in verbal fluency and verbal and visual learning and memory, with impairment rates [31.4% (>1 SD below the mean) and 18.49% (>1.5 SD below the mean)] well above the general population (16% and 7%, respectively). Within the cognitive test battery, two tests of delayed memory were most predictive of a global deficit score. Most cognitive test scores correlated with performance-based functional capacity.

CONCLUSIONS

Overall, results suggest that a subset of older adults in the independent living sector of CCSHCs are cognitively and functionally impaired and are at risk for future dementia. Results also argue for the inclusion of memory tests in abbreviated screening batteries in this population. We suggest that CCSHCs implement regular cognitive screening procedures to identify and triage those older adults who could benefit from interventions and, potentially, a transition to a higher level of care.

Association of low-frequency and rare coding variants with information processing speed

Measures of information processing speed vary between individuals and decline with age. Studies of aging twins suggest heritability may be as high as 67%. The Illumina HumanExome Bead Chip genotyping array was used to examine the association of rare coding variants with performance on the Digit-Symbol Substitution Test (DSST) in community-dwelling adults participating in the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. DSST scores were available for 30,576 individuals of European ancestry from nine cohorts and for 5758 individuals of African ancestry from four cohorts who were older than 45 years and free of dementia and clinical stroke. Linear regression models adjusted for age and gender were used for analysis of single genetic variants, and the T5, T1, and T01 burden tests that aggregate the number of rare alleles by gene were also applied. Secondary analyses included further adjustment for education. Meta-analyses to combine cohort-specific results were carried out separately for each ancestry group. Variants in RNF19A reached the threshold for statistical significance (p = 2.01 × 10^-6) using the T01 test in individuals of European descent. RNF19A belongs to the class of E3 ubiquitin ligases that confer substrate specificity when proteins are ubiquitinated and targeted for degradation through the 26S proteasome. Variants in SLC22A7 and OR51A7 were suggestively associated with DSST scores after adjustment for education for African-American participants and in the European cohorts, respectively. Further functional characterization of its substrates will be required to confirm the role of RNF19A in cognitive function.

Interindividual and intraindividual variability in amnestic mild cognitive impairment (aMCI) measured with an online cognitive assessment

INTRODUCTION

Mean cognitive performance is worse in amnestic mild cognitive impairment (aMCI) compared to control groups. However, studies on variability of cognitive performance in aMCI have yielded inconclusive results, with many differences in variability measures and samples from one study to another.

METHODS

We examined variability in aMCI using an existing older adult sample (n = 91; 51 with aMCI, 40 with normal cognition for age), measured with an online self-administered computerized cognitive assessment (Cogniciti's Brain Health Assessment). Our methodology extended past findings by using pure measures of variability (controlling for confounding effects of group performance or practice), and a clinically representative aMCI sample (reflecting the continuum of cognitive performance between normal cognition and aMCI).

RESULTS

Between-group t-tests showed significantly greater between-person variability (interindividual variability or diversity) in overall cognitive performance in aMCI than controls, although the effect size was with a small to moderate effect size, d = 0.44. No significant group differences were found in within-person variability (intraindividual variability) across cognitive tasks (dispersion) or across trials of a response time task (inconsistency), which may be because we used a sample measuring the continuum of cognitive performance. Exploratory correlation analyses showed that a worse overall score was associated with greater inter- and intraindividual variability, and that variability measures were correlated with each other, indicating people with worse cognitive performance were more variable.

DISCUSSION

The current study demonstrates that self-administered online tests can be used to remotely assess different types of variability in people at risk of Alzheimer`s. Our findings show small but significantly more interindividual differences in people with aMCI. This diversity is considered as "noise" in standard assessments of mean performance, but offers an interesting and cognitively informative "signal" in itself.

Is comprehensiveness critical? Comparing short and long format cognitive assessments in preclinical Alzheimer disease

BACKGROUND

Comprehensive testing of cognitive functioning is standard practice in studies of Alzheimer disease (AD). Short-form tests like the Montreal Cognitive Assessment (MoCA) use a "sampling" of measures, administering key items in a shortened format to efficiently assess cognition while reducing time requirements, participant burden, and administrative costs. We compared the MoCA to a commonly used long-form cognitive battery in predicting AD symptom onset and sensitivity to AD neuroimaging biomarkers.

METHODS

Survival, area under the receiver operating characteristic (ROC) curve (AUC), and multiple regression analyses compared the MoCA and long-form measures in predicting time to symptom onset in cognitively normal older adults (n = 6230) from the National Alzheimer's Coordinating Center (NACC) cohort who had, on average, 2.3 ± 1.2 annual assessments. Multiple regression models in a separate sample (n = 416) from the Charles F. and Joanne Knight Alzheimer Disease Research Center (Knight ADRC) compared the sensitivity of the MoCA and long-form measures to neuroimaging biomarkers including amyloid PET, tau PET, and cortical thickness.

RESULTS

Hazard ratios suggested that both the MoCA and the long-form measures are similarly and modestly efficacious in predicting symptomatic conversion, although model comparison analyses indicated that the long-form measures slightly outperformed the MoCA (HRs > 1.57). AUC analyses indicated no difference between the measures in predicting conversion (DeLong's test, Z = 1.48, p = 0.13). Sensitivity to AD neuroimaging biomarkers was similar for the two measures though there were only modest associations with tau PET (rs = - 0.13, ps < 0.02) and cortical thickness in cognitively normal participants (rs = 0.15-0.16, ps < 0.007).

CONCLUSIONS

Both test formats showed weak associations with symptom onset, AUC analyses indicated low diagnostic accuracy, and biomarker correlations were modest in cognitively normal participants. Alternative assessment approaches are needed to improve how clinicians and researchers monitor cognitive changes and disease progression prior to symptom onset.

Impact of Cardiovascular Risk Factors in Adolescence, Young Adulthood, and Midlife on Late-Life Cognition: Study of Healthy Aging in African Americans

BACKGROUND

Midlife cardiovascular risk factors (CVRFs) increase risk of dementia. Black Americans experience an elevated prevalence of CVRFs and dementia. However, little is known of how CVRFs prior to midlife affect late-life cognition. We examined CVRFs in adolescence, young adulthood, and midlife with late-life cognition in the Study of Healthy Aging in African Americans (STAR).

METHOD

STAR assesses cognitive aging among 764 Black Americans aged ≥50 (mean age = 69; SD = 9; range = 53-95). Participants' body mass index, blood pressure, glucose, and total cholesterol were collected during Multiphasic Health Checkups (MHC; 1964-1985). At STAR baseline (2018-2019), executive function, verbal episodic memory, and semantic memory were measured using the Spanish and English Neuropsychological Assessment Scales. Linear regression models examined associations between CVRFs and cognition adjusting for demographics and years since MHC.

RESULTS

At MHC, 36% of participants had 1 CVRF and 26% had ≥2. Twenty-two percent of participants were adolescents (age 12-20), 62% young adults (age 21-34), and 16% midlife adults (age 35-56). Overweight/obesity was not associated with cognition. Hypertension was associated with worse executive function (β [95% CI]: -0.14 [-0.28, -0.0003]) and verbal episodic memory (β [95% CI]: -0.22 [-0.37, -0.07]) compared to normotension. Diabetes was associated with worse executive function (β [95% CI]: -0.43 [-0.83, -0.03]). Having ≥2 CVRFs (vs 0) was associated with worse executive function (β [95% CI]: -0.19 [-0.34, -0.03]) and verbal episodic memory (β [95% CI]: -0.25 [-0.41, -0.08]). Adolescents with hypertension had lower late-life executive function compared to normotensive adolescents (β [95% CI]: -0.39 [-0.67, -0.11]). Young adulthood hypertension (β [95% CI]: -0.29 [-0.49, -0.09]) and midlife hyperlipidemia (β [95% CI]: -0.386 [-0.70, -0.02]) were associated with lower verbal episodic memory.

CONCLUSIONS

Among Black Americans, life-course CVRFs were associated with poorer executive function and verbal episodic memory emphasizing the importance of cardiovascular health on the aging brain.

Event-Related Potentials, Inhibition, and Risk for Alzheimer's Disease Among Cognitively Intact Elders

BACKGROUND

Despite advances in understanding Alzheimer's disease (AD), prediction of AD prior to symptom onset remains severely limited, even when primary risk factors such as the apolipoprotein E (APOE) ɛ4 allele are known.

OBJECTIVE

Although executive dysfunction is highly prevalent and is a primary contributor to loss of independence in those with AD, few studies have examined neural differences underlying executive functioning as indicators of risk for AD prior to symptom onset, when intervention might be effective.

METHODS

This study examined event-related potential (ERP) differences during inhibitory control in 44 cognitively intact older adults (20 ɛ4+, 24 ɛ4-), relative to 41 young adults. All participants completed go/no-go and stop-signal tasks.

RESULTS

Overall, both older adult groups exhibited slower reaction times and longer ERP latencies compared to young adults. Older adults also had generally smaller N200 and P300 amplitudes, except at frontal electrodes and for N200 stop-signal amplitudes, which were larger in older adults. Considered with intact task accuracy, these findings suggest age-related neural compensation. Although ɛ4 did not distinguish elders during go or no-go tasks, this study uniquely showed that the more demanding stop-signal task was sensitive to ɛ4 differences, despite comparable task and neuropsychological performance with non-carriers. Specifically, ɛ4+ elders had slower frontal N200 latency and larger N200 amplitude, which was most robust at frontal sites, compared with ɛ4-.

CONCLUSION

N200 during a stop-signal task is sensitive to AD risk, prior to any evidence of cognitive dysfunction, suggesting that stop-signal ERPs may be an important protocol addition to neuropsychological testing.

Trajectories of decline on instrumental activities of daily living prior to dementia in persons with mild cognitive impairment

OBJECTIVES

The main objective was to determine the trajectory of instrumental activities of daily living (iADL) decline in persons with mild cognitive impairment (MCI) who progressed towards dementia relative to persons with MCI who remained stable.

METHODS/DESIGN

At study entry, 121 participants met criteria for MCI. Based on the follow-up, 47 participants later converted to dementia and were identified as progressors. Sixteen participants, identified as decliners, presented a significant cognitive decline but did not reach the criteria for dementia within the study timeframe. Stable MCI remained cognitively stable during the 5-year follow-up; n = 58. Participants completed a yearly assessment using clinical tests/questionnaires, neuropsychological measures, and functional autonomy assessment until they met criteria for dementia. The average number of months for the follow-up was 34.

RESULTS

Many years of stable performance followed by an accelerated decline just prior to diagnosis, was observed for complex activities for progressors. No change was found for stable MCI and a gradual linear decline characterized decliners. The housekeeping-related activities component showed a linear decline in progressors and did not change in stable and decliner MCI. We found a predictive model that includes significant predictors of dementia conversion with a high diagnostic accuracy the following year (area under the curve = 0.94 [95% confidence level; lower bound: 0.87, upper bound: 1]).

CONCLUSIONS

It is critical to assess iADL that reflect complex activities in the evaluation of MCI individuals as their impairment, combined with change on cognitive markers, indicates a higher risk of dementia progression 1 or 2 years later.

A White Matter Connection of Schizophrenia and Alzheimer's Disease

Schizophrenia (SZ) is a severe psychiatric illness associated with an elevated risk for developing Alzheimer's disease (AD). Both SZ and AD have white matter abnormalities and cognitive deficits as core disease features. We hypothesized that aging in SZ patients may be associated with the development of cerebral white matter deficit patterns similar to those observed in AD. We identified and replicated aging-related increases in the similarity between white matter deficit patterns in patients with SZ and AD. The white matter "regional vulnerability index" (RVI) for AD was significantly higher in SZ patients compared with healthy controls in both the independent discovery (Cohen's d = 0.44, P = 1·10-5, N = 173 patients/230 control) and replication (Cohen's d = 0.78, P = 9·10-7, N = 122 patients/64 controls) samples. The degree of overlap with the AD deficit pattern was significantly correlated with age in patients (r = .21 and .29, P < .01 in discovery and replication cohorts, respectively) but not in controls. Elevated RVI-AD was significantly associated with cognitive measures in both SZ and AD. Disease and cognitive specificities were also tested in patients with mild cognitive impairment and showed intermediate overlap. SZ and AD have diverse etiologies and clinical courses; our findings suggest that white matter deficits may represent a key intersecting point for these 2 otherwise distinct diseases. Identifying mechanisms underlying this white matter deficit pattern may yield preventative and treatment targets for cognitive deficits in both SZ and AD patients.

Preventing dementia? Interventional approaches in mild cognitive impairment

Mild cognitive impairment (MCI) is defined as an intermediate state between normal cognitive aging and dementia. It describes a status of the subjective impression of cognitive decline and objectively detectible memory impairment beyond normal age-related changes. Activities of daily living are not affected. As the population ages, there is a growing need for early, proactive programs that can delay the consequences of dementia and improve the well-being of people with MCI and their caregivers. Various forms and approaches of intervention for older people with MCI have been suggested to delay cognitive decline. Pharmacological as well as non-pharmacological approaches (cognitive, physiological, nutritional supplementation, electric stimulation, psychosocial therapeutic) and multicomponent interventions have been proposed. Interventional approaches in MCI from 2009 to April 2019 concerning the cognitive performance are presented in this review.

Reaction time and response inhibition in autosomal dominant Alzheimer's disease

OBJECTIVE

Subtle deficits in several cognitive domains characterize the neuropsychological profile of preclinical Alzheimer's disease (AD). Assessment of preclinical individuals with genes causing autosomal dominant AD (ADAD) provides a model for prodromal disease. We sought to sensitively evaluate attention and working memory using a computerized battery in non-demented persons carrying ADAD mutations.

METHOD

A total of 71 non-demented Latinos at-risk for ADAD mutations were recruited [40 mutation carriers (MCs), 31 non-mutation carriers (NCs)] and completed a Spanish language chronometric battery of speeded decision and working memory tasks.

RESULTS

On two complex reaction time (RT) tasks involving decision-making and response inhibition, MCs exhibited slower RTs than NCs as they approached their anticipated age of dementia diagnosis. Education moderated these effects, but only in younger MCs. APOE ε4 status was not associated with age-related slowing among NCs or MCs on any of the tests.

CONCLUSIONS

Our findings indicate MCs respond more slowly as they approach the age of dementia onset on tasks with greater demands on executive function. Our results also suggest these effects were not explained by APOE ε4 status independently of ADAD mutation status. Computerized reaction time tests can provide sensitive measures of the earliest cognitive changes in AD.

The Application of Artificial Intelligence in the Genetic Study of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disease in which genetic factors contribute approximately 70% of etiological effects. Studies have found many significant genetic and environmental factors, but the pathogenesis of AD is still unclear. With the application of microarray and next-generation sequencing technologies, research using genetic data has shown explosive growth. In addition to conventional statistical methods for the processing of these data, artificial intelligence (AI) technology shows obvious advantages in analyzing such complex projects. This article first briefly reviews the application of AI technology in medicine and the current status of genetic research in AD. Then, a comprehensive review is focused on the application of AI in the genetic research of AD, including the diagnosis and prognosis of AD based on genetic data, the analysis of genetic variation, gene expression profile, gene-gene interaction in AD, and genetic analysis of AD based on a knowledge base. Although many studies have yielded some meaningful results, they are still in a preliminary stage. The main shortcomings include the limitations of the databases, failing to take advantage of AI to conduct a systematic biology analysis of multilevel databases, and lack of a theoretical framework for the analysis results. Finally, we outlook the direction of future development. It is crucial to develop high quality, comprehensive, large sample size, data sharing resources; a multi-level system biology AI analysis strategy is one of the development directions, and computational creativity may play a role in theory model building, verification, and designing new intervention protocols for AD.

Midlife Insulin Resistance as a Predictor for Late-Life Cognitive Function and Cerebrovascular Lesions

Background:

Type 2 diabetes (T2DM) increases the risk for Alzheimer’s disease (AD) but not for AD neuropathology. The association between T2DM and AD is assumed to be mediated through vascular mechanisms. However, insulin resistance (IR), the hallmark of T2DM, has been shown to associate with AD neuropathology and cognitive decline.

Objective:

To evaluate if midlife IR predicts late-life cognitive performance and cerebrovascular lesions (white matter hyperintensities and total vascular burden), and whether cerebrovascular lesions and brain amyloid load are associated with cognitive functioning.

Methods:

This exposure-to-control follow-up study examined 60 volunteers without dementia (mean age 70.9 years) with neurocognitive testing, brain 3T-MRI and amyloid-PET imaging. The volunteers were recruited from the Finnish Health 2000 survey (n = 6062) to attend follow-up examinations in 2014–2016 according to their insulin sensitivity in 2000 and their APOE genotype. The exposure group (n = 30) had IR in 2000 and the 30 controls had normal insulin sensitivity. There were 15 APOEɛ4 carriers per group. Statistical analyses were performed with multivariable linear models.

Results:

At follow-up the IR+group performed worse on executive functions (p = 0.02) and processing speed (p = 0.007) than the IR- group. The groups did not differ in cerebrovascular lesions. No associations were found between cerebrovascular lesions and neurocognitive test scores. Brain amyloid deposition associated with slower processing speed.

Conclusion:

Midlife IR predicted poorer executive functions and slower processing speed, but not cerebrovascular lesions. Brain amyloid deposition was associated with slower processing speed. The association between midlife IR and late-life cognition might not be mediated through cerebrovascular lesions measured here.

A systematic review of cognitive event-related potentials in mild cognitive impairment and Alzheimer's disease

This systematic review examined whether event-related potentials (ERPs) during higher cognitive processing can detect subtle, early signs of neurodegenerative disease. Original, empirical studies retrieved from PsycINFO and PubMed were reviewed if they analyzed patterns in cognitive ERPs (≥150 ms post-stimulus) differentiating mild cognitive impairment (MCI), Alzheimer's disease (AD), or cognitively intact elders who carry AD risk through the Apolipoprotein-E ε4 allele (ε4+) from healthy older adult controls (HC). The 100 studies meeting inclusion criteria (MCI = 47; AD = 47; ε4+ = 6) analyzed N200, P300, N400, and occasionally, later components. While there was variability across studies, patterns of reduced amplitude and delayed latency were apparent in pathological aging, consistent with AD-related brain atrophy and cognitive impairment. These effects were particularly evident in advanced disease progression (i.e., AD > MCI) and in later ERP components measured during complex tasks. Although ERP studies in intact ε4+ elders are thus far scarce, a similar pattern of delayed latency was notable, along with a contrasting pattern of increased amplitude, consistent with compensatory neural activation. This limited work suggests ERPs might be able to index early neural changes indicative of future cognitive decline in otherwise healthy elders. As ERPs are also accessible and affordable relative to other neuroimaging methods, their addition to cognitive assessment might substantively enhance early identification and characterization of neural dysfunction, allowing opportunity for earlier differential diagnosis and targeting of intervention. To evaluate this possibility there is urgent need for well-powered studies assessing late cognitive ERPs during complex tasks, particularly in healthy elders at risk for cognitive decline.

Informatics and Cognitive Assessment: A RUDAS Scale Paradigm

BACKGROUND

Cognitive assessment is an essential element of the screening process of Alzheimer's disease. The prevalence of dementia is increasing and so are the numbers of immigrants and elderly population relocating and in need for health diagnosis and treatment. However, most of the psychometric tools used in psychological assessments are time-consuming and suffer from biases of language and cultural restrictions.

OBJECTIVES

Our objective was to create a computerized version of a multicultural cognitive screening test, which would simplify cognitive assessment of elderly multicultural population, as routine part of health check-up procedures.

METHODS

The application was implemented in Android Studio and was written in Java code with the use of a home PC and a tablet. Rowland Universal Dementia Assessment Scale (RUDAS) was chosen. RUDAS is a cognitive screening tool with good psychological characteristics, which was created for multicultural and bilingual populations and was free to download. The collaboration with an authorized psychologist was essential for the ethics of the psychometric science.

RESULTS

The complete computerized version of RUDAS will include the six-item questionnaire, assessing specific cognitive domains which are in high correlation with Alzheimer's screening process, such as registration, visuospatial orientation, praxis, visuo-constructional drawing, judgment, memory recall and language.

CONCLUSION

The utilization of informatics in making cognitive assessment a user-friendly, validated, not time- or cost-consuming procedure would add value to psychometric tools which still are administered with "pen and paper", when this proceeds with respect to the ethics of the science.

Combining Cognitive Markers to Identify Individuals at Increased Dementia Risk: Influence of Modifying Factors and Time to Diagnosis

OBJECTIVE

We investigated the extent to which combining cognitive markers increases the predictive value for future dementia, when compared to individual markers. Furthermore, we examined whether predictivity of markers differed depending on a range of modifying factors and time to diagnosis.

METHOD

Neuropsychological assessment was performed for 2357 participants (60+ years) without dementia from the population-based Swedish National Study on Aging and Care in Kungsholmen. In the main sample analyses, the outcome was dementia at 6 years. In the time-to-diagnosis analyses, a subsample of 407 participants underwent cognitive testing 12, 6, and 3 years before diagnosis, with dementia diagnosis at the 12-year follow-up.

RESULTS

Category fluency was the strongest individual predictor of dementia 6 years before diagnosis [area under the curve (AUC) = .903]. The final model included tests of verbal fluency, episodic memory, and perceptual speed (AUC = .913); these three domains were found to be the most predictive across a range of different subgroups. Twelve years before diagnosis, pattern comparison (perceptual speed) was the strongest individual predictor (AUC = .686). However, models 12 years before diagnosis did not show significantly increased predictivity above that of the covariates.

CONCLUSIONS

This study shows that combining markers from different cognitive domains leads to increased accuracy in predicting future dementia 6 years later. Markers from the verbal fluency, episodic memory, and perceptual speed domains consistently showed high predictivity across subgroups stratified by age, sex, education, apolipoprotein E ϵ4 status, and dementia type. Predictivity increased closer to diagnosis and showed highest accuracy up to 6 years before a dementia diagnosis. (JINS, 2020, 00, 1-13).

Risk for Alzheimer's disease: A review of long-term episodic memory encoding and retrieval fMRI studies

Many risk factors have been identified that predict future progression to Alzheimer's disease (AD). However, clear links have yet to be made between these risk factors and how they affect brain functioning in early stages of AD. We conducted a narrative review and a quantitative analysis to better understand the relationship between nine categories of AD risk (i.e., brain pathology, genetics/family history, vascular health, head trauma, cognitive decline, engagement in daily life, late-life depression, sex/gender, and ethnoracial group) and task-evoked fMRI activity during episodic memory in cognitively-normal older adults. Our narrative review revealed widespread regional alterations of both greater and lower brain activity with AD risk. Nevertheless, our quantitative analysis revealed that a subset of studies converged on two patterns: AD risk was associated with (1) greater brain activity in frontal and parietal regions, but (2) reduced brain activity in hippocampal and occipital regions. The brain regions affected depended on the assessed memory stage (encoding or retrieval). Although the results clearly indicate that AD risks impact brain activity, we caution against using fMRI as a diagnostic tool for AD at the current time because the above consistencies were present among much variability, even among the same risk factor.

Trajectories of recall memory as predictive of hearing impairment: A longitudinal cohort study

Objectives

Accumulating evidence points to a relationship between hearing function and cognitive ability in later life. However, the exact mechanisms of this relationship are still unclear. This study aimed to characterise latent cognitive trajectories in recall memory and identify their association with subsequent risk of hearing impairment.

Methods

We analysed data from the English Longitudinal Study of Ageing Wave 1 (2002/03) until Wave 7 (2014/15). The study population consisted of 3,615 adults aged 50+ who participated in the first wave of the English Longitudinal Study of Ageing, who had no self-reported hearing impairment in Wave 1, and who underwent a hearing test in Wave 7. Respondents were classified as having hearing impairment if they failed to hear tones quieter than 35 dB HL in the better ear.

Results

The trajectories of recall memory scores were grouped using latent class growth mixture modelling and were related to the presence of hearing impairment in Wave 7. Models estimating 1-class through 5-class recall memory trajectories were compared and the best-fitting models were 4-class trajectories. The different recall memory trajectories represent different starting points and mean of the memory scores. Compared to respondents with the highest recall memory trajectory, other trajectories were increasingly likely to develop later hearing impairment.

Conclusions

Long-term changes in cognitive ability predict hearing impairment. Further research is required to identify the mechanisms explaining the association between cognitive trajectories and hearing impairment, as well as to determine whether intervention for maintenance of cognitive function also give benefit on hearing function among older adults.

Changes in the left temporal microstate are a sign of cognitive decline in patients with Alzheimer's disease

INTRODUCTION

Large-scale brain networks are disrupted in the early stages of Alzheimer's disease (AD). Electroencephalography microstate analysis, a promising method for studying brain networks, parses EEG signals into topographies representing discrete, sequential network activations. Prior studies indicate that patients with AD show a pattern of global microstate disorganization. We investigated whether any specific microstate changes could be found in patients with AD and mild cognitive impairment (MCI) compared to healthy controls (HC).

MATERIALS AND METHODS

Standard EEGs were obtained from 135 HC, 117 patients with MCI, and 117 patients with AD from six Nordic memory clinics. We parsed the data into four archetypal microstates.

RESULTS

There was significantly increased duration, occurrence, and coverage of microstate A in patients with AD and MCI compared to HC. When looking at microstates in specific frequency bands, we found that microstate A was affected in delta (1-4 Hz), theta (4-8 Hz), and beta (13-30 Hz), while microstate D was affected only in the delta and theta bands. Microstate features were able to separate HC from AD with an accuracy of 69.8% and HC from MCI with an accuracy of 58.7%.

CONCLUSIONS

Further studies are needed to evaluate whether microstates represent a valuable disease classifier. Overall, patients with AD and MCI, as compared to HC, show specific microstate alterations, which are limited to specific frequency bands. These alterations suggest disruption of large-scale cortical networks in AD and MCI, which may be limited to specific frequency bands.

Brief Cognitive Tests in the Case of Dementia and Alzheimer's Disease Early Diagnosis

Nowadays, Alzheimer's disease (AD) diagnosis is considered to be a crucial and extremely complex process. Nevertheless, psychometric tools, like Mini-Mental State Evaluation (MMSE), are used to address cognitive function assessment and clinical evaluation processes. However, MMSE's sensitivity in the diagnosis of mild cognitive impairment is debatable in terms of education, age, or nationality. Typical psychometric tools with the use of "paper and pencil" methods combined with physiology measurements are proposed in order to enhance validity and effectiveness in the case of Alzheimer's disease cognitive deficits. The objective of this review study is to highlight the effectiveness of brief cognitive tests (BCT) in the case of dementia and Alzheimer's disease screening. Authors' future work will focus on the application of BCT in MCI diagnosis and evaluation.

Cognitive and neuropsychological examination of the elderly

Neuropsychological assessment plays a prominent role in the evaluation and care of patients with neurodegenerative diseases throughout the dynamic course of disease. As a biomarker of disease, neuropsychological measurement can distinguish normal from pathologic aging processes. Further, neuropsychological data can help distinguish and classify underlying pathologies in dementing diseases, augmenting imaging and biofluid markers in this area. Neuropsychological data can predict increased or reduced risk for dementia conferred by multiple factors, and describe disease trajectory in affected individuals. Cognitive evaluation can also estimate and address functional outcomes that are most important to patients and their loved ones and that are clinically relevant to diagnostic staging. In informing intervention and patient care needs, areas of cognitive weakness highlight targets for support/intervention, while areas of cognitive strength can be capitalized upon to modify the clinical course of disease. These functions can be accomplished through the complementary use of brief screening tools and comprehensive test batteries. However, for neuropsychological data to serve these functions, it is critical to understand neuropsychological test properties and nondisease factors that can account for variance in test performance. This chapter concludes with directions for future research.

The Utility of the National Alzheimer's Coordinating Center's Database for the Rapid Assessment of Evolving Neuropathologic Conditions

The field of dementia research is rapidly evolving, especially with regards to our understanding of the diversity of neuropathologic changes that underlie cognitive decline. Definitions and criteria for known conditions are being periodically revised and refined, and new findings are being made about neuropathologic features associated with dementia status. The database maintained by the National Alzheimer's Coordinating Center (NACC) offer researchers a robust, rapid, and statistically well-powered method to evaluate the implications of newly identified neuropathologic conditions with regards to comorbidities, demographic associations, cognitive status, neuropsychologic tests, radiographic findings, and genetics. NACC data derive from dozens of excellent US Alzheimer disease research centers, which collectively follow thousands of research volunteers longitudinally. Many of the research participants are autopsied using state-of-the-art methods. In this article, we describe the NACC database and give examples of its use in evaluating recently revised neuropathologic diagnoses, including primary age-related tauopathy (PART), limbic predominant age-related TDP-43 encephalopathy (LATE), and the preclinical stage of Alzheimer disease neuropathologic change, based on the National Institute on Aging-Alzheimer's Association consensus guidelines. The dementia research community is encouraged to make use of this readily available database as new neuropathologic changes are recognized and defined in this rapidly evolving field.

Audiovisual integrative training for augmenting cognitive- motor functions in older adults with mild cognitive impairment

BACKGROUND

Previous studies indicated that the behavioral performances of older adults could be enhanced by multisensory integration. This pilot study tested the benefits of an audiovisual integrative (AV) training for improving the cognitive and upper limb motor functions in older adults with mild cognitive impairment (MCI).

METHODS

Twenty participants, according to their MoCA scores, with ten in each of a MCI (mean age = 63.3 years) and healthy older adult group (mean age = 64.7 years), engaged in AV integrative training. They were recruited from the Institute of Active Ageing at the Hong Kong Polytechnic University. The screening was conducted from February to March 2018 and the training program which consisted of three sessions (2 h each) was conducted from 14-28th May 2018. Their executive function, attention and upper limb functions were measured by the Stroop Test and Purdue Pegboard Test respectively.

RESULTS

The mixed linear model analysis results showed significant Time x Group interaction effects in the time used in the Stroop Test (dots) (p = 0.042) and the Purdue Pegboard scores (non-dominant hand use) (p = 0.025). The MCI group exhibited significantly more improvements in attentional control and non-dominant hand motor functions after the training.

CONCLUSIONS

The findings suggest that the AV integrative training has the potential for enhancing the cognitive and motor functions of older adults with MCI. Furthermore, AV integrative training can serve as an alternative non-pharmacological intervention for combating neurodegeneration in older adults.

TRIAL REGISTRATION

This study has been retrospectively registered at the Chinese Clinical Trial Registry which is a World Health Organisation approved registry.

TRIAL REGISTRATION

Current Controlled Trials ChiCTR2000029408, January 29th, 2020.

A Biomarker for Alzheimer's Disease Based on Patterns of Regional Brain Atrophy

Introduction: It has been shown that Alzheimer's disease (AD) is accompanied by marked structural brain changes that can be detected several years before clinical diagnosis via structural magnetic resonance (MR) imaging. In this study, we developed a structural MR-based biomarker for in vivo detection of AD using a supervised machine learning approach. Based on an individual's pattern of brain atrophy a continuous AD score is assigned which measures the similarity with brain atrophy patterns seen in clinical cases of AD. Methods: The underlying statistical model was trained with MR scans of patients and healthy controls from the Alzheimer's Disease Neuroimaging Initiative (ADNI-1 screening). Validation was performed within ADNI-1 and in an independent patient sample from the Open Access Series of Imaging Studies (OASIS-1). In addition, our analyses included data from a large general population sample of the Study of Health in Pomerania (SHIP-Trend). Results: Based on the proposed AD score we were able to differentiate patients from healthy controls in ADNI-1 and OASIS-1 with an accuracy of 89% (AUC = 95%) and 87% (AUC = 93%), respectively. Moreover, we found the AD score to be significantly associated with cognitive functioning as assessed by the Mini-Mental State Examination in the OASIS-1 sample after correcting for diagnosis, age, sex, age·sex, and total intracranial volume (Cohen's f2 = 0.13). Additional analyses showed that the prediction accuracy of AD status based on both the AD score and the MMSE score is significantly higher than when using just one of them. In SHIP-Trend we found the AD score to be weakly but significantly associated with a test of verbal memory consisting of an immediate and a delayed word list recall (again after correcting for age, sex, age·sex, and total intracranial volume, Cohen's f2 = 0.009). This association was mainly driven by the immediate recall performance. Discussion: In summary, our proposed biomarker well differentiated between patients and healthy controls in an independent test sample. It was associated with measures of cognitive functioning both in a patient sample and a general population sample. Our approach might be useful for defining robust MR-based biomarkers for other neurodegenerative diseases, too.

Moderating effect of cognitive reserve on the association between grey matter atrophy and memory varies with age in older adults

BACKGROUND

Educational attainment and verbal intelligence, which indirectly reflect an individual's cognitive reserve (CR), is suggested to buffer the effect of late-life brain degradation on cognitive performance outcome. We aimed to explore how the relationship between whole grey matter volume (GMV) and episodic memory function is altered by CR proxy as well as age in healthy older adults.

METHODS

Elderly Verbal Learning Test (EVLT) and structural magnetic resonance imaging were administered to 110 community-residing older adults. Moderated moderation model tested whether the association between whole GMV and episodic memory was moderated by both CR and chronological age.

RESULTS

The results showed that the moderating effect of CR on Immediate Recall, Short-delay Recall, and Recognition scores of EVLT differed across age groups. The elderly with higher CR showed steeper GMV effect on EVLT at the Age-Younger condition, while such moderating effect was reversed in the Age-Older condition, suggesting an alleviated brain atrophy effect in higher CR elderly.

CONCLUSION

These findings suggest that although higher CR elderly may exhibit earlier GMV-related memory decline, the buffering effect of CR on the cognitive decline due to brain atrophy would become more evident in old-old elderly people who are likely to have accumulated more neuropathological changes. This study underscores chronological age as an important moderating factor in examining the moderating role of CR in late-life memory function.

Neurofilament Light Predicts Decline in Attention but Not Episodic Memory in Preclinical Alzheimer's Disease

BACKGROUND

Cerebrospinal fluid tau and neurofilament light (NfL) are two biomarkers of neurodegeneration in Alzheimer's disease. Previous reports have shown that the influence of tau on cognitive decline depends on levels of amyloid burden whereas NfL predicts decline independently of amyloid. Most studies use a global cognitive composite as the primary outcome, and it is unknown if critical cognitive domain scores are similarly sensitive to rates of decline due to neurodegeneration.

OBJECTIVE

To examine the unique contribution of amyloid, tau, and NfL to rates of cognitive decline in multiple cognitive composites in a cognitively healthy, middle-aged to older adult cohort.

METHODS

A total of 255 participants (55% female; mean age = 66.2 years, range = 42.5-86.7 years) completed CSF studies and serial cognitive assessments to measure global cognition, episodic memory, and attentional control. Linear mixed effects models were used to examine rates of change on each composite score as a function of baseline biomarker levels.

RESULTS

Total tau predicted decline in attention regardless of amyloid status, but the relationship to global cognition and episodic memory was dependent on amyloid, replicating prior literature. NfL predicted decline in attention and global cognition, but not memory, and this effect was independent of amyloid status.

CONCLUSIONS

These findings suggest that NfL can be used to monitor cognitive decline in aging and Alzheimer's disease and that an attentional control composite may be a better outcome for tracking general neurodegenerative effects on cognition.

Linear and nonlinear relationships between cognitive subdomains of ability discrepancy and Alzheimer's disease biomarkers

OBJECTIVE

Substantial research indicates that fluid and crystallized abilities are highly correlated throughout the adult life span. However, recent proposals suggest that a large discrepancy between these two abilities, defined as crystallized performance minus fluid performance, indicates heightened risk for Alzheimer's disease (AD).

METHOD

In 266 cognitively healthy older adults, the present study tested linear and quadratic relationships between an ability discrepancy score and early AD neuropathology indexed via in vivo measures of beta-amyloid deposition and cortical thickness in AD-vulnerable regions. We also tested the extent that alternative forms of this ability discrepancy measure (e.g., subdomain discrepancies, verbal-visual discrepancies) and an episodic memory composite might also be sensitive markers of early AD pathology.

RESULTS

An overall ability discrepancy was linearly and positively correlated with beta- amyloid. A quadratic relationship was found between the overall ability discrepancy score and cortical thickness such that a small positive correlation was found at lower discrepancy levels (fluid > crystallized), but at higher discrepancy levels (crystallized > fluid) a negative relationship was found (i.e., an inverted-U pattern). Similar patterns were found across each subdomain of cognition, but the effects were weaker than the overall ability discrepancy score. Importantly, inclusion of episodic memory (the gold standard) did not alter any of the effects, suggesting that an ability discrepancy confers unique predictiveness of AD biomarkers.

CONCLUSIONS

These findings replicate previous findings and increase the confidence in their usefulness to predict AD biomarkers. Longitudinal validation is needed to clearly relate an ability discrepancy to specific stages of preclinical AD. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Combining Cognitive, Genetic, and Structural Neuroimaging Markers to Identify Individuals with Increased Dementia Risk

Background:

Cognitive and biological markers have shown varying degrees of success in identifying persons who will develop dementia.

Objective: To evaluate different combinations of cognitive and biological markers and identify prediction models with the highest accuracy for identifying persons with increased dementia risk.

Methods:

Neuropsychological assessment, genetic testing (apolipoprotein E –APOE), and structural magnetic resonance imaging (MRI) were performed for 418 older individuals without dementia (60–97 years) from a population-based study (SNAC-K). Participants were followed for six years.

Results:

Cognitive, genetic, and MRI markers were systematically combined to create prediction models for dementia at six years. The most predictive individual markers were perceptual speed or carrying at least one APOEɛ4 allele (AUC = 0.875). The most predictive model (AUC = 0.924) included variables from all three modalities (category fluency, general knowledge, any ɛ4 allele, hippocampal volume, white matter-hyperintensity volume).

Conclusion:

This study shows that combining markers within and between modalities leads to increased predictivity for future dementia. However, minor increases in predictive value should be weighed against the cost of additional tests in larger-scale screening.