Preclinical prediction of AD using neuropsychological tests

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.

Cognitive function based on theta-gamma coupling vs. clinical diagnosis in older adults with mild cognitive impairment with or without major depressive disorder

Whether individuals with mild cognitive impairment (MCI) and a history of major depressive disorder (MDD) are at a higher risk for cognitive decline than those with MCI alone is still not clear. Previous work suggests that a reduction in prefrontal cortical theta phase-gamma amplitude coupling (TGC) is an early marker of cognitive impairment. This study aimed to determine whether using a TGC cutoff is better at separating individuals with MCI or MCI with remitted MDD (MCI+rMDD) on cognitive performance than their clinical diagnosis. Our hypothesis was that global cognition would differ more between TGC-based groups than diagnostic groups. We analyzed data from 128 MCI (mean age: 71.8, SD: 7.3) and 85 MCI+rMDD (mean age: 70.9, SD: 4.7) participants. Participants completed a comprehensive neuropsychological battery; TGC was measured during the N-back task. An optimal TGC cutoff was determined during the performance of the 2-back. This TGC cutoff was used to classify participants into low vs. high-TGC groups. We then compared Cohen's d of the difference in global cognition between the high and low TGC groups to Cohen's d between the MCI and MCI+rMDD groups. We used bootstrapping to determine 95% confidence intervals for Cohen's d values using the whole sample. As hypothesized, Cohen's d for the difference in global cognition between the TGC groups was larger (0.64 [0.32, 0.88]) than between the diagnostic groups (0.10 [0.004, 0.37]) with a difference between these two Cohen's d's of 0.54 [0.10, 0.80]. Our findings suggest that TGC is a useful marker to identify individuals at high risk for cognitive decline, beyond clinical diagnosis. This could be due to TGC being a sensitive marker of prefrontal cortical dysfunction that would lead to an accelerated cognitive decline.

Effects of healthy aging and mnemonic strategies on verbal memory performance across the adult lifespan: Mediating role of posterior hippocampus

In this study, we aimed to understand the contributions of hippocampal anteroposterior subregions (head, body, tail) and subfields (cornu ammonis 1-3 [CA1-3], dentate gyrus [DG], and subiculum [Sub]) and encoding strategies to the age-related verbal memory decline. Healthy participants were administered the California Verbal Learning Test-II to evaluate verbal memory performance and encoding strategies and underwent 4.7 T magnetic resonance imaging brain scan with subsequent hippocampal subregions and subfields manual segmentation. While total hippocampal volume was not associated with verbal memory performance, we found the volumes of the posterior hippocampus (body) and Sub showed significant effects on verbal memory performance. Additionally, the age-related volume decline in hippocampal body volume contributed to lower use of semantic clustering, resulting in lower verbal memory performance. The effect of Sub on verbal memory was statistically independent of encoding strategies. While total CA1-3 and DG volumes did not show direct or indirect effects on verbal memory, exploratory analyses with DG and CA1-3 volumes within the hippocampal body subregion suggested an indirect effect of age-related volumetric reduction on verbal memory performance through semantic clustering. As semantic clustering is sensitive to age-related hippocampal volumetric decline but not to the direct effect of age, further investigation of mechanisms supporting semantic clustering can have implications for early detection of cognitive impairments and decline.

Increased neural differentiation after a single session of aerobic exercise in older adults

Aging is associated with decreased cognitive function. One theory posits that this decline is in part due to multiple neural systems becoming dedifferentiated in older adults. Exercise is known to improve cognition in older adults, even after only a single session. We hypothesized that one mechanism of improvement is a redifferentiation of neural systems. We used a within-participant, cross-over design involving 2 sessions: either 30 minutes of aerobic exercise or 30 minutes of seated rest (n = 32; ages 55-81 years). Both functional Magnetic Resonance Imaging (fMRI) and Stroop performance were acquired soon after exercise and rest. We quantified neural differentiation via general heterogeneity regression. There were 3 prominent findings following the exercise. First, participants were better at reducing Stroop interference. Second, while there was greater neural differentiation within the hippocampal formation and cerebellum, there was lower neural differentiation within frontal cortices. Third, this greater neural differentiation in the cerebellum and temporal lobe was more pronounced in the older ages. These data suggest that exercise can induce greater neural differentiation in healthy aging.

Prevalence and localization of nocturnal epileptiform discharges in mild cognitive impairment

Recent evidence shows that identifying and treating epileptiform abnormalities in patients with Alzheimer's disease could represent a potential avenue to improve clinical outcome. Specifically, animal and human studies have revealed that in the early phase of Alzheimer's disease, there is an increased risk of seizures. It has also been demonstrated that the administration of anti-seizure medications can slow the functional progression of the disease only in patients with EEG signs of cortical hyperexcitability. In addition, although it is not known at what disease stage hyperexcitability emerges, there remains no consensus regarding the imaging and diagnostic methods best able to detect interictal events to further distinguish different phenotypes of Alzheimer's disease. In this exploratory work, we studied 13 subjects with amnestic mild cognitive impairment and 20 healthy controls using overnight high-density EEG with 256 channels. All participants also underwent MRI and neuropsychological assessment. Electronic source reconstruction was also used to better select and localize spikes. We found spikes in six of 13 (46%) amnestic mild cognitive impairment compared with two of 20 (10%) healthy control participants (P = 0.035), representing a spike prevalence similar to that detected in previous studies of patients with early-stage Alzheimer's disease. The interictal events were low-amplitude temporal spikes more prevalent during non-rapid eye movement sleep. No statistically significant differences were found in cognitive performance between amnestic mild cognitive impairment patients with and without spikes, but a trend in immediate and delayed memory was observed. Moreover, no imaging findings of cortical and subcortical atrophy were found between amnestic mild cognitive impairment participants with and without epileptiform spikes. In summary, our exploratory study shows that patients with amnestic mild cognitive impairment reveal EEG signs of hyperexcitability early in the disease course, while no other significant differences in neuropsychological or imaging features were observed among the subgroups. If confirmed with longitudinal data, these exploratory findings could represent one of the first signatures of a preclinical epileptiform phenotype of amnestic mild cognitive impairment and its progression.

The NeuroBel: A Screening Test for Verbal Language Impairment in Spanish-Speaking Elderly People With Cognitive Decline

PURPOSE

The NeuroBel is a short test that can detect cognitive decline using language tasks. This study replicated previous research using larger clinical samples from three Spanish-speaking countries.

METHOD

Eight tasks were used to analyze verbal language functioning using a psycholinguistic approach. A total of 232 elderly, monolingual Spanish speakers from Spain, Cuba, and Colombia participated in this study. Of these, 76 had Alzheimer's disease (AD) in the initial phase, 75 had mild cognitive impairment (MCI), and 81 did not exhibit cognitive impairment (healthy controls).

RESULTS

Significant differences were observed among the three clinical groups. The participants with AD and the participants with MCI had significantly lower NeuroBel scores than the control group on most of the tasks. However, repetition (in AD vs. MCI) and auditory lexical decision (in MCI vs. control) tasks were not significant in Tukey's post hoc tests. Discriminant analysis showed that 80.6% of the participants were correctly classified into the original groups and revealed the tasks that were the best and worst for differentiating among groups. The receiver-operating characteristic curves showed high sensitivity for AD and MCI. The area under the curve was .97 in the contrast of AD versus MCI + controls, .96 in the determination of overall cognitive decline (AD + MCI vs. controls), and .93 in the contrast of MCI and control groups.

CONCLUSION

This study confirmed that the NeuroBel is a suitable test for detecting cognitive decline based on language impairment in Spanish-speaking elderly people.

Multiple sclerosis lesions that impair memory map to a connected memory circuit

BACKGROUND

Nearly 1 million Americans are living with multiple sclerosis (MS) and 30-50% will experience memory dysfunction. It remains unclear whether this memory dysfunction is due to overall white matter lesion burden or damage to specific neuroanatomical structures. Here we test if MS memory dysfunction is associated with white matter lesions to a specific brain circuit.

METHODS

We performed a cross-sectional analysis of standard structural images and verbal memory scores as assessed by immediate recall trials from 431 patients with MS (mean age 49.2 years, 71.9% female) enrolled at a large, academic referral center. White matter lesion locations from each patient were mapped using a validated algorithm. First, we tested for associations between memory dysfunction and total MS lesion volume. Second, we tested for associations between memory dysfunction and lesion intersection with an a priori memory circuit derived from stroke lesions. Third, we performed mediation analyses to determine which variable was most associated with memory dysfunction. Finally, we performed a data-driven analysis to derive de-novo brain circuits for MS memory dysfunction using both functional (n = 1000) and structural (n = 178) connectomes.

RESULTS

Both total lesion volume (r = 0.31, p < 0.001) and lesion damage to our a priori memory circuit (r = 0.34, p < 0.001) were associated with memory dysfunction. However, lesion damage to the memory circuit fully mediated the association of lesion volume with memory performance. Our data-driven analysis identified multiple connections associated with memory dysfunction, including peaks in the hippocampus (T = 6.05, family-wise error p = 0.000008), parahippocampus, fornix and cingulate. Finally, the overall topography of our data-driven MS memory circuit matched our a priori stroke-derived memory circuit.

CONCLUSIONS

Lesion locations associated with memory dysfunction in MS map onto a specific brain circuit centered on the hippocampus. Lesion damage to this circuit fully mediated associations between lesion volume and memory. A circuit-based approach to mapping MS symptoms based on lesions visible on standard structural imaging may prove useful for localization and prognosis of higher order deficits in MS.

Cognitive training based on functional near-infrared spectroscopy neurofeedback for the elderly with mild cognitive impairment: a preliminary study

Introduction

Mild cognitive impairment (MCI) is often described as an intermediate stage of the normal cognitive decline associated with aging and dementia. There is a growing interest in various non-pharmacological interventions for MCI to delay the onset and inhibit the progressive deterioration of daily life functions. Previous studies suggest that cognitive training (CT) contributes to the restoration of working memory and that the brain-computer-interface technique can be applied to elicit a more effective treatment response. However, these techniques have certain limitations. Thus, in this preliminary study, we applied the neurofeedback paradigm during CT to increase the working memory function of patients with MCI.

Methods

Near-infrared spectroscopy (NIRS) was used to provide neurofeedback by measuring the changes in oxygenated hemoglobin in the prefrontal cortex. Thirteen elderly MCI patients who received CT-neurofeedback sessions four times on the left dorsolateral prefrontal cortex (dlPFC) once a week were recruited as participants.

Results

Compared with pre-intervention, the activity of the targeted brain region increased when the participants first engaged in the training; after 4 weeks of training, oxygen saturation was significantly decreased in the left dlPFC. The participants demonstrated significantly improved working memory compared with pre-intervention and decreased activity significantly correlated with improved cognitive performance.

Conclusion

Our results suggest that the applications for evaluating brain-computer interfaces can aid in elucidation of the subjective mental workload that may create additional or decreased task workloads due to CT.

The mitochondria-targeted small molecule SS31 delays progression of behavioral deficits by attenuating β-amyloid plaque formation and mitochondrial/synaptic deterioration in APP/PS1 mice

Alzheimer's disease (AD) is a common neurodegenerative disorder characterized by progressive cognitive dysfunction and an impaired ability to carry out daily life functions. Mitochondrial dysfunction and β-amyloid (Aβ) deposition are the most common causes of AD. Antioxidants have been shown to delay brain aging and AD development; however, it remains unknown whether the antioxidant peptide SS31 can protect mitochondrial and synaptic function and delay the progression of behavioral deficits in early-stage AD in vivo. Therefore, in this study we compared mitochondrial and synaptic changes, as well as the protective effects of SS31, in APP/PS1 transgenic mice and C57BL/6J control mice. The APP/PS1 transgenic mice exhibited elevated expression of Aβ40/Aβ42 and mitochondrial fission protein DLP1 and reduced expression of synaptophysin (SYN) and postsynaptic density protein 95 (PSD95) reductions, as well as increased levels of neuronal apoptosis and ROS in the hippocampus, and long-term treatment with SS31 reversed these effects. Furthermore, the cognitive impairments observed in APP/PS1 transgenic mice were reversed by SS31 treatment. Our findings show that SS31 lowers ROS and Aβ levels, protecting mitochondrial homeostasis and synaptic integrity, and ultimately improving behavioral deficits in early-stage AD. This suggests that SS31 is a potential pharmacological agent for treating or slowing the progression of AD.

One-year prediction of cognitive decline following cognitive-stimulation from real-world data

Clinical evidence based on real-world data (RWD) is accumulating exponentially providing larger sample sizes available, which demand novel methods to deal with the enhanced heterogeneity of the data. Here, we used RWD to assess the prediction of cognitive decline in a large heterogeneous sample of participants being enrolled with cognitive stimulation, a phenomenon that is of great interest to clinicians but that is riddled with difficulties and limitations. More precisely, from a multitude of neuropsychological Training Materials (TMs), we asked whether was possible to accurately predict an individual's cognitive decline one year after being tested. In particular, we performed longitudinal modelling of the scores obtained from 215 different tests, grouped into 29 cognitive domains, a total of 124,610 instances from 7902 participants (40% male, 46% female, 14% not indicated), each performing an average of 16 tests. Employing a machine learning approach based on ROC analysis and cross-validation techniques to overcome overfitting, we show that different TMs belonging to several cognitive domains can accurately predict cognitive decline, while other domains perform poorly, suggesting that the ability to predict decline one year later is not specific to any particular domain, but is rather widely distributed across domains. Moreover, when addressing the same problem between individuals with a common diagnosed label, we found that some domains had more accurate classification for conditions such as Parkinson's disease and Down syndrome, whereas they are less accurate for Alzheimer's disease or multiple sclerosis. Future research should combine similar approaches to ours with standard neuropsychological measurements to enhance interpretability and the possibility of generalizing across different cohorts.

Changes in executive function in the Canadian longitudinal study on aging over 3-years: A focus on social determinants of health

Maintaining executive functions, including planning, inhibition, and decision-making skills, is important for autonomy and activities of daily living. There is a growing body of evidence linking social determinants and cognitive aging, but less is known about the potential role of social determinants in changes in executive functioning over time. Using data from the Canadian Longitudinal Study on Aging (CLSA), a large cohort of mid-aged and older adults, we examined changes in executive function over a 3-year period. Specifically, we focused on the role of social determinants (i.e., social positioning, social support, education) in explaining these changes. Executive function was measured at baseline and follow-up 3 years later using the Mental Alteration Test (MAT). We computed a reliable change index (RCI) and used a multiple linear regression model to examine the associations between known correlates and change in executive function over the 3-year period (n = 29,344). Older age, higher household income, and greater educational attainment predicted declines in executive function. Health factors (e.g., depression symptoms, physical activity levels) and many social determinants (sexual orientation, gender identity, race, and perceived social standing) were not associated with change in executive function. These results suggest that social determinants of health may be related to initial differences in cognitive functioning (i.e., cross-sectional differences) rather than more rapid cognitive aging.

Investigating the relationship between specific executive functions and functional decline among community-dwelling older adults: results from a prospective pilot study

BACKGROUND

As cognitive functions and, more specifically, executive functions (EF) seem to influence autonomy among the elderly, we investigated the role of each of the five EF sub-components (inhibition, spontaneous flexibility, reactive flexibility, planning, and updating in working memory) for the risk of functional decline.

METHOD

A total of 137 community-dwelling participants over 75 years of age were included in a prospective cohort study and assigned to three groups: individuals with neuro-degenerative cognitive disorders, those having cognitive disorders with non-degenerative aetiology, and a control group without any cognitive problems. We measured each EF sub-component and assessed functional decline by evaluating basic (b-ADL) and instrumental activities of daily living (i-ADL) at baseline and 6 months later. We conducted three separate multiple logistic regression models to examine the extent to which the five EF facets predicted overall functional decline at the end of the follow-up period.

RESULTS

We found that people who exhibited a decline in b-ADLs or/and i-ADLs over 6 months had worse performance on inhibition and two flexibility tasks than those who did not experience a decline. The results suggest that decliners have more difficulties in managing unforeseen events. Inhibition and updating in working memory predicted a decline in b-ADL while spontaneous and reactive flexibilities predicted a decline in i-ADL.

CONCLUSION

In our sample, specific executive dysfunctions were associated with a decline in functional status. With respect to the risk of decline in b-ADL, deficits in inhibition may represent a risk factor, as it regulates over-learned activities. Bothtypes of flexibility, which allow the shifting and generating of adaptive responses, predicted decline in i-ADL. In sum, paying more attention to particular EF profiles would help clinicians to anticipate some aspects of functional decline.

Language performance as a prognostic factor for developing Alzheimer's clinical syndrome and mild cognitive impairment: Results from the population-based HELIAD cohort

OBJECTIVES

There is limited research on the prognostic value of language tasks regarding mild cognitive impairment (MCI) and Alzheimer's clinical syndrome (ACS) development in the cognitively normal (CN) elderly, as well as MCI to ACS conversion.

METHODS

Participants were drawn from the population-based Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) cohort. Language performance was evaluated via verbal fluency [semantic (SVF) and phonemic (PVF)], confrontation naming [Boston Naming Test short form (BNTsf)], verbal comprehension, and repetition tasks. An additional language index was estimated using both verbal fluency tasks: SVF-PVF discrepancy. Cox proportional hazards analyses adjusted for important sociodemographic parameters (age, sex, education, main occupation, and socioeconomic status) and global cognitive status [Mini Mental State Examination score (MMSE)] were performed.

RESULTS

A total of 959 CN and 118 MCI older (>64 years) individuals had follow-up investigations after a mean of ∼3 years. Regarding the CN group, each standard deviation increase in the composite language score reduced the risk of ACS and MCI by 49% (8-72%) and 32% (8-50%), respectively; better SVF and BNTsf performance were also independently associated with reduced risk of ACS and MCI. On the other hand, using the smaller MCI participant set, no language measurement was related to the risk of MCI to ACS conversion.

CONCLUSIONS

Impaired language performance is associated with elevated risk of ACS and MCI development. Better SVF and BNTsf performance are associated with reduced risk of ACS and MCI in CN individuals, independent of age, sex, education, main occupation, socioeconomic status, and MMSE scores at baseline.

Early detection of Alzheimer's disease using neuropsychological tests: a predict-diagnose approach using neural networks

Alzheimer’s disease (AD) is a slowly progressing disease for which there is no known therapeutic cure at present. Ongoing research around the world is actively engaged in the quest for identifying markers that can help predict the future cognitive state of individuals so that measures can be taken to prevent the onset or arrest the progression of the disease. Researchers are interested in both biological and neuropsychological markers that can serve as good predictors of the future cognitive state of individuals. The goal of this study is to identify non-invasive, inexpensive markers and develop neural network models that learn the relationship between those markers and the future cognitive state. To that end, we use the renowned Alzheimer’s Disease Neuroimaging Initiative (ADNI) data for a handful of neuropsychological tests to train Recurrent Neural Network (RNN) models to predict future neuropsychological test results and Multi-Level Perceptron (MLP) models to diagnose the future cognitive states of trial participants based on those predicted results. The results demonstrate that the predicted cognitive states match the actual cognitive states of ADNI test subjects with a high level of accuracy. Therefore, this novel two-step technique can serve as an effective tool for the prediction of Alzheimer’s disease progression. The reliance of the results on inexpensive, non-invasive tests implies that this technique can be used in countries around the world including those with limited financial resources.

The Association Between Cognitive Impairment and Subsequent Falls Among Older Adults: Evidence From the China Health and Retirement Longitudinal Study

Introduction

Previous studies have suggested that cognitive impairment is associated with falls in older adults. However, the consistency of results among different subgroups defined by multiple characteristics of the elderly has not yet been tested. Additionally, results are inconsistent regarding the effects of different cognitive domains on falls. Therefore, this study sought to use representative data from a nationwide study to better understand the longitudinal association between cognitive impairment and subsequent falls in older adults.

Methods

The current study was conducted based on the China Health and Retirement Longitudinal Study (CHARLS) data of respondents aged ≥60 years in 2015 and the fall data in 2018. The respondents were divided into subgroups according to different demographic characteristics. Multiple logistic regression analysis was conducted to adjust for various confounding factors and evaluate the association between cognitive impairment and falls.

Results

Of the 5,110 respondents included in this study, 1,093 (21.39%) had falls within the last 2 years. A significant association was found between cognitive impairment and subsequent falls (OR = 0.97, 95% CI 0.95–0.99, P = 0.001) after adjusting for all of the covariates related to falls. Analysis of different cognitive domains showed that orientation (OR = 0.94, 95% CI 0.90–0.99, P = 0.013) and memory (OR = 0.93, 95% CI 0.90–0.97, P = 0.001) were significantly associated with falls. In subgroup analysis, the ORs of people aged 60–74 years, male, with lower education level were 0.97 (95% CI 0.95–0.99, P = 0.008), 0.96 (95% CI 0.93–0.98, P = 0.001), and 0.97 (95% CI 0.95–0.99, P = 0.001), respectively, suggesting that the associations were also statistically significant in these subgroups. There was also a significant association both in urban (OR = 0.97, 95% CI 0.95–0.99, P = 0.001) and in rural residents (OR = 0.97, 95% CI 0.95–0.99, P = 0.003).

Conclusions

Our results suggest that the associations between cognition and falls vary depending on the different demographic characteristics of older adults. These findings may be useful for designing more accurate identification and intervention for the fall risk for specific high-risk groups.

Locus coeruleus integrity is related to tau burden and memory loss in autosomal-dominant Alzheimer's disease

Abnormally phosphorylated tau, an indicator of Alzheimer's disease, accumulates in the first decades of life in the locus coeruleus (LC), the brain's main noradrenaline supply. However, technical challenges in in-vivo assessments have impeded research into the role of the LC in Alzheimer's disease. We studied participants with or known to be at-risk for mutations in genes causing autosomal-dominant Alzheimer's disease (ADAD) with early onset, providing a unique window into the pathogenesis of Alzheimer's largely disentangled from age-related factors. Using high-resolution MRI and tau PET, we found lower rostral LC integrity in symptomatic participants. LC integrity was associated with individual differences in tau burden and memory decline. Post-mortem analyses in a separate set of carriers of the same mutation confirmed substantial neuronal loss in the LC. Our findings link LC degeneration to tau burden and memory in Alzheimer's, and highlight a role of the noradrenergic system in this neurodegenerative disease.

Low Subicular Volume as an Indicator of Dementia-Risk Susceptibility in Old Age

Introduction

Hippocampal atrophy is an established Alzheimer’s Disease (AD) biomarker. Volume loss in specific subregions as measurable with ultra-high field magnetic resonance imaging (MRI) may reflect earliest pathological alterations.

Methods

Data from positron emission tomography (PET) for estimation of cortical amyloid β (Aβ) and high-resolution 7 Tesla T1 MRI for assessment of hippocampal subfield volumes were analyzed in 61 non-demented elderly individuals who were divided into risk-categories as defined by high levels of cortical Aβ and low performance in standardized episodic memory tasks.

Results

High cortical Aβ and low episodic memory interactively predicted subicular volume [F(3,57) = 5.90, p = 0.018]. The combination of high cortical Aβ and low episodic memory was associated with significantly lower subicular volumes, when compared to participants with high episodic memory (p = 0.004).

Discussion

Our results suggest that low subicular volume is linked to established indicators of AD risk, such as increased cortical Aβ and low episodic memory. Our data support subicular volume as a marker of dementia-risk susceptibility in old-aged non-demented persons.

Exosomes in Age-Related Cognitive Decline: Mechanistic Insights and Improving Outcomes

Aging is the most prominent risk factor for cognitive decline, yet behavioral symptomology and underlying neurobiology can vary between individuals. Certain individuals exhibit significant age-related cognitive impairments, while others maintain intact cognitive functioning with only minimal decline. Recent developments in genomic, proteomic, and functional imaging approaches have provided insights into the molecular and cellular substrates of cognitive decline in age-related neuropathologies. Despite the emergence of novel tools, accurately and reliably predicting longitudinal cognitive trajectories and improving functional outcomes for the elderly remains a major challenge. One promising approach has been the use of exosomes, a subgroup of extracellular vesicles that regulate intercellular communication and are easily accessible compared to other approaches. In the current review, we highlight recent findings which illustrate how the analysis of exosomes can improve our understanding of the underlying neurobiological mechanisms that contribute to cognitive variation in aging. Specifically, we focus on exosome-mediated regulation of miRNAs, neuroinflammation, and aggregate-prone proteins. In addition, we discuss how exosomes might be used to enhance individual patient outcomes by serving as reliable biomarkers of cognitive decline and as nanocarriers to deliver therapeutic agents to the brain in neurodegenerative conditions.

Prognostic Value of Learning and Retention Measures from the Free and Cued Selective Reminding Test to Identify Incident Mild Cognitive Impairment

OBJECTIVE

To compare the predictive validity of learning and retention measures from the picture version of the Free and Cued Selective Reminding Test with Immediate Recall (pFCSRT + IR) for identifying incident mild cognitive impairment (MCI).

METHODS

Learning was defined by the sum of free recall (FR) and retention by delayed free recall (DFR) tested 15-20 min later. Totally, 1422 Baltimore Longitudinal Study of Aging (BLSA) participants (mean age 69.6 years, 54% male, mean 16.7 years of education) without dementia or MCI received the pFCSRT + IR at baseline and were followed longitudinally. Cox proportional hazards models were used to evaluate the effect of baseline learning and retention on risk of MCI.

RESULTS

In total, 187 participants developed MCI over a median of 8.1 years of follow-up. FR and DFR each predicted incident MCI adjusting for age, sex, and education. Also, each independently predicted incident MCI in the presence of the other with similar effect sizes: around 20% decrease in the hazard of MCI corresponding to one standard deviation increase in FR or DFR.

CONCLUSION

The practice of preferring retention over learning to predict incident MCI should be reconsidered. The decision to include retention should be guided by time constraints and patient burden.

Unraveling the Cognitive-Motor Interaction in Individuals With Amnestic Mild Cognitive Impairment

PURPOSE

This study aimed to determine whether increasing the contribution of executive functions worsens dual-task performance in individuals with amnestic mild cognitive impairment (aMCI).

METHODS

Fourteen individuals with aMCI (mean [SD]: 74 [4] years) and 19 control adults (71 [5] years) recalled a list of letters in the order of presentation (SPAN-O) or in alphabetic order (SPAN-A) while ascending or descending a 3-step staircase. Dual-task cost (DTC) represented the average decrement of motor and cognitive performances during dual tasks, with greater DTC indicating worse performance.

RESULTS

SPAN-A (P < 0.001) and stair descent (P = 0.023) increased the DTC in both groups compared with SPAN-O and stair ascent. Furthermore, individuals with aMCI had a greater DTC (93.4 [41.2]%) than the control group (48.3 [27.9]%) for SPAN-A (P < 0.001). Dual-task cost was also greater in descent (76.6 [42.1]%) than ascent (64.0 [34.5]%) in individuals with aMCI (P = 0.024) but not in the control group (P = 0.99). Significant negative partial correlations (β < -0.39; P < 0.05) were found between Montreal Cognitive Assessment score and DTC, while controlling for age and physical function.

DISCUSSION AND CONCLUSIONS

A greater DTC in individuals with aMCI when the cognitive task requires working memory (SPAN-A) or during complex locomotor task (descent) suggests that aMCI impedes the capacity to perform 2 tasks simultaneously when higher-order cognitive processes are challenged. Furthermore, a greater DTC in our dual-task situations appears to reflect cognitive decline, as assessed by the Montreal Cognitive Assessment score. Overall, this study indicates that increasing the contribution of executive functions worsens the cognitive-motor interaction in individuals with aMCI.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A375).

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.

Dual feature correlation guided multi-task learning for Alzheimer's disease prediction

Alzheimer's disease (AD) is a gradually progressive neurodegenerative disease affecting cognition functions. Predicting the cognitive scores from neuroimage measures and identifying relevant imaging biomarkers are important research topics in the study of AD. Despite machine learning algorithms having many successful applications, the prediction model suffers from the so-called curse of dimensionality. Multi-task feature learning (MTFL) has helped tackle this problem incorporating the correlations among multiple clinical cognitive scores. However, MTFL neglects the inherent correlation among brain imaging measures. In order to better predict the cognitive scores and identify stable biomarkers, we first propose a generalized multi-task formulation framework that incorporates the task and feature correlation structures simultaneously. Second, we present a novel feature-aware sparsity-inducing norm (FAS-norm) penalty to incorporate a useful correlation between brain regions by exploiting correlations among features. Three multi-task learning models that incorporate the FAS-norm penalty are proposed following our framework. Finally, the algorithm based on the alternating direction method of multipliers (ADMM) is developed to optimize the non-smooth problems. We comprehensively evaluate the proposed models on the cross-sectional and longitudinal Alzheimer's disease neuroimaging initiative datasets. The inputs are the thickness measures and the volume measures of the cortical regions of interest. Compared with MTFL, our methods achieve an average decrease of 4.28% in overall error in the cross-sectional analysis and an average decrease of 7.97% in the Alzheimer's Disease Assessment Scale cognitive total score longitudinal analysis. Moreover, our methods identify sensitive and stable biomarkers to physicians, such as the hippocampus, lateral ventricle, and corpus callosum.

Advancing Smart Home Awareness-A Conceptual Computational Modelling Framework for the Execution of Daily Activities of People with Alzheimer's Disease

Utilizing context-aware tools in smart homes (SH) helps to incorporate higher quality interaction paradigms between the house and specific groups of users such as people with Alzheimer's disease (AD). One method of delivering these interaction paradigms acceptably and efficiently is through context processing the behavior of the residents within the SH. Predicting human behavior and uncertain events is crucial in the prevention of upcoming missteps and confusion when people with AD perform their daily activities. Modelling human behavior and mental states using cognitive architectures produces computational models capable of replicating real use case scenarios. In this way, SHs can reinforce the execution of daily activities effectively once they acquire adequate awareness about the missteps, interruptions, memory problems, and unpredictable events that can arise during the daily life of a person living with cognitive deterioration. This paper presents a conceptual computational framework for the modelling of daily living activities of people with AD and their progression through different stages of AD. Simulations and initial results demonstrate that it is feasible to effectively estimate and predict common errors and behaviors in the execution of daily activities under specific assessment tests.

Short-term memory, attention, and temporal orientation as predictors of the cognitive impairment in older adults: A cross-sectional observational study

Late-life cognitive decline ranges from the mildest cases of normal, age-related change to mild cognitive impairment to severe cases of dementia. Dementia is the largest global burden for the 21st century welfare and healthcare systems. The aim of this study was to analyze the neuropsychological constructs (temporal orientation (TO), spatial orientation (SO), fixation memory (FM), attention (A), calculation (C), short-term memory (STM), language (L), and praxis (P)), semantic fluency, level of functionality, and mood that reveal the greatest deficit in the different stages ranging from normal cognition (NC) to cognitive impairment in older adults in a primary healthcare setting. The study included 337 participants (102 men, 235 women), having a mean age of 74 ± 6 years. According to their scores on the Spanish version of the Mini-Mental State Examination (MEC-35), subjects were divided into 4 groups: no deterioration (ND) (score 32-35), subtle cognitive impairment (SCI) (score 28-31), level deterioration (LD) (score 24-27) and moderate deterioration (MD) (score 20-23). The ND group revealed significant differences in TO, STM, C, A, L, P, and S-T as compared to the other groups. The MD group (in all the neuropsychological constructs) and the ND and SCI groups showed significant differences on the Yesavage geriatric depression scale (GDS-15). All except the FM neuropsychological construct were part of the MEC-35 prediction model and all of the regression coefficients were significant for these variables in the model. Furthermore, the highest average percentage of relative deterioration occurs between LD and MD and the greatest deterioration is observed in the STM for all groups, including A and TO for the LD and MD groups. Based on our findings, community programs have been implemented that use cognitive stimulation to prevent cognitive decline and to maintain the neuropsychological constructs.

Chronic kidney disease, physical activity, and cognitive function in older adults- results from the National Health and Nutrition Examination Survey (2011-2014)

BACKGROUND

Cognitive impairment is common among persons with chronic kidney disease (CKD) due in part to reduced kidney function. Given that physical activity (PA) is known to mitigate cognitive decline, we examined whether associations between CKD stage and global/domain-specific cognitive function differs by PA.

METHODS

We leveraged 3,223 participants (aged≥60years) enrolled in National Health and Nutrition Examination Survey (NHANES,2011-2014), with at least one measure of objective cognitive function (immediate recall [CERAD-WL], delayed recall [CERAD-DR], verbal fluency [AF], executive function/processing speed [DSST], global [average of 4 tests]) or self-perceived memory decline [SCD]. We quantified the association between CKD stage (no CKD: eGFR≥60 mL/min/1.73m2 and albuminuria(ACR)<30 mg/g; stage G1-G3: eGFR≥60mL/min/1.73m2 and ACR≥30mg/g or eGFR 30-59mL/min/1.73m2; stage G4-G5: eGFR<30mL/min/1.73m2) and cognitive function using linear regression (objective measures) and logistic regression (SCD), accounting for sampling weights for nationally-representative estimates. We tested whether associations differed by physical activity (Global Physical Activity Questionnaire, high PA≥600MET*min/week vs. low PA<600MET*min/week) using a Wald test.

RESULTS

Among NHANES participants, 34.9% had CKD stageG1-G3, 2.6% had stageG4-G5, and 50.7% had low PA. CKD stageG4-G5 was associated with lower global cognitive function (difference = -0.38SD, 95%CI:-0.62,-0.15). This association differed by PA (pinteraction = 0.01). Specifically, among participants with low PA, those with CKD stageG4-G5 had lower global cognitive function (difference = -0.57SD, 95%CI: -0.82,-0.31) compared to those without CKD. Among those with high PA, no difference was found (difference = 0.10SD, 95%CI:-0.29,0.49). Similarly, CKD stage was only associated with immediate recall, verbal fluency, executive function, and processing speed among those with low PA; no associations were observed for delayed recall or self-perceived memory decline.

CONCLUSIONS

CKD is associated with lower objective cognitive function among those with low, but not high PA. Clinicians should consider screening older patients with CKD who have low PA for cognitive impairment and encourage them to meet PA guidelines.

The Eyes Are More Eloquent Than Words: Anticipatory Looking as an Index of Event Memory in Alzheimer's Disease

Alzheimer's disease (AD) is a disorder in which individuals experience a difficulty in maintaining event memory for when, where, who, and what. However, verbal deficiency, one of the other symptoms of AD, may prevent a precise diagnosis of event memory because existing tests are based on verbal instructions by the tester and verbal response from patient. Therefore, non-verbal methods are essential to evaluate event memory in AD. The present study, using eye tracking, investigated whether AD patients deployed anticipatory looking to target acts related to future events based on previous experience when an identical video was presented to them twice. The results revealed the presence of anticipatory looking, although AD patients were unable to verbally report the content of the video. Our results illustrate that AD patients have a one-time event memory better than previously thought.

Decreased Plasma Level of Lipoprotein Lipase Predicted Verbal Disfluency in Chinese Type 2 Diabetes Mellitus Patients with Early Cognitive Deficits

BACKGROUND

Lipoprotein Lipase (LPL) is the rate-limiting enzyme catalyzing the hydrolysis of triglycerides and contributes to the amyloid-β formation, which shows promise as a pathological factor of cognitive decline in Type 2 Diabetes Mellitus (T2DM). This study aimed to investigate the pathogenetic roles of LPL and rs328 polymorphism in Mild Cognitive Impairment (MCI) in patients with T2DM.

METHODS

Chinese patients with T2DM were recruited and divided into two groups based on the Montreal Cognitive Assessment score. Demographic data were collected, LPL was measured and neuropsychological test results were examined.

RESULTS

Seventy-nine patients with diabetes and MCI had significantly decreased plasma LPL levels (p = 0.007) when compared with health-cognition controls (n = 91). Correlation analysis revealed that LPL was positively correlated with clock drawing test (r = 0.158, p = 0.043) and logical memory test (r = 0.162, p = 0.037), while lipoprotein a (r = -0.214, p = 0.006) was inversely associated with LPL. Logistic regression analysis further demonstrated that LPL concentration was an independent factor for diabetic MCI (p = 0.036). No significant differences were observed in the distributions of rs328 variants between patients with MCI and the controls. Moreover, no remarkable association was found among plasma LPL levels, cognitive performances, and lipid levels between the genotypic subgroups. The trail making test A was increased in the GC group when compared with the CC genotype in the control group.

CONCLUSION

Decreased plasma level of LPL could probably predict early cognitive deficits, especially verbal disfluency.

Progressive impairments in executive function in the APP/PS1 model of Alzheimer's disease as measured by translatable touchscreen testing

Executive function deficits in Alzheimer's disease (AD) occur early in disease progression and may be predictive of cognitive decline. However, no preclinical studies have identified deficits in rewarded executive function in the commonly used APPSwe/PS1∆E9 (APP/PS1) mouse model. To address this, we assessed 12-26 month old APP/PS1 mice on rewarded reversal and/or extinction tasks. 16-month-old, but not 13- or 26-month-old, APP/PS1 mice showed an attenuated rate of extinction. Reversal deficits were seen in 22-month-old, but not 13-month-old APP/PS1 animals. We then confirmed that impairments in reversal were unrelated to previously reported visual impairments in both AD mouse models and humans. Age, but not genotype, had a significant effect on markers of retinal health, indicating the deficits seen in APP/PS1 mice were directly related to cognition. This is the first characterisation of rewarded executive function in APP/PS1 mice, and has great potential to facilitate translation from preclinical models to the clinic.

Amyloid-Beta Influences Memory via Functional Connectivity During Memory Retrieval in Alzheimer's Disease

Objective: Amnesia in Alzheimer's disease (AD) appears early and could be caused by encoding deficiency, consolidation dysfunction, and/or impairment in the retrieval of stored memory information. The relationship between AD pathology biomarker β-amyloid and memory dysfunction is unclear. Method: The memory task functional MRI and amyloid PET were simultaneously performed to investigate the relationship between memory performance, memory phase-related functional connectivity, and cortical β-amyloid deposition. We clustered functional networks during memory maintenance and compared network connectivity between groups in each memory phase. Mediation analysis was performed to investigate the mediator between β-amyloid and related cognitive performance. Results: Alzheimer's disease was primarily characterized by decreased functional connectivity in a data-driven network composed of an a priori default mode network, limbic network, and frontoparietal network during the memory maintenance (0.205 vs. 0.236, p = 0.04) and retrieval phase (0.159 vs. 0.183, p = 0.017). Within the network, AD had more regions with reduced connectivity during the retrieval than the maintenance and encoding phases (chi-square p = 0.01 and < 0.001). Furthermore, the global cortical β-amyloid negatively correlated with network connectivity during the memory retrieval phase (R = - 0.247, p = 0.032), with this relationship mediating the effect of cortical β-amyloid on memory performance (average causal mediation effect = - 0.05, p = 0.035). Conclusion: We demonstrated that AD had decreased connectivity in specific networks during the memory retrieval phase. Impaired functional connectivity during memory retrieval mediated the adverse effect of β-amyloid on memory. These findings help to elucidate the involvement of cortical β-amyloid (Aβ) in the memory performance in the early stages of AD.

Older Patients with Alzheimer's Disease-Related Cortical Atrophy Who Develop Post-Operative Delirium May Be at Increased Risk of Long-Term Cognitive Decline After Surgery

BACKGROUND

Older surgical patients with Alzheimer's disease (AD) dementia and delirium are at increased risk for accelerated long-term cognitive decline.

OBJECTIVE

Investigate associations between a probabilistic marker of preclinical AD, delirium, and long-term cognitive decline.

METHODS

The Successful Aging after Elective Surgery cohort includes older adults (≥70 years) without dementia who underwent elective surgery. 140 patients underwent preoperative magnetic resonance imaging and had≥6 months cognitive follow-up. Cortical thickness was measured in 'AD-Signature' regions. Delirium was evaluated each postoperative day by the Confusion Assessment Method. Cognitive performance was assessed using a detailed neuropsychological battery at baseline; months 1, 2, and 6; and every 6 months thereafter until 36 months. Using either a General Cognitive Performance composite (GCP) or individual test scores as outcomes, we performed linear mixed effects models to examine main effects of AD-signature atrophy and the interaction of AD-signature atrophy and delirium on slopes of cognitive change from post-operative months 2-36.

RESULTS

Reduced baseline AD-signature cortical thickness was associated with greater 36-month cognitive decline in GCP (standardized beta coefficient, β = -0.030, 95% confidence interval [-0.060, -0.001]). Patients who developed delirium who also had thinner AD signature cortex showed greater decline on a verbal learning test (β = -0.100 [-0.192, -0.007]).

CONCLUSION

Patients with the greatest baseline AD-related cortical atrophy who develop delirium after elective surgery appear to experience the greatest long-term cognitive decline. Thus, atrophy suggestive of preclinical AD and the development of delirium may be high-risk indicators for long-term cognitive decline following surgery.

Differential effects of aging and cognitive decline on visual exploration behavior in the elderly

Visual exploration disturbance has been examined in the elderly, mainly from the perspective of associations with cognitive function. However, it remains unknown whether this is a consequence of cognitive decline, age-related changes independent of cognitive decline, or both. In this study, 15 healthy elderly individuals were evaluated using two figure-matching tasks representing visual information processing (clock-matching and inverted clock-matching tasks). Cognitive functions were evaluated for each subject using the Mini-Mental State Examination (MMSE). Infrared eye-movement assessments were used to analyze eye movements during task performance. Behavioral analyses showed that age was associated with longer reaction time, while MMSE score was associated with higher accuracy on the inverted clock-matching task. Analyses of eye-movement parameters showed that MMSE score was negatively associated with a parameter indicating difficulty in the efficiency of visual exploration planning, while age was tended to be positively associated with the sum of saccade times in each trial, both predominantly on the inverted clock-matching task. Our approaches highlighted that age and cognitive decline are separately associated with eye-movement characteristics: cognitive decline is associated with difficulty in visual exploration planning, particularly in situations that require substantial visual working memory resources, whereas aging may be associated with oculomotor dysfunction.

A new and short protocol to achieve the early diagnosis of mild cognitive impairment

PURPOSE

The mild cognitive impairment (MCI) is a neurocognitive disorder which involves cognitive impairments beyond those expected for the age and education of the subject but are not significant enough to interfere with instrumental activities of daily living. The identification of individuals with MCI is particularly important for those who might benefit from new therapies. The aim of this work is to propose a comprehensive neuropsychological protocol to achieve early diagnosis of MCI.

METHODS

A neuropsychological battery was created and administered to a sample of patients with MCI (n = 25) and healthy matched controls (n = 25).

RESULTS

Although memory decline is often the first sign preceding the appearance of MCI, significant differences in visuospatial tasks, naming abilities, and executive function can be demonstrated as well between MCI and controls.

CONCLUSIONS

A proper selection of cognitive measures within those included in the already-available neuropsychological batteries may provide a thorough assessment of MCI and allow its timely diagnosis.

Elucidating the Risk Factors for Progression from Amyloid-Negative Amnestic Mild Cognitive Impairment to Dementia

BACKGROUND

Amyloid PET allows for the assessment of amyloid β status in the brain, distinguishing true Alzheimer's disease from Alzheimer's disease-mimicking conditions. Around 15-20% of patients with clinically probable Alzheimer's disease have been found to have no significant Alzheimer's pathology on amyloid PET. However, a limited number of studies had been conducted on this subpopulation in terms of clinical progression.

OBJECTIVE

We investigated the risk factors that could affect the progression to dementia in patients with amyloid-negative amnestic mild cognitive impairment (MCI).

METHODS

This study was a single-institutional, retrospective cohort study of patients over the age of 50 with amyloid-negative amnestic MCI who visited the memory clinic of Asan Medical Center with a follow-up period of more than 36 months. All participants underwent brain magnetic resonance imaging (MRI), detailed neuropsychological testing, and fluorine-18[F18]-florbetaben amyloid PET.

RESULTS

During the follow-up period, 39 of 107 patients progressed to dementia from amnestic MCI. In comparison with the stationary group, the progressed group had a more severe impairment in verbal and visual episodic memory function and hippocampal atrophy, which showed an Alzheimer's diseaselike pattern despite the lack of evidence for significant Alzheimer's disease pathology. Voxel-based morphometric MRI analysis revealed that the progressed group had a reduced gray matter volume in the bilateral cerebellar cortices, right temporal cortex, and bilateral insular cortices.

CONCLUSION

Considering the lack of evidence of amyloid pathology, clinical progression of these subpopulation may be caused by other neuropathologies such as TDP-43, abnormal tau or alpha synuclein that lead to neurodegeneration independent of amyloid-driven pathway. Further prospective studies incorporating biomarkers of Alzheimer's disease-mimicking dementia are warranted.

High-Resolution Spectral Sleep Analysis Reveals a Novel Association Between Slow Oscillations and Memory Retention in Elderly Adults

Objective: In recognition of the mixed associations between traditionally scored slow wave sleep and memory, we sought to explore the relationships between slow wave sleep, electroencephalographic (EEG) power spectra during sleep and overnight verbal memory retention in older adults. Design, Setting, Participants, and Measurements: Participants were 101 adults without dementia (52% female, mean age 70.3 years). Delayed verbal memory was first tested in the evening prior to overnight polysomnography (PSG). The following morning, subjects were asked to recall as many items as possible from the same List (overnight memory retention; OMR). Partial correlation analyses examined the associations of delayed verbal memory and OMR with slow wave sleep (SWS) and two physiologic EEG slow wave activity (SWA) power spectral bands (0.5-1 Hz slow oscillations vs. 1-4 Hz delta activity). Results: In subjects displaying SWS, SWS was associated with enhanced delayed verbal memory, but not with OMR. Interestingly, among participants that did not show SWS, OMR was significantly associated with a higher slow oscillation relative power, during NREM sleep in the first ultradian cycle, with medium effect size. Conclusions: These findings suggest a complex relationship between SWS and memory and illustrate that even in the absence of scorable SWS, older adults demonstrate substantial slow wave activity. Further, these slow oscillations (0.5-1 Hz), in the first ultradian cycle, are positively associated with OMR, but only in those without SWS. Our findings raise the possibility that precise features of slow wave activity play key roles in maintaining memory function in healthy aging. Further, our results underscore that conventional methods of sleep evaluation may not be sufficiently sensitive to detect associations between SWA and memory in older adults.

Interventions to Preserve Cognitive Functioning Among Older Kidney Transplant Recipients

PURPOSE OF REVIEW

To summarize the research on effective interventions for preserving cognitive function and prevent cognitive decline in patients with end-stage kidney disease (ESKD) who are undergoing dialysis and/or kidney transplantation (KT).

RECENT FINDINGS

Among ESKD patients undergoing hemodialysis, exercise training has been administered through home-based and intradialytic interventions. Additionally, one pilot study identified intradialytic cognitive training, electronic brain games, as an intervention to preserve cognitive function among patients undergoing hemodialysis. Fewer studies have investigated interventions to preserver cognitive function among KT recipients. To date, the only randomized controlled trial in this population identified B-vitamin supplements as an intervention to preserve cognitive function. The evidence from these trials support a short-term benefit of cognitive and exercise training as well as B-vitamin supplementation among patients with ESKD. Future studies should: 1) replicate these findings, 2) identify interventions specific to KT candidates, and 3) investigate the synergistic impact of both cognitive and exercise training.

SUMMARY

Cognitive prehabilitation, with cognitive and/or exercise training, may be novel interventions for KT candidates that not only reduces delirium risk and long-term post-KT cognitive decline but also prevents dementia.

Brief visuospatial memory test-revised normative data and form equivalency for adults ages 80-89

OBJECTIVE

To provide normative data and examine form equivalency of the Brief Visuospatial Memory Test-Revised (BVMT-R) in a sample of 9^th decade adults. Method: The sample was comprised of 90 healthy individuals ages 80-84 (n = 42) and 85-89 (n = 48). The average years of education was 14.8 (2.4). The BVMT-R Forms 1 and 4 were administered in a counterbalanced order, one week apart. Form equivalency was conducted utilizing Analysis of Variance (ANOVA). Results: There were no significant gender, education, or MMSE differences between the two age groups or between the counterbalanced subgroups. There were no significant differences between Forms 1 and 4 for the 80-84 age group. However, BVMT-R Form 1 Trial 1 and Total Recall raw scores were significantly higher than those for Form 4 in the 85-89 age group. Conclusions: Individuals in their early 80s obtained comparable scores on Forms 1 and 4 of the BVMT-R; however, individuals in their late 80 s showed more difficulty learning and recalling information presented in Form 4 compared to Form 1. It is recommended that clinicians consider form-specific normative data with this population.

Strategic encoding and retrieval processes in verbal recall among middle-aged and older adults

The authors used an analysis of individual differences to examine the role of executive control in strategic encoding and retrieval in verbal recall. Participants enrolled in the Louisiana Healthy Aging Study completed measures of working memory (WM), cognitive status, vocabulary, and free recall of words. Indices of clustering in free recall were calculated to permit inferences on strategic encoding and retrieval processes. We hypothesized that WM would be more strongly associated with strategic encoding and retrieval metrics than vocabulary based on the assumption that successful remembering requires executive control in WM. Regression analyses, together with a variance portioning procedure, confirmed that WM had comparable levels of unique and shared variance with the strategic encoding and retrieval metrics, and both exceeded vocabulary. Theoretical and clinical implications of these data are considered, with the suggestion of future research in lifespan samples as opposed to exclusively young adult or older adult samples.

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).

The influence of age of acquisition on recall and recognition in Alzheimer's patients and healthy ageing controls in Turkish

The current study set out to examine the influence of AoA on word recall and recognition tasks in 30 Alzheimer's patients and 28 healthy ageing control group. Each participant was presented with 20 words that critically varied on AoA. A subtest of WAIS-R was employed to establish the vocabulary capacity of participants together with the Mini-Mental State Examination. The pattern of results showed that healthy ageing adults outperformed Alzheimer's patients in recall and recognition tasks and that overall early acquired words had an advantage over late acquired words. The results have implications for developing assessment tools and are discussed within the current theories of age of acquisition and the impact of the neurodegenerative loss of memory in Alzheimer's disease on lexicosemantic processing.

Semantic Priming in Mild Cognitive Impairment and Healthy Subjects: Effect of Different Time of Presentation of Word-Pairs

INTRODUCTION

Semantic memory is impaired in mild cognitive impairment (MCI). Twomain hypotheses about this finding are debated and refer to the degradation of stored knowledgeversus the impairment of semantic access mechanisms. The aim of our study is to evaluate semanticimpairment in MCI versus healthy subjects (HS) by an experiment evaluating semantic priming.

METHODS

We enrolled 27 MCI and 20 HS. MCI group were divided, according to follow up, intoconverters-MCI and non converters-MCI. The semantic task consisted of 108 pairs of words, 54 ofwhich were semantically associated. Stimuli were presented 250 or 900 ms later the appearance ofthe target in a randomized manner. Data were analyzed using factorial ANOVA.

RESULTS

Both HSand MCI answered more quickly for word than for non-word at both stimulus onset asynchrony(SOA) intervals. At 250 ms, both MCI and HS experienced a shorter time of response for relatedwordthan for unrelated words (priming effect), while only the converters-MCI subgroup lost thepriming effect. Further, we observed a rather larger Cohen's d effect size in non converters-MCIthan in converters-MCI.

CONCLUSION

Our data, and in particular the absence of a semantic primingeffect in converters-MCI, could reflect the impairment of semantic knowledge rather than theaccessibility of semantic stores in MCI individuals that progress to dementia.

The update of semantic memories in amnestic mild cognitive impairment

It is still controversial to what extent neocortical consolidated memories are susceptible of change by processes of reconsolidation and transformation throughout experience, and whether the medial temporal lobes are necessary for this update of semantic consolidated memories, as they are for episodic remembering. We hypothesize that patients with amnestic mild cognitive impairment (aMCI) who have deficits in episodic memory may also have difficulties in updating information on added new features of objects. Sixteen participants with aMCI and 20 healthy control participants performed a semantic word-to-picture task, in which they were asked to identify as belonging to a given semantic category NEW objects, that have incorporated novel features, as well as OLD items, semantically and visually SIMILAR items and UNRELATED items. Patients with aMCI made a greater percentage of errors than healthy controls. Participants globally made greater percentages of errors in difficult types of items, namely NEW and SIMILAR, as compared to easier ones, OLD and UNRELATED. Importantly, an item by diagnostic group interaction effect was observed, and post hoc analysis showed that patients with aMCI made a higher percentage of errors than controls in NEW items only. In conclusion, patients with aMCI had a particular difficulty in identifying the NEW items of the word-to-picture task as compared to the control participants, supporting the concept of a flexible and dynamic conceptual knowledge system, involving the update of semantic memories and the integration of new attributes in a constant transformation process, which is impaired in these patients.

Neuropsychological predictors of cognitive deterioration in non-demented individuals

Introduction: Previous studies performed neuropsychological tests in non-demented patients, especially those with mild cognitive impairment (MCI), to predict dementia. Few recent studies reported that subjective cognitive decline (SCD) itself predicts dementia conversion. We evaluated certain characteristics and neuropsychological tests to predict cognitive deterioration in non-demented individuals.Methods: This study included 106 participants with subjective cognitive complaints (SCCs) classified as non-demented (90 MCI and 16 SCD). Data were collected at baseline and follow-up, wherein participants completed a comprehensive neuropsychological assessment to assess their cognitive and daily functions.Results: During the follow-up of all participants, 52 converted to dementia, while 54 did not. There were significant differences in age and education years, as well as language, memory, frontal lobe function, and Barthel's Activities of Daily Living Index between the groups. Correlation analysis showed a significant correlation between the deterioration of the Clinical Dementia Rating scores and baseline language, memory, and frontal lobe function scores.Conclusion(s): SCDs consistently worrying about their SCCs and those identified with SCD by their caregivers were prone to cognitive function deterioration over time. Changes in language, memory, and frontal lobe function in neurocognitive tests were significantly different between the dementia converters and non dementia converters group. Particularly, SCD and MCI individuals with significantly poor initial executive function and memory abilities should be closely monitored for future cognitive decline.

APOE4 moderates effects of cortical iron on synchronized default mode network activity in cognitively healthy old-aged adults

INTRODUCTION

Apolipoprotein E ε4 (APOE4)-related genetic risk for sporadic Alzheimer's disease is associated with an early impairment of cognitive brain networks. The current study determines relationships between APOE4 carrier status, cortical iron, and cortical network-functionality.

METHODS

Sixty-nine cognitively healthy old-aged individuals (mean age [SD] 66.1 [± 7.2] years; Mini-Mental State Exam [MMSE] 29.3 ± 1.1) were genotyped for APOE4 carrier-status and received 3 Tesla magnetic resonance imaging (MRI) for blood oxygen level-dependent functional magnetic resonance imaging (MRI) at rest, three-dimensional (3D)-gradient echo (six echoes) for cortical gray-matter, non-heme iron by quantitative susceptibility mapping, and 18F-flutemetamol positron emission tomography for amyloid-β.

RESULTS

A spatial pattern consistent with the default mode network (DMN) could be identified by independent component analysis. DMN activity was enhanced in APOE4 carriers and related to cortical iron burden. APOE4 and cortical iron synergistically interacted with DMN activity. Secondary analysis revealed a positive, APOE4 associated, relationship between cortical iron and DMN connectivity.

DISCUSSION

Our findings suggest that APOE4 moderates effects of iron on brain functionality prior to manifestation of cognitive impairment.

The association of a novel cognitive frailty index and physical functioning in older at-risk adults

Objectives: Cognitive frailty is a state at the lower end of the continuum of cognitive resilience in which one is at elevated risk for cognitive impairment and dementia. Metrics of a newly developed Cognitive Frailty Index (CFI) were examined for their association with objective functional limitations.Methods: We used baseline data from 607 participants from the Baltimore Experience Corps Trial with measures on the CFI, a computerized Stroop test, and Short Physical Performance Battery (SPPB) score ≤9. Multivariable log-binomial regression models were used to evaluate the associations of CFI metrics (mean reaction time (RT) for total, first-half and second-half trials per condition) with the SPPB. Latent growth models were used to create additional CFI metrics of initial level (intercept) and change (slope) in RT across accurate trials by easy (Color-X) and difficult (Color-Word) conditions. Models were adjusted for race, sex, age, income, major morbidities, depressive symptoms, self-reported health, and Stroop interference (for Color-Word condition only).Results: All CFI RT metrics were associated with SPPB <9, yet latent growth model approaches were most informative. Initial levels of performance on easy (Risk Ratio, [RR] = 1.24; 95% Confidence Interval, [CI]: 1.03, 1.49) and difficult conditions (RR = 1.22; 95% CI: 1.05, 1.41), not rates of learning (slope) (RR = 1.08, 95% CI: 0.81, 1.45 and RR = 1.11, 95% CI: 0.96, 1.27 respectively), were associated with worse physical functioning.Conclusions: The association between the CFI and physical functioning demonstrates the interplay of cognitive frailty and worse objective mobility within a sociodemographic at-risk sample.

Hippocampal viscoelasticity and episodic memory performance in healthy older adults examined with magnetic resonance elastography

Episodic memory is particularly sensitive to normative aging; however, studies investigating the structure-function relationships that support episodic memory have primarily been limited to gross volumetric measures of brain tissue health. Magnetic resonance elastography (MRE) is an emerging non-invasive, high-resolution imaging technique that uniquely quantifies brain viscoelasticity, and as such, provides a more specific measure of neural microstructural integrity. Recently, a significant double dissociation between orbitofrontal cortex-fluid intelligence and hippocampal-relational memory structure-function relationships was observed in young adults, highlighting the potential of sensitive MRE measures for studying brain health and its relation to cognitive function. However, the structure-function relationship observed by MRE has not yet been explored in healthy older adults. In this study, we examined the relationship between hippocampal (HC) viscoelasticity and episodic memory in cognitively healthy adults aged 66-73 years (N = 11), as measured with the verbal-paired associates (VPA) subtest from the Wechsler Memory Scale (WMS-R). Given the particular dependence of verbal memory tasks on the left HC, unilateral HC MRE measurements were considered for the first time. A significant negative correlation was found between left HC damping ratio, ξ and VPA recall score (r_s = -0.77, p = 0.009), which is consistent with previous findings of a relationship between HC ξ and memory performance in young adults. Conversely, correlations between right HC ξ with VPA recall score were not significant. These results highlight the utility of MRE to study cognitive decline and brain aging and suggest its possible use as a sensitive imaging biomarker for memory-related impairments.

Breadth and depth of working memory and executive function compromises in mild cognitive impairment and their relationships to frontal lobe morphometry and functional competence

INTRODUCTION

The extent of working memory (WM) and executive function (EF) impairment in mild cognitive impairment (MCI) is not well-characterized.

METHODS

We compared 48 patients with MCI, 124 noncognitively impaired elderly healthy controls, and 57 patients with Alzheimer's disease (AD) on multiple WM/EF measures, frontal lobe integrity indexes, and functioning.

RESULTS

Patients with MCI demonstrated worse performance on nearly all WM/EF tests. This profile of impairment was refined in a factor analysis that identified three primary WM/EF constructs: WM storage; speed and controlled visual search; and manipulation of information and problem solving. EF impairments were associated with reductions in prefrontal cortical thickness. WM/EF accounted for over 50% of the variance in functional competence.

DISCUSSION

In MCI, WM/EF impairments are far from rare, based on specific compromises to frontal cortex circuitry, and are associated with loss of everyday functioning. WM/EF impairments, even at this potentially prodromal stage of AD, have clinically deleterious consequences.

Assessment of Memory Impairment in Early Diagnosis of Alzheimer's Disease

Memory impairment has been considered as one of the earliest clinical hallmarks of Alzheimer's disease. This paper summarizes recent progress in the assessment of memory impairment in predementia stages. New promising approaches of memory assessment include evaluation of longitudinal cognitive changes, assessment of long-term memory loss, evaluation of subjective cognitive concerns and testing of other memory modalities, such as spatial memory. In addition, we describe new challenging memory tests based on memory binding paradigms that have been recently developed and are currently being validated.

NeuroBel: Spanish screening test for oral psycholinguistics disabilities in elderly people with mild cognitive impairment and early-stage Alzheimer's disease

INTRODUCTION

The NeuroBel is a short test that allows for psycholinguistic assessment of basic processes of oral comprehension and language production deterioration in the elderly. The objective is to carry out a pilot study of the initial reference values and cut-off points of this battery using a sample of Spanish elderly adults, with and without cognitive impairment, and detecting performance differences among them.

METHOD

NeuroBel consists of 8 tasks that analyze oral language functioning from the theoretical model proposed by the Psycholinguistic approach. Seventy-five Spanish monolingual adult-elderly participants of both genders. Of those, 25 with Alzheimer's disease (AD) in the initial phase, 25 with mild cognitive impairment (MCI) and 25 participants without cognitive impairment (Controls). All subjects were evaluated using NeuroBel.

RESULTS

There are significant differences between the three groups. The participants with AD are significantly worse in the total score of NeuroBel. A discriminant analysis shows that 86.7% of the cases appear correctly classified in the groups originally selected. Likewise, participants with MCI obtained results that are statistically significantly worse than the control group. NeuroBel shows a high correlation with the MMSE (.89) and Sensitivity (.96) in the determination of AD and cognitive deterioration (AD + MCI vs. Controls). The area under the ROC curve is .97 in the contrast of AD vs. Controls and .98 in the determination of cognitive deterioration (AD + MCI vs. Controls). The canonical discriminant functions and the precision cut-offs from the ROC analyses are also shown in the results.

CONCLUSIONS

NeuroBel is shown as a "very good" test in the detection of cognitive-linguistic impairment in elderly-adults.

Cognitive trajectories in relapsing-remitting multiple sclerosis: A longitudinal 6-year study

BACKGROUND

Information concerning longitudinal cognitive trajectories in multiple sclerosis (MS) is relatively scarce. Moreover, it is unclear which factors are associated with cognitive decline and what is the clinical impact of cognitive impairment (CI) in the long run.

OBJECTIVE

To investigate cognitive trajectories in relapsing-remitting multiple sclerosis (RRMS) patients, analyzing clinical and magnetic resonance imaging (MRI) predictors of cognitive decline.

METHODS

We enrolled 42 patients and 30 controls. They underwent brain MRI and clinical/neuropsychological evaluation at baseline and after 1, 2, and 6 years. We evaluated cognitive domains with principal component analysis and performed multivariable regression analyzing predictors of clinical/cognitive deterioration. We also performed repeated measures analysis to assess whether clinical progression was different according to CI at baseline.

RESULTS

A total of 23 (62.2%) patients deteriorated in combined cognitive domains after 6 years, most in processing speed and memory. The number of baseline impaired cognitive domains was strongly associated with 6-year cognitive (R² = 0.452; p < 0.001) and Expanded Disability Status Scale (EDSS) deterioration (R² = 0.263; p < 0.001). Patients with baseline CI in combined domains had worse clinical progression.

CONCLUSION

Isolated CI tends to become more widespread, affecting memory and processing speed alongside. The extent of baseline CI was the best predictor of both clinical and cognitive deterioration after 6 years.