Preclinical prediction of AD using neuropsychological tests

Retrieval Deficiency in Brain Activity of Working Memory in Amnesic Mild Cognitive Impairment Patients: A Brain Event-Related Potentials Study

In the early stage of Alzheimer disease (AD) or mild cognitive impairment (MCI), working memory (WM) deficiency is prominent and could be attributed to failure in encoding, maintenance or retrieval of information. However, evidence for a retention or retrieval deficit remains equivocal. It is also unclear what cognitive mechanism in WM is impaired in MCI or early AD. We enrolled 46 subjects from our Memory Clinics and community, with 24 amnesic MCI patients and 22 normal subjects. After neurological and cognitive assessments, they performed a classic delayed match to sample (DMS) task with simultaneous event-related potential (ERP) recorded. The ERPs in encoding and retrieval epoch during WM were analyzed separately. The latency and amplitude of every ERP component were compared between two groups, and then analyzed to explore their relationship with neuropsychological performance. Finally, the locations of maximal difference in cortex were calculated by standard low-resolution tomographic analysis. A total of five components were found: P1, N1, P2, N2, and P300. The amplitude of P2 and P300 was larger in normal subjects than in MCI patients only during retrieval, not encoding epoch, while the latency did not show statistical difference. The latency and amplitude of P1 and N1 were similar in two groups. P2 amplitude in the retrieval epoch positively correlated with memory test (auditory verbal learning test) and visual spatial score of Chinese Addenbrooke's Cognitive Examination-Revised (ACE-R), while P300 amplitude correlated with ACE-R. The activation difference in P2 time range was maximal at medial frontal gyrus. However, the difference in cortex activation during P300 time range did not show significance. The amplitude of P2 indicated deficiency in memory retrieval process, potentially due to dysfunction of central executive in WM model. Regarding the location of P2 during WM task, medial frontal plays important role in memory retrieval. The findings in the present study suggested that MCI patients have retrieval deficit, probably due to central executive based on medial frontal gyrus. Thus, it may provide new biomarker for early detection and intervention for aMCI.

Neuropsychological tests for predicting cognitive decline in older adults

AIM

To determine neuropsychological tests likely to predict cognitive decline.

METHODS

A sample of nonconverters (n = 106) was compared with those who declined in cognitive status (n = 24). Significant univariate logistic regression prediction models were used to create multivariate logistic regression models to predict decline based on initial neuropsychological testing.

RESULTS

Rey-Osterrieth Complex Figure Test (RCFT) Retention predicted conversion to mild cognitive impairment (MCI) while baseline Buschke Delay predicted conversion to Alzheimer's disease (AD). Due to group sample size differences, additional analyses were conducted using a subsample of demographically matched nonconverters. Analyses indicated RCFT Retention predicted conversion to MCI and AD, and Buschke Delay predicted conversion to AD.

CONCLUSION

Results suggest RCFT Retention and Buschke Delay may be useful in predicting cognitive decline.

Inclusion of an informant yields strong associations between cognitive complaint and longitudinal cognitive outcomes in non-demented elders

BACKGROUND

The relation between the source of cognitive complaint and objective cognitive performance is not well understood.

OBJECTIVE

Examine self and informant cognitive complaint as predictors of objective cognitive and functional trajectory in non-demented elders.

METHODS

Participants from the National Alzheimer's Coordinating Center had a baseline diagnosis of normal cognition (NC; n = 6133, 72±8 years, 68% female) or mild cognitive impairment (MCI; n = 3010, 74±8 years, 55% female). Four independent groups defined cognitive complaint: no complaint, self-only complaint, informant-only complaint, or mutual complaint (both self and informant complaint). Linear mixed model regression analyses related complaint status (referent was no complaint) to cognitive and functional trajectories, adjusting for age, sex, race, education, and follow-up period.

RESULTS

Among NC participants, mutual complaint related to faster decline in global cognition (p < 0.0001), language (all p-values <0.0001), processing speed (p = 0.0002), and executive functioning (p = 0.0006). Informant-only complaint related to faster decline in global cognition (p = 0.0001) and processing speed (p = 0.0001). Self-only complaint related to greater decline in immediate (p < 0.0001) and delayed (p = 0.0005) episodic memory. In MCI, mutual complaint related to faster decline in global cognition (p < 0.0001), verbal episodic memory (all p-values <0.0001), language (all p-values <0.0001), and processing speed(all p-values <0.0006). Informant-only or self-only complaint associations with cognitive trajectory did not survive correction factor for multiple comparisons.Conclusion: Cognitive complaint appears to have clinical significance, as it is related to declines in objective cognitive performance over time. Mutual complaint was associated with the worst cognitive trajectory in both NC and MCI elders, highlighting the importance of incorporating an informant into evaluation of elders whenever feasible.

Understanding the cognitive underpinnings of functional impairments in early dementia: a review

OBJECTIVES

Early dementia is marked by cognitive and functional impairments, and although studies indicate an association between these, detailed analyses exploring this relationship are rare. It is crucial to understand how specific cognitive deficits underlie functional deficits to develop successful cognitive interventions. This paper reviews the evidence of impairment in everyday functioning and in working, long-term and prospective memory in early dementia. Findings are evaluated with respect to the relationship between cognitive and functional impairments.

METHODS

From the literature searches, 17 studies on everyday functioning and 40 studies on memory were obtained. Studies were only included if patients had an official diagnosis and were in the early stages of dementia.

RESULTS

Complex instrumental activities of daily living were subject to greater impairment than basic activities of daily living. In particular, early dementia patients struggle with finance tasks; a deficit linked to impaired working memory. Regarding cognition, long-term memory is the earliest form of memory to decline as is well recognised. Evidence also indicates deficits in working and prospective memory, with inconsistent evidence about impairments of the former. A major limitation of the literature is a lack of studies assessing individual everyday activities and the associated error patterns that might occur.

CONCLUSION

This review critically assesses the status of translational research for everyday activities in early dementia, an area with critical implications for cognitive-based rehabilitation. Further research is required into the detailed assessment of individual everyday activity and specific memory deficits, in order to effectively map cognitive functions onto functional performance.

Early-onset and late-onset Alzheimer's disease are associated with distinct patterns of memory impairment

The goal of this study was to investigate the specific patterns of memory breakdown in patients suffering from early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD). Twenty EOAD patients, twenty LOAD patients, twenty matched younger controls, and twenty matched older controls participated in this study. All participants underwent a detailed neuropsychological assessment, an MRI scan, an FDG-PET scan, and AD patients had biomarkers as supporting evidence of both amyloïdopathy and neuronal injury. Results of the neuropsychological assessment showed that both EOAD and LOAD groups were impaired in the domains of memory, executive functions, language, praxis, and visuoconstructional abilities, when compared to their respective control groups. EOAD and LOAD groups, however, showed distinct patterns of memory impairment. Even though both groups were similarly affected on measures of episodic, short term and working memory, in contrast semantic memory was significantly more impaired in LOAD than in EOAD patients. The EOAD group was not more affected than the LOAD group in any memory domain. EOAD patients, however, showed significantly poorer performance in other cognitive domains including executive functions and visuoconstructional abilities. A more detailed analysis of the pattern of semantic memory performance among patient groups revealed that the LOAD was more profoundly impaired, in tasks of both spontaneous recall and semantic recognition. Voxel-Based Morphometry (VBM) analyses showed that impaired semantic performance in patients was associated with reduced gray matter volume in the anterior temporal lobe (ATL) region, while PET-FDG analyses revealed that poorer semantic performance was associated with greater hypometabolism in the left temporoparietal region, both areas reflecting key regions of the semantic network. Results of this study indicate that EOAD and LOAD patients present with distinct patterns of memory impairment, and that a genuine semantic impairment may represent one of the clinical hallmarks of LOAD.

Aerobic and Cognitive Exercise (ACE) Pilot Study for Older Adults: Executive Function Improves with Cognitive Challenge While Exergaming

Dementia cases are increasing worldwide; thus, investigators seek to identify interventions that might prevent or ameliorate cognitive decline in later life. Extensive research confirms the benefits of physical exercise for brain health, yet only a fraction of older adults exercise regularly. Interactive mental and physical exercise, as in aerobic exergaming, not only motivates, but has also been found to yield cognitive benefit above and beyond traditional exercise. This pilot study sought to investigate whether greater cognitive challenge while exergaming would yield differential outcomes in executive function and generalize to everyday functioning. Sixty-four community based older adults (mean age=82) were randomly assigned to pedal a stationary bike, while interactively engaging on-screen with: (1) a low cognitive demand task (bike tour), or (2) a high cognitive demand task (video game). Executive function (indices from Trails, Stroop and Digit Span) was assessed before and after a single-bout and 3-month exercise intervention. Significant group × time interactions were found after a single-bout (Color Trails) and after 3 months of exergaming (Stroop; among 20 adherents). Those in the high cognitive demand group performed better than those in the low cognitive dose condition. Everyday function improved across both exercise conditions. Pilot data indicate that for older adults, cognitive benefit while exergaming increased concomitantly with higher doses of interactive mental challenge.

Subjective memory complaint only relates to verbal episodic memory performance in mild cognitive impairment

BACKGROUND

A cognitive concern from the patient, informant, or clinician is required for the diagnosis of mild cognitive impairment (MCI); however, the cognitive and neuroanatomical correlates of complaint are poorly understood.

OBJECTIVE

We assessed how self-complaint relates to cognitive and neuroimaging measures in older adults with MCI.

METHOD

MCI participants were drawn from the Alzheimer's Disease Neuroimaging Initiative and dichotomized into two groups based on the presence of self-reported memory complaint (no complaint n = 191, 77 ± 7 years; complaint n = 206, 73 ± 8 years). Cognitive outcomes included episodic memory, executive functioning, information processing speed, and language. Imaging outcomes included regional lobar volumes (frontal, parietal, temporal, cingulate) and specific medial temporal lobe structures (hippocampal volume, entorhinal cortex thickness, parahippocampal gyrus thickness).

RESULTS

Linear regressions, adjusting for age, gender, race, education, Mini-Mental State Examination score, mood, and apolipoprotein E4 status, found that cognitive complaint related to immediate (β = -1.07, p < 0.001) and delayed episodic memory performances assessed on a serial list learning task (β = -1.06, p = 0.001) but no other cognitive measures or neuroimaging markers.

CONCLUSIONS

Self-reported memory concern was unrelated to structural neuroimaging markers of atrophy and measures of information processing speed, executive functioning, or language. In contrast, subjective memory complaint related to objective verbal episodic learning performance. Future research is warranted to better understand the relation between cognitive complaint and surrogate markers of abnormal brain aging, including Alzheimer's disease, across the cognitive aging spectrum.

Associations between Verbal Learning Slope and Neuroimaging Markers across the Cognitive Aging Spectrum

A symptom of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is a flat learning profile. Learning slope calculation methods vary, and the optimal method for capturing neuroanatomical changes associated with MCI and early AD pathology is unclear. This study cross-sectionally compared four different learning slope measures from the Rey Auditory Verbal Learning Test (simple slope, regression-based slope, two-slope method, peak slope) to structural neuroimaging markers of early AD neurodegeneration (hippocampal volume, cortical thickness in parahippocampal gyrus, precuneus, and lateral prefrontal cortex) across the cognitive aging spectrum [normal control (NC); (n=198; age=76±5), MCI (n=370; age=75±7), and AD (n=171; age=76±7)] in ADNI. Within diagnostic group, general linear models related slope methods individually to neuroimaging variables, adjusting for age, sex, education, and APOE4 status. Among MCI, better learning performance on simple slope, regression-based slope, and late slope (Trial 2-5) from the two-slope method related to larger parahippocampal thickness (all p-values<.01) and hippocampal volume (p<.01). Better regression-based slope (p<.01) and late slope (p<.01) were related to larger ventrolateral prefrontal cortex in MCI. No significant associations emerged between any slope and neuroimaging variables for NC (p-values ≥.05) or AD (p-values ≥.02). Better learning performances related to larger medial temporal lobe (i.e., hippocampal volume, parahippocampal gyrus thickness) and ventrolateral prefrontal cortex in MCI only. Regression-based and late slope were most highly correlated with neuroimaging markers and explained more variance above and beyond other common memory indices, such as total learning. Simple slope may offer an acceptable alternative given its ease of calculation.

Behavioral abnormalities in APPSwe/PS1dE9 mouse model of AD-like pathology: comparative analysis across multiple behavioral domains

Alzheimer's disease (AD) is characterized by dysfunction in cognitive and noncognitive domains with clinical diagnosis based on multiple neuropsychological tests. Here, we evaluated cognitive and noncognitive behaviors in 2 age cohorts (8 and 14 months at the start of the study) of APPSwe/PS1dE9 transgenic mice that model AD-like amyloidosis. We used a battery of tests that included fear-conditioned context and tone memories, swimming activity, and orientation to a proximal cue in a visible platform water maze test and burrowing and nest building activity. To compare the performance of mice across all tests, we used z-score normalization of data. The analyses revealed that the behavior of the transgenic mice was significantly compromised in cognitive as well as in noncognitive domains. Combining scores across multiple behavioral tests produced an integrated index characterizing the overall phenotypic abnormality in this model of AD-like amyloidosis. Assessing multiple behavioral domains provides a broader view of the breadth of impairments in multiple behavioral systems. Greater implementation of such approaches could enable reliable and clinically predictive evaluation of therapeutics in mouse models of amyloidosis.

Task-evoked fMRI changes in attention networks are associated with preclinical Alzheimer's disease biomarkers

There is a growing emphasis on examining preclinical levels of Alzheimer's disease (AD)-related pathology in the absence of cognitive impairment. Previous work examining biomarkers has focused almost exclusively on memory, although there is mounting evidence that attention also declines early in disease progression. In the current experiment, 2 attentional control tasks were used to examine alterations in task-evoked functional magnetic resonance imaging data related to biomarkers of AD pathology. Seventy-one cognitively normal individuals (females = 44, mean age = 63.5 years) performed 2 attention-demanding cognitive tasks in a design that modeled both trial- and task-level functional magnetic resonance imaging changes. Biomarkers included amyloid β42, tau, and phosphorylated tau measured from cerebrospinal fluid and positron emission tomography measures of amyloid deposition. Both tasks elicited widespread patterns of activation and deactivation associated with large task-level manipulations of attention. Importantly, results from both tasks indicated that higher levels of tau and phosphorylated tau pathologies were associated with block-level overactivations of attentional control areas. This suggests early alteration in attentional control with rising levels of AD pathology.

The trajectory of cognitive decline in the pre-dementia phase in memory clinic visitors: findings from the 4C-MCI study

BACKGROUND

We investigated the course of decline in multiple cognitive domains in non-demented subjects from a memory clinic setting, and compared pattern, onset and magnitude of decline between subjects who progressed to Alzheimer's disease (AD) dementia at follow-up and subjects who did not progress.

METHOD

In this retrospective cohort study 819 consecutive non-demented patients who visited the memory clinics in Maastricht or Amsterdam between 1987 and 2010 were followed until they became demented or for a maximum of 10 years (range 0.5-10 years). Differences in trajectories of episodic memory, executive functioning, verbal fluency, and information processing speed/attention between converters to AD dementia and subjects remaining non-demented were compared by means of random effects modelling.

RESULTS

The cognitive performance of converters and non-converters could already be differentiated seven (episodic memory) to three (verbal fluency and executive functioning) years prior to dementia diagnosis. Converters declined in these three domains, while non-converters remained stable on episodic memory and executive functioning and showed modest decline in verbal fluency. There was no evidence of decline in information processing speed/attention in either group.

CONCLUSIONS

Differences in cognitive performance between converters to AD dementia and subjects remaining non-demented could be established 7 years prior to diagnosis for episodic memory, with verbal fluency and executive functioning following several years later. Therefore, in addition to early episodic memory decline, decline in executive functions may also flag incident AD dementia. By contrast, change in information processing speed/attention seems less informative.

A study on the specificity of the association between hippocampal volume and delayed primacy performance in cognitively intact elderly individuals

Delayed recall at the primacy position (first few items on a list) has been shown to predict cognitive decline in cognitively intact elderly participants, with poorer delayed primacy performance associated with more pronounced generalized cognitive decline during follow-up. We have previously suggested that this association is due to delayed primacy performance indexing memory consolidation, which in turn is thought to depend upon hippocampal function. Here, we test the hypothesis that hippocampal size is associated with delayed primacy performance in cognitively intact elderly individuals. Data were analyzed from a group (N=81) of cognitively intact participants, aged 60 or above. Serial position performance was measured with the Buschke selective reminding test (BSRT). Hippocampal size was automatically measured via MRI, and unbiased voxel-based analyses were also conducted to explore further regional specificity of memory performance. We conducted regression analyses of hippocampus volumes on serial position performance; other predictors included age, family history of Alzheimer's disease (AD), APOE ε4 status, education, and total intracranial volume. Our results collectively suggest that there is a preferential association between hippocampal volume and delayed primacy performance. These findings are consistent with the hypothesis that delayed primacy consolidation is associated with hippocampal size, and shed light on the relationship between delayed primacy performance and generalized cognitive decline in cognitively intact individuals, suggesting that delayed primacy consolidation may serve as a sensitive marker of hippocampal health in these individuals.

Three midlife strategies to prevent cognitive impairment due to Alzheimer's disease

The slow, progressive accumulation of pathology characteristic of Alzheimer's disease is the principal determinant of cognitive decline leading to dementia. Risk-reduction strategies during midlife focus on raising the clinical threshold for the appearance of cognitive symptoms and on reducing the extent of Alzheimer pathology. Best available evidence suggests an approach based on three, conceptually distinct strategies. (1) Raise the threshold for cognitive symptoms by improving brain health. To achieve this goal, the tactic is to reduce cerebrovascular risks mediated by hypertension, diabetes, cigarette smoking, and hyperlipidemia. (2) Raise the threshold for cognitive symptoms by enhancing cognitive reserve. Here, tactics focus on mental stimulation associated with occupation, leisure activities and social engagement. (3) Reduce the burden of Alzheimer pathology. The most promising tactic toward this end is regular aerobic exercise. Tactics in support of strategies to reduce cognitive impairment due to Alzheimer pathology are not yet substantiated by robust, consistent clinical trial evidence. There is pressing need for well-designed pragmatic trials to provide stronger evidence on preventive strategies for late-life cognitive decline and dementia.

Validation of a self-administered computerized system to detect cognitive impairment in older adults

There is increasing interest in the development of economical and accurate approaches to identifying persons in the community who have mild, undetected cognitive impairments. Computerized assessment systems have been suggested as a viable approach to identifying these persons. The validity of a computerized assessment system for identification of memory and executive deficits in older individuals was evaluated in the current study. Volunteers (N = 235) completed a 3-hr battery of neuropsychological tests and a computerized cognitive assessment system. Participants were classified as impaired (n = 78) or unimpaired (n = 157) on the basis of the Mini Mental State Exam, Wechsler Memory Scale-III and the Trail Making Test (TMT), Part B. All six variables (three memory variables and three executive variables) derived from the computerized assessment differed significantly between groups in the expected direction. There was also evidence of temporal stability and concurrent validity. Application of computerized assessment systems for clinical practice and for identification of research participants is discussed in this article.

Delay and probability discounting as candidate markers for dementia: an initial investigation

The present study investigated delay discounting and probability discounting-behavioral economic indices of impulsivity and risk proneness, respectively-in 39 healthy older adults and 25 older adults with mild cognitive impairment (MCI). Relative to the healthy group, it was hypothesized that older adults with MCI would display greater levels of impulsivity, risk proneness, and response inconsistency. The MCI group was found to display a unique delay discounting profile characterized by increasing impulsivity with decreasing reward magnitude, such that cognitively impaired older adults were significantly more impulsive than healthy controls at the small reward magnitude. The two groups exhibited similar levels of probability discounting, though older adults with MCI were significantly less consistent in their risk preferences. The present findings shed light onto decision-making in pre-dementia disease stages and suggest that discounting performance holds potential to complement early diagnostic instruments, likely due to pathophysiological processes in relevant brain regions.

Treatment effects in multiple cognitive domains in Alzheimer's disease: a two-year cohort study

Introduction

Despite widespread use of second-generation cholinesterase inhibitors for the symptomatic treatment of Alzheimer’s disease (AD), little is known about the long term effects of cholinergic treatment on global cognitive function and potential specific effects in different cognitive domains. The objectives of this study were to determine the association between cholinergic treatment and global cognitive function over one and two years in a cohort of patients with mild or moderate AD and identify potential differences in domain-specific cognitive outcomes within this cohort.

Methods

A cohort of patients meeting the revised National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria for mild or moderate AD, including patients both on treatment with a cholinesterase inhibitor and untreated controls (treated = 65, untreated = 65), were recruited from the Cognitive Neurology Clinic at Sunnybrook Health Sciences Centre, as part of the Sunnybrook Dementia Study. Patients were followed for one to two years and underwent standardized neuropsychological assessments to evaluate global and domain-specific cognitive function. Associations between cholinesterase inhibitor use and global and domain-specific cognitive outcome measures at one and two years of follow-up were estimated using mixed model linear regression, adjusting for age, education, and baseline mini mental state examination (MMSE).

Results

At one year, treated patients showed significantly less decline in global cognitive function, and treatment and time effects across tests of executive and visuospatial function. At two years, there was a significant trend towards less decline in global cognition for treated patients. Moreover, treated patients showed significant treatment and time effects across tests of executive functioning, memory, and visuospatial function.

Conclusions

The present study offers two important contributions to knowledge of the effectiveness of cholinesterase inhibitor treatment in patients with mild-moderate AD: 1) that second-generation cholinesterase inhibitors demonstrate long-term effectiveness for reducing global cognitive decline over one to two years of follow-up, and 2) that decline in function for cognitive domains, including executive function, memory, and visuospatial skill that are primarily mediated by frontal networks and by the cholinergic system, rather than memory, may be slowed by treatment targeting the cholinergic system.

Trajectories of Alzheimer disease-related cognitive measures in a longitudinal sample

BACKGROUND

The delineation of the relative temporal trajectories of specific cognitive measures associated with Alzheimer's disease (AD) is important for evaluating preclinical markers and monitoring disease progression.

METHODS

We characterized the temporal trajectories of measures of verbal episodic memory, short-term visual memory, and mental status using data from 895 participants in the Baltimore Longitudinal Study of Aging.

RESULTS

The California Verbal Learning Test (CVLT) immediate recall was the first measure to decline, followed by CVLT delayed recall. However, further along the disease progression scale, CVLT delayed recall and visual memory changed more rapidly than CVLT immediate recall.

CONCLUSIONS

Our findings reconcile reports of early changes in immediate recall with greater reliance on delayed recall performance in clinical settings. Moreover, the utility of cognitive markers in evaluating AD progression depends on the stage of cognitive decline, suggesting that optimal endpoints in therapeutic trials may vary across different stages of the disease process.

Perforant path synaptic loss correlates with cognitive impairment and Alzheimer's disease in the oldest-old

Alzheimer's disease, which is defined pathologically by abundant amyloid plaques and neurofibrillary tangles concurrent with synaptic and neuronal loss, is the most common underlying cause of dementia in the elderly. Among the oldest-old, those aged 90 and older, other ageing-related brain pathologies are prevalent in addition to Alzheimer's disease, including cerebrovascular disease and hippocampal sclerosis. Although definite Alzheimer's disease pathology can distinguish dementia from normal individuals, the pathologies underlying cognitive impairment, especially in the oldest-old, remain poorly understood. We therefore conducted studies to determine the relative contributions of Alzheimer's disease pathology, cerebrovascular disease, hippocampal sclerosis and the altered expression of three synaptic proteins to cognitive status and global cognitive function. Relative immunohistochemistry intensity measures were obtained for synaptophysin, Synaptic vesicle transporter Sv2 (now known as SV2A) and Vesicular glutamate transporter 1 in the outer molecular layer of the hippocampal dentate gyrus on the first 157 participants of 'The 90+ Study' who came to autopsy, including participants with dementia (n = 84), those with cognitive impairment but no dementia (n = 37) and those with normal cognition (n = 36). Thal phase, Braak stage, cerebrovascular disease, hippocampal sclerosis and Pathological 43-kDa transactive response sequence DNA-binding protein (TDP-43) were also analysed. All measures were obtained blind to cognitive diagnosis. Global cognition was tested by the Mini-Mental State Examinaton. Logistic regression analysis explored the association between the pathological measures and the odds of being in the different cognitive groups whereas multiple regression analyses explored the association between pathological measures and global cognition scores. No measure clearly distinguished the control and cognitive impairment groups. Comparing the cognitive impairment and dementia groups, synaptophysin and SV2 were reduced, whereas Braak stage, TDP-43 and hippocampal sclerosis frequency increased. Thal phase and VGLUT1 did not distinguish the cognitive impairment and dementia groups. All measures distinguished the dementia and control groups and all markers associated with the cognitive test scores. When all markers were analysed simultaneously, a reduction in synaptophysin, a high Braak stage and the presence of TDP-43 and hippocampal sclerosis associated with global cognitive function. These findings suggest that tangle pathology, hippocampal sclerosis, TDP-43 and perforant pathway synaptic loss are the major contributors to dementia in the oldest-old. Although an increase in plaque pathology and glutamatergic synaptic loss may be early events associated with cognitive impairment, we conclude that those with cognitive impairment, but no dementia, are indistinguishable from cognitively normal subjects based on the measures reported here.

Mild traumatic brain injury in older adults: early cognitive outcome

Severe traumatic brain injury (TBI) in older age is associated with high rates of mortality. However, little is known about outcome following mild TBI (mTBI) in older age. We report on a prospective cohort study investigating 3 month outcome in older age patients admitted to hospital-based trauma services. First, 50 mTBI older age patients and 58 orthopedic controls were compared to 123 community control participants to evaluate predisposition and general trauma effects on cognition. Specific brain injury effects were subsequently evaluated by comparing the orthopedic control and mTBI groups. Both trauma groups had significantly lower performances than the community group on prospective memory (d=0.82 to 1.18), attention set-shifting (d=-0.61 to -0.69), and physical quality of life measures (d=0.67 to 0.84). However, there was only a small to moderate but non-significant difference in the orthopedic control and mTBI group performances on the most demanding task of prospective memory (d=0.37). These findings indicate that, at 3 months following mTBI, older adults are at risk of poor cognitive performance but this is substantially accounted for by predisposition to injury or general multi-system trauma.

Automatic ROI selection in structural brain MRI using SOM 3D projection

This paper presents a method for selecting Regions of Interest (ROI) in brain Magnetic Resonance Imaging (MRI) for diagnostic purposes, using statistical learning and vector quantization techniques. The proposed method models the distribution of GM and WM tissues grouping the voxels belonging to each tissue in ROIs associated to a specific neurological disorder. Tissue distribution of normal and abnormal images is modelled by a Self-Organizing map (SOM), generating a set of representative prototypes, and the receptive field (RF) of each SOM prototype defines a ROI. Moreover, the proposed method computes the relative importance of each ROI by means of its discriminative power. The devised method has been assessed using 818 images from the Alzheimer's disease Neuroimaging Initiative (ADNI) which were previously segmented through Statistical Parametric Mapping (SPM). The proposed algorithm was used over these images to parcel ROIs associated to the Alzheimer's Disease (AD). Additionally, this method can be used to extract a reduced set of discriminative features for classification, since it compresses discriminative information contained in the brain. Voxels marked by ROIs which were computed using the proposed method, yield classification results up to 90% of accuracy for controls (CN) and Alzheimer's disease (AD) patients, and 84% of accuracy for Mild Cognitive Impairment (MCI) and AD patients.

The "Alzheimer's type" profile of semantic clustering in amnestic mild cognitive impairment

Impairments in learning and recall have been well established in amnestic mild cognitive impairment (aMCI). However, a relative dearth of studies has examined the profiles of memory strategy use in persons with aMCI relative to those with Alzheimer's disease (AD). Participants with aMCI, nonamnestic MCI, AD, and healthy older adults were administered the California Verbal Learning Test-II (CVLT-II). Measures of semantic clustering and recall were obtained across learning and delayed recall trials. In addition, we investigated whether deficits in semantic clustering were related to progression from healthy aging to aMCI and from aMCI to AD. The aMCI group displayed similar semantic clustering performance as the AD participants, whereas the AD group showed greater impairments on recall relative to the aMCI participants. Control participants who progressed to aMCI showed reduced semantic clustering at the short delay at baseline compared to individuals who remained diagnostically stable across follow-up visits. These findings show that the ability to engage in an effective memory strategy is compromised in aMCI, before AD has developed, suggesting that disruptions in semantic networks are an early marker of the disease. (JINS, 2014, 20, 1-11).

Improved design of prodromal Alzheimer's disease trials through cohort enrichment and surrogate endpoints

Alzheimer's disease (AD) trials initiated during or before the prodrome are costly and lengthy because patients are enrolled long before clinical symptoms are apparent, when disease progression is slow. We hypothesized that design of such trials could be improved by: 1) selecting individuals at moderate near-term risk of progression to AD dementia (the current clinical standard) and 2) by using short-term surrogate endpoints that predict progression to AD dementia. We used a longitudinal cohort of older, initially non-demented, community-dwelling participants (n = 358) to derive selection criteria and surrogate endpoints and tested them in an independent national data set (n = 6,243). To identify a "mid-risk" subgroup, we applied conditional tree-based survival models to Clinical Dementia Rating (CDR) scale scores and common neuropsychological tests. In the validation cohort, a time-to-AD dementia trial applying these mid-risk selection criteria to a pool of all non-demented individuals could achieve equivalent power with 47% fewer participants than enrolling at random from that pool. We evaluated surrogate endpoints measureable over two years of follow-up based on cross-validated concordance between predictions from Cox models and observed time to AD dementia. The best performing surrogate, rate of change in CDR sum-of-boxes, did not reduce the trial duration required for equivalent power using estimates from the validation cohort, but alternative surrogates with better ability to predict time to AD dementia should be able to do so. The approach tested here might improve efficiency of prodromal AD trials using other potential measures and could be generalized to other diseases with long prodromal phases.

Cognitive rehabilitation of memory for mild cognitive impairment: a methodological review and model for future research

Several recent reviews have suggested that cognitive rehabilitation may hold promise in the treatment of memory deficits experienced by patients with mild cognitive impairment. In contrast to the previous reviews that mainly focused on outcome, the current review examines key methodological challenges that are critical for designing and interpreting research studies and translating results into clinical practice. Using methodological details from 36 studies, we first examine diagnostic variability and how the use of cutoffs may bias samples toward more severely impaired patients. Second, the strengths and limitations of several common rehabilitative techniques are discussed. Half of the reviewed studies used a multi-technique approach that precludes the causal attribution between any specific technique and subsequent improvement. Third, there is a clear need to examine the dose-response relationship since this information was strikingly absent from most studies. Fourth, outcome measures varied widely and frequently depended on neuropsychological tests with little theoretical justification or ecological relevance. Fifth, we discuss how the variability in each of these other four areas complicates efforts to examine training generalization. Overall, future studies should place greater emphasis on ecologically relevant treatment approaches and outcome measures and we propose a hierarchical model that may aid in this pursuit.

Higher working memory predicts slower functional decline in autopsy-confirmed Alzheimer's disease

BACKGROUND

There is heterogeneity in the pattern of early cognitive deficits in Alzheimer's disease (AD). However, whether the severity of initial cognitive deficits relates to different clinical trajectories of AD progression is unclear.

OBJECTIVE

To determine if deficits in specific cognitive domains at the initial visit relate to the rate of progression in clinical trajectories of AD dementia.

METHODS

68 subjects from the National Alzheimer's Coordinating Center database who had autopsy-confirmed AD as the primary diagnosis and at least 3 serial assessments a year apart, with a Mini-Mental State Examination (MMSE) score >15 and a Clinical Dementia Rating Scale-Global (CDR-G) score ≤1 at the initial visit were included. A mixed regression model was used to examine the association between initial neuropsychological performance and rate of change on the MMSE and CDR Sum of Boxes.

RESULTS

Preservation of working memory, but not episodic memory, in the mild cognitive impairment and early dementia stages of AD relates to slower rate of functional decline.

DISCUSSION

These findings are relevant for estimating the rate of decline in AD clinical trials and in counseling patients and families. Improving working memory performance as a possible avenue to decrease the rate of functional decline in AD dementia warrants closer investigation.

Emergence of mild cognitive impairment in late middle-aged adults in the wisconsin registry for Alzheimer's prevention

AIM

It is difficult to reliably detect the earliest signs of Alzheimer's disease (AD)-associated cognitive impairment. Our aim was to compare 3 psychometric methods of identifying amnestic mild cognitive impairment (aMCI) in a middle-aged longitudinal cohort enriched for AD risk.

METHODS

Wisconsin Registry for Alzheimer's Prevention (WRAP) participants with 3 waves of cognitive assessment over approximately 6 years were coded as meeting each of 3 psychometric aMCI definitions: (a) 'aMCI standard-baseline' used published norms to establish cutoffs for baseline performance; (b) 'aMCI robust-baseline' applied WRAP-specific robust norms to baseline, and (c) 'aMCI robust-multiwave' applied these robust norms across 3 waves of assessment. Each group was compared to a cognitively healthy subset.

RESULTS

Half the aMCI standard-baseline and one third of the aMCI robust-baseline group reverted to normal ranges at follow-up. Only the aMCI robust-multiwave method had an aMCI × age interaction showing significantly worse age-related memory declines in the aMCI group compared to the cognitively healthy group over 6 years of follow-up.

CONCLUSION

Both cross-sectional methods showed instability over time, with many reverting to normal performance after baseline. The multiwave approach identified a group who showed progressive memory declines over 3 visits. Being able to detect progressive decline in late middle age is a critical step in improving prevention efforts.

Intraindividual variability in domain-specific cognition and risk of mild cognitive impairment and dementia

Intraindividual variability among cognitive domains may predict dementia independently of interindividual differences in cognition. A multidomain cognitive battery was administered to 2305 older adult women (mean age 74 years) enrolled in an ancillary study of the Women's Health Initiative. Women were evaluated annually for probable dementia and mild cognitive impairment (MCI) for an average of 5.3 years using a standardized protocol. Proportional hazards regression showed that lower baseline domain-specific cognitive scores significantly predicted MCI (N = 74), probable dementia (N = 45), and MCI or probable dementia combined (N = 101) and that verbal and figural memory predicted each outcome independently of all other cognitive domains. The baseline intraindividual standard deviation across test scores (IAV Cognitive Domains) significantly predicted probable dementia and this effect was attenuated by interindividual differences in verbal episodic memory. Slope increases in IAV Cognitive Domains across measurement occasions (IAV Time) explained additional risk for MCI and MCI or probable dementia, beyond that accounted for by interindividual differences in multiple cognitive measures, but risk for probable dementia was attenuated by mean decreases in verbal episodic memory slope. These findings demonstrate that within-person variability across cognitive domains both at baseline and longitudinally independently accounts for risk of cognitive impairment and dementia in support of the predictive utility of within-person variability.

Cardiovascular risks and brain function: a functional magnetic resonance imaging study of executive function in older adults

Cardiovascular (CV) risk factors, such as hypertension, diabetes, and hyperlipidemia are associated with cognitive impairment and risk of dementia in older adults. However, the mechanisms linking them are not clear. This study aims to investigate the association between aggregate CV risk, assessed by the Framingham general cardiovascular risk profile, and functional brain activation in a group of community-dwelling older adults. Sixty participants (mean age: 64.6 years) from the Brain Health Study, a nested study of the Baltimore Experience Corps Trial, underwent functional magnetic resonance imaging using the Flanker task. We found that participants with higher CV risk had greater task-related activation in the left inferior parietal region, and this increased activation was associated with poorer task performance. Our results provide insights into the neural systems underlying the relationship between CV risk and executive function. Increased activation of the inferior parietal region may offer a pathway through which CV risk increases risk for cognitive impairment.

Preventing cognitive decline in preclinical Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease leading to cognitive decline, dementia, and ultimately death. Despite extensive R&D efforts, there are no diseases modifying treatments for AD available. The stage in which patients receive a clinical diagnosis of probable AD may be too late for disease modifying pharmacotherapy. Prevention strategies may be required to successfully tackle AD. Preclinical AD applies to over half of all healthy elderly subjects and manifests by signs of amyloid deposition and/or neuronal injury in the brain, preceding the stage in which symptoms of dementia, cognitive and functional impairment become observable. Prevention trials in preclinical AD require longer and larger clinical trials using biomarkers and cognitive endpoints, which requires collaboration across academia, government and industry.

White matter tract integrity metrics reflect the vulnerability of late-myelinating tracts in Alzheimer's disease

Post-mortem and imaging studies have observed that white matter (WM) degenerates in a pattern inverse to myelin development, suggesting preferential regional vulnerabilities influencing cognitive decline in AD. This study applied novel WM tract integrity (WMTI) metrics derived from diffusional kurtosis imaging (DKI) to examine WM tissue properties in AD within this framework. Using data from amnestic mild cognitive impairment (aMCI, n = 12), AD (n = 14), and normal control (NC; n = 15) subjects, mixed models revealed interaction effects: specific WMTI metrics of axonal density and myelin integrity (i.e. axonal water fraction, radial extra-axonal diffusivity) in late-myelinating tracts (i.e. superior and inferior longitudinal fasciculi) changed in the course of disease, but were stable in the initial stages for early-myelinating tracts (i.e. posterior limb of the internal capsule, cerebral peduncles). WMTI metrics in late-myelinating tracts correlated with semantic verbal fluency, a cognitive function known to decline in AD. These findings corroborate the preferential vulnerability of late-myelinating tracts, and illustrate an application of WMTI metrics to characterizing the regional course of WM changes in AD.

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We investigated the vulnerability of late-myelinating tracts in AD using WMTI metrics.

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WMTI metrics are derived from the biophysical modeling of the DKI signal.

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These metrics indicate pathological features like axonal density and myelin integrity.

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WMTI metrics were largely stable in early-myelinating tracts through the course of AD.

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Axonal density loss & myelin breakdown were observed in late-myelinating tracts.

Cerebrospinal fluid aβ to tau ratio and postoperative cognitive change

OBJECTIVE

Determination of biomarker and neuropathogenesis of postoperative cognitive change (POCC) or postoperative cognitive dysfunction.

BACKGROUND

POCC is one of the most common postoperative complications in elderly patients. Whether preoperative cerebrospinal fluid (CSF) β-amyloid protein (Aβ) to tau ratio, an Alzheimer disease biomarker, is a biomarker for risk of POCC remains unknown. We therefore set out to assess the association between preoperative CSF Aβ42 or Aβ40 to tau ratio and POCC.

METHODS

Patients who had total hip/knee replacement were enrolled. The CSF was obtained during the administration of spinal anesthesia. Cognitive tests were performed with these participants at 1 week before and at 1 week and 3 to 6 months after the surgery. Z scores of the changes from preoperative to postoperative on several key domains of the cognitive battery were determined. We then examined the association between preoperative CSF Aβ42/tau or Aβ40/tau ratio and the outcome measures described earlier, adjusting for age and sex.

RESULTS

Among the 136 participants (mean age = 71 ± 5 years; 55% men), preoperative CSF Aβ42/tau ratio was associated with postoperative Hopkins Verbal Learning Test Retention [Z score = 8.351; age, sex-adjusted (adj.) P = 0.003], and the Benton Judgment of Line Orientation (Z score = 1.242; adj. P = 0.007). Aβ40/tau ratio was associated with Brief Visuospatial Memory Test Total Recall (Z score = 1.045; adj. P = 0.044).

CONCLUSIONS

Preoperative CSF Aβ/tau ratio is associated with postoperative changes in specific cognitive domains. The presence of the Alzheimer's disease biomarker, specifically the Aβ/tau ratio, may identify patients at higher risk for cognitive changes after surgery.

Prediction of outcomes in MCI with (123)I-IMP-CBF SPECT: a multicenter prospective cohort study

Objective

The multicenter prospective cohort study (Japan Cooperative SPECT Study on Assessment of Mild Impairment of Cognitive Function: J-COSMIC) aimed to examine the value of ¹²³I-N-isopropyl-4-iodoamphetamine cerebral blood flow (IMP-CBF) SPECT in regards to early diagnosis of Alzheimer’s disease (AD) in patients with mild cognitive impairment (MCI).

Methods

Three hundred and nineteen patients with amnestic MCI at 41 participating institutions each underwent clinical and neuropsychological examinations and ¹²³I-IMP-CBF SPECT at baseline. Subjects were followed up periodically for 3 years, and progression to dementia was evaluated. SPECT images were classified as AD/DLB (dementia with Lewy bodies) pattern and non-AD/DLB pattern by central image interpretation and automated region of interest (ROI) analysis, respectively. Logistic regression analyses were used to assess whether baseline ¹²³I-IMP-CBF SPECT was predictive of longitudinal clinical outcome.

Results

Ninety-nine of 216 amnestic MCI patients (excluding 3 cases with epilepsy (n = 2) or hydrocephalus (n = 1) and 100 cases with incomplete follow-up) converted to AD within the observation period. Central image interpretation and automated ROI analysis predicted conversion to AD with 56 and 58 % overall diagnostic accuracy (sensitivity, 76 and 81 %; specificity, 39 and 37 %), respectively. Multivariate logistic regression analysis identified SPECT as a predictor, which distinguished AD converters from non-converters. The odds ratio for a positive SPECT to predict conversion to AD with automated ROI analysis was 2.5 and combining SPECT data with gender and mini-mental state examination (MMSE) further improved classification (joint odds ratio 20.08).

Conclusions

¹²³I-IMP-CBF SPECT with both automated ROI analysis and central image interpretation was sensitive but relatively nonspecific for prediction of clinical outcome during the 3-year follow-up in individual amnestic MCI patients. A combination of statistically significant predictors, both SPECT with automated ROI analysis and neuropsychological evaluation, may increase predictive utility.

Electronic supplementary material

The online version of this article (doi:10.1007/s12149-013-0768-7) contains supplementary material, which is available to authorized users.

Decreased white matter integrity in neuropsychologically defined mild cognitive impairment is independent of cortical thinning

Improved understanding of the pattern of white matter changes in early and prodromal Alzheimer’s disease (AD) states such as mild cognitive impairment (MCI) is necessary to support earlier preclinical detection of AD, and debate remains whether white matter changes in MCI are secondary to gray matter changes. We applied neuropsychologically based MCI criteria to a sample of normally aging older adults; 32 participants met criteria for MCI and 81 participants were classified as normal control (NC) subjects. Whole-head high resolution T1 and diffusion tensor imaging scans were completed. Tract-Based Spatial Statistics was applied and a priori selected regions of interest were extracted. Hippocampal volume and cortical thickness averaged across regions with known vulnerability to AD were derived. Controlling for corticalthic kness, the MCI group showed decreased average fractional anisotropy (FA) and decreased FA in parietal white matter and in white matter underlying the entorhinal and posterior cingulate cortices relative to the NC group. Statistically controlling for cortical thickness, medial temporal FA was related to memory and parietal FA was related to executive functioning. These results provide further support for the potential role of white matter integrity as an early biomarker for individuals at risk for AD and highlight that changes in white matter may be independent of gray matter changes.

Relationship between Stroop performance and resting state functional connectivity in cognitively normal older adults

OBJECTIVE

Early biomarkers of Alzheimer's disease (AD) are needed for developing therapeutic interventions. Measures of attentional control in Stroop-type tasks discriminate healthy aging from early stage AD and predict future development of AD in cognitively normal individuals. Disruption in resting state functional connectivity MRI (rs-fcMRI) has been reported in AD and in healthy controls at risk for AD. We explored the relationship among Stroop performance, rs-fcMRI, and CSF Aβ₄₂ levels in cognitively normal older adults.

METHOD

A computerized Stroop task (along with standard neuropsychological measures), rs-fcMRI, and CSF were obtained in 237 cognitively normal older adults. We compared the relationship between Stroop performance, including measures from reaction distributional analyses, and composite scores from four resting state networks (RSNs; default mode [DMN], salience [SAL], dorsal attention [DAN], and sensory-motor [SMN]), and the modulatory influence of CSF Aβ₄₂ levels.

RESULTS

A larger Stroop effect in errors was associated with reduced rs-fcMRI within the DMN and SAL. Reaction time (RT) distributional analyses indicated the slow tail of the RT distribution was related to reduced rs-fcMRI functional connectivity within the SAL. Standard psychometric measures were not related to RSN composite scores. A relationship between Stroop performance and DMN (but not SAL) functional connectivity was stronger in CSF Aβ₄₂-positive individuals.

CONCLUSIONS

A link exists between RSN composite scores and specific attentional performance measures. Both measures may be sensitive biomarkers for AD.

Event-related potential index of age-related differences in memory processes in adults with Down syndrome

A major goal of aging research is to identify early markers of age-related cognitive decline. Persons with Down syndrome (DS) experience accelerated aging and high risks for dementia, making them a valuable albeit understudied model for testing such markers. This study examined event-related potential (ERP) indices of visual memory in younger (19-25 years) and older (35-40 years) adults with DS using a passive viewing paradigm that did not require memorization or behavioral responses. ERPs were recorded in response to unfamiliar urban and nature scenes, with some images presented once and others repeated multiple times. Within 600 to 900 milliseconds after stimulus onset, repeated stimuli elicited more positive amplitudes in younger participants, indicating stimilus recognition. ERPs of older adults did not show such increases, suggesting reduced memory functioning. ERP indices were unrelated to participants' intellectual functioning, but did correlate with age and caregiver-reported lethargy/withdrawal behaviors. Passive ERP measures of memory processes are sensitive to early stages of cognitive decline in DS and are promising markers of cognitive risk for future aging studies.

Finger agnosia and cognitive deficits in patients with Alzheimer's disease

The purpose of this study was to examine the presence of finger agnosia in patients with Alzheimer's disease (AD) and to determine if level of finger agnosia was related to cognitive impairment. Finger agnosia is a sensitive measure of cerebral impairment and is associated with neurofunctional areas implicated in AD. Using a standardized and norm-referenced approach, results indicated that patients with AD evidenced significantly decreased performance on tests of bilateral finger agnosia compared with healthy age-matched controls. Finger agnosia was predictive of cognitive dysfunction on four of seven domains, including: Crystallized Language, Fluid Processing, Associative Learning, and Processing Speed. Results suggest that measures of finger agnosia, a short and simple test, may be useful in the early detection of AD.

Longitudinal change in neuropsychological performance using latent growth models: a study of mild cognitive impairment

The goal of the current study was to examine cognitive change in both healthy controls (n = 229) and individuals with mild cognitive impairment (MCI) (n = 397) from the Alzheimer's Disease Neuroimaging Initiative (ADNI). We applied latent growth modeling to examine baseline and longitudinal change over 36 months in five cognitive factors derived from the ADNI neuropsychological test battery (memory, executive function/processing speed, language, attention and visuospatial). At baseline, MCI patients demonstrated lower performance on all of the five cognitive factors when compared to controls. Both controls and MCI patients declined on memory over 36 months; however, the MCI patients declined at a significantly faster rate than controls. The MCI patients also declined over 36 months on the remaining four cognitive factors. In contrast, the controls did not exhibit significant change over 36 months on the non-memory cognitive factors. Within the MCI group, executive function declined faster than memory, while the other factor scores changed slower than memory over time. These findings suggest different patterns of cognitive change in healthy older adults and MCI patients. The findings also suggest that, when compared with memory, executive function declines faster than other cognitive factors in patients with MCI. Thus, decline in non-memory domains may be an important feature for distinguishing healthy older adults and persons with MCI.

Decreased cognitive function in extended family members from the single late-onset-Alzheimer's-disease pedigree

A family history of dementia is associated with an increased risk of developing Alzheimer's disease (AD) late in life (LOAD). This study marked the first attempt to assess the familial contribution to differences in cognitive performance in a large family-based group in the Chinese community. We enrolled 168 participants without dementia from a single pedigree with 9 probable AD patients diagnosed after age 65. These participants were evaluated with a comprehensive neuropsychological battery, the Chinese version of the Mini Mental State Examination, and the Alzheimer Disease Assessment Scale-Cognitive Subscale. Analyses found that extended family members of the LOAD pedigree showed similar performance on measures of global cognitive function and semantic memory compared to controls, but lower scores on episodic memory, attention, and executive function measures. These results indicate that the genetic influences on certain sub-cognitive domains are more detectable despite normal global cognitive function, and that family members with the LOAD pedigree are at risk for developing LOAD by virtue of their family history with an additive risk due to increased age. The findings in this study support the importance of documenting if there is a positive family history of AD in clinical evaluations.

Blood pressure and cognition among older adults: a meta-analysis

Hypertension has adverse effects on cognition, can alter cerebral vasculature integrity, and is associated with the pathogenesis of dementia. Using meta-analysis, we correlated blood pressure to multiple cognitive domains among older adults free of clinical stroke and dementia. We identified 230 studies indexed in PubMed and PsycINFO relating blood pressure and cognition. After applying exclusion criteria, we selected n = 12 articles with n = 4,076 participants (age range 43-91 years). Meta-analysis yielded an association between blood pressure and episodic memory (r = -.18, p < .001) and between blood pressure and global cognition (r = -.07, p < .001). When limiting analyses to studies adjusting for vascular covariates (n = 8, n = 2,141), blood pressure was modestly related to global cognition (r = -.11, p < .001), attention (r = .14, p = .002), and episodic memory (r = -.20, p < .001) with a trend for language (r = -.22, p = .07). Findings underscore the need to manage blood pressure as a key prevention method in minimizing abnormal cognitive aging prior to the onset of clinical dementia.

Which neuropsychological tests predict progression to Alzheimer's disease in Hispanics?

OBJECTIVE

To investigate which neuropsychological tests predict eventual progression to Alzheimer's disease (AD) in both Hispanic and non-Hispanic individuals. Although our approach was exploratory, we predicted that tests that underestimate cognitive ability in healthy aging Hispanics might not be sensitive to future cognitive decline in this cultural group.

METHOD

We compared first-year data of 22 older adults (11 Hispanic) who were diagnosed as cognitively normal but eventually developed AD (decliners), to 60 age- and education-matched controls (27 Hispanic) who remained cognitively normal. To identify tests that may be culturally biased in our sample, we compared Hispanic with non-Hispanic controls on all tests and asked which tests were sensitive to future decline in each cultural group.

RESULTS

Compared to age-, education-, and gender-matched non-Hispanic controls, Hispanic controls obtained lower scores on tests of language, executive function, and some measures of global cognition. Consistent with our predictions, some tests identified non-Hispanic, but not Hispanic, decliners (vocabulary, semantic fluency). Contrary to our predictions, a number of tests on which Hispanics obtained lower scores than non-Hispanics nevertheless predicted eventual progression to AD in both cultural groups (e.g., Boston Naming Test [BNT], Trails A and B).

CONCLUSIONS

Cross-cultural variation in test sensitivity to decline may reflect greater resistance of medium difficulty items to decline and bilingual advantages that initially protect Hispanics against some aspects of cognitive decline commonly observed in non-Hispanics with preclinical AD. These findings highlight a need for further consideration of cross-cultural differences in neuropsychological test performance and development of culturally unbiased measures.

Limitations for interpreting failure on individual subtests of the Montreal Cognitive Assessment

BACKGROUND

The Montreal Cognitive Assessment (MoCA) is sensitive to mild forms of cognitive impairment in geriatric populations and asks questions under the subheadings visuospatial/executive, naming, attention, language, abstraction, delayed recall, and orientation. This study examined the extent to which these subsets of MoCA items evaluate their intended cognitive domains.

METHODS

Clinical data from 185 geriatric memory clinic outpatients who underwent cognitive screening and subsequent neuropsychological assessment were analyzed. Factor analysis of their neuropsychological test scores identified 5 cognitive domains memory, language, visuospatial ability, attention/processing speed, and cognitive control. Scores on MoCA subtests were examined for their correlations with individual factor scores and for their sensitivity and specificity in predicting impairment within each domain.

RESULTS

The MoCA subtest scores correlated significantly but modestly with neuropsychological test factor scores in their corresponding domains, for example, the correlation between 5-word recall and the memory factor was 0.46. However, subtest scores were poor predictors of impaired performance on the tests contributing to each cognitive domain. The best predictive accuracy was seen for the visuospatial/executive subtest that showed fair accuracy at predicting impairment on tests in the visuospatial domain. Other subtests showed unacceptably poor levels of accuracy when predicting impaired scores in their respective domains (60%-67%).

CONCLUSIONS

In a sample of geriatric outpatients referred for cognitive assessment, performance on individual items and subtests of the MoCA yields insufficient information to draw conclusions about impairment in specific cognitive domains as determined by neuropsychological testing.

Decreased recall of primacy words predicts cognitive decline

One of the cognitive changes associated with Alzheimer's disease is a diminution of the primacy effect, i.e., the tendency toward better recall of items studied early on a list compared with the rest. We examined whether learning and recall of primacy words predicted subsequent cognitive decline in 204 elderly subjects who were non-demented and cognitively intact when first examined. Our results show that poorer primacy performance in the Rey Auditory Verbal Learning Test delayed recall trials, but not in immediate recall trials, is an effective predictor of subsequent decline in general cognitive function. This pattern of performance can be interpreted as evidence that failure to consolidate primacy items is a marker of cognitive decline.

The SIST-M: predictive validity of a brief structured clinical dementia rating interview

BACKGROUND

We have previously established the reliability and cross-sectional validity of the SIST-M (Structured Interview and Scoring Tool-Massachusetts Alzheimer's Disease Research Center), a shortened version of an instrument shown to predict progression to Alzheimer disease (AD), even among persons with very mild cognitive impairment (vMCI).

OBJECTIVE

To test the predictive validity of the SIST-M.

METHODS

Participants were 342 community-dwelling, nondemented older adults in a longitudinal study. Baseline Clinical Dementia Rating (CDR) ratings were determined by either (1) clinician interviews or (2) a previously developed computer algorithm based on 60 questions (of a possible 131) extracted from clinician interviews. We developed age+sex+education-adjusted Cox proportional hazards models using CDR-sum-of-boxes (CDR-SB) as the predictor, where CDR-SB was determined by either a clinician interview or an algorithm; models were run for the full sample (n = 342) and among those jointly classified as vMCI using clinician-based and algorithm-based CDR ratings (n = 156). We directly compared predictive accuracy using time-dependent receiver operating characteristic (ROC) curves.

RESULTS

AD hazard ratios (HRs) were similar for clinician-based and algorithm-based CDR-SB: for a 1-point increment in CDR-SB, the respective HRs [95% confidence interval (CI)] were 3.1 (2.5, 3.9) and 2.8 (2.2, 3.5); among those with vMCI, the respective HRs (95% CI) were 2.2 (1.6, 3.2) and 2.1 (1.5, 3.0). Similarly high predictive accuracy was achieved: the concordance probability (weighted average of the area-under-the-ROC curves) over follow-up was 0.78 versus 0.76 using clinician-based versus algorithm-based CDR-SB.

CONCLUSION

CDR scores based on items from this shortened interview had high predictive ability for AD-comparable to that using a lengthy clinical interview.

Susceptibility to distraction during reading in young, young-old, and old-old adults

BACKGROUND/STUDY CONTEXT: Susceptibility to distraction during reading may increase with age, resulting in comprehension errors. Neurological integrity and cognitive reserve are possible covariates of age-related distraction susceptibility. The current study investigated distraction susceptibility in three age groups (young, young-old, and old-old), and examined the covariation patterns of variable sets associated with neurological integrity and cognitive reserve.

METHODS

Participants responded to comprehension questions after reading stories that included semantically related or semantically unrelated distractors. Neurological integrity measures consisted of Mini-Mental State Examination, Selective Reminding, and Category Fluency. Cognitive reserve measures consisted of education and vocabulary.

RESULTS

Old-old adults were more likely than young and young-old adults to select distractors when responding to comprehension questions (24.02%, 11.95%, 3.68%, respectively). Age-related distraction variance significantly overlapped neurological variance, and became more transparent after cognitive reserve variance was controlled.

CONCLUSION

This study augments previous age-related distraction research by highlighting (a) the increase in distraction susceptibility in adults over 79, particularly when distractors are semantically related; (b) the influence of age-related neurological integrity on distraction; and (c) the possibility that education and verbal experience may decrease distraction susceptibility, consistent with cognitive reserve frameworks.