Developing a Brief Neuropsychological Battery for Early Diagnosis of Cognitive Impairment

Cognitive reserve is associated with education, social determinants, and cognitive outcomes among older American Indians in the Strong Heart Study

Cognitive reserve, a component of resilience, may be conceptualized as the ability to overcome accumulating neuropathology and maintain healthy aging and function. However, research measuring and evaluating it in American Indians is needed. We recruited American Indians from 3 regional centers for longitudinal examinations (2010-13, n = 818; 2017-19, n = 403) including MRI, cognitive, clinical, and questionnaire data. We defined cognitive reserve by measuring the residual from individual regressions of cognitive tests over imaged brain volumes, adjusted for age and sex. Analyses examined three different metrics of cognitive reserve against sociodemographic, clinical, and longitudinal cognitive data in causal mediation models. Better cognitive reserve was significantly associated with more education, higher income, lower prevalence of depression, lower prevalence of diabetes, and lower prevalence of kidney disease, but we found no statistically significant evidence for an association with plasma biomarkers for Alzheimer's disease and related dementias, APOE e4 carrier status, alcohol use, body mass, or hypertension. Better cognitive reserve was associated with better cognitive function over mean 6.7 years follow-up (range 4-9 years); and the association for education with cognition over time was mediated in part (15-24%) by cognitive reserve. Cognitive reserve, although challenging to measure, appears important for understanding the range of cognitive aging in American Indians.

Plasma biomarkers of Alzheimer's disease and related dementias in American Indians: The Strong Heart Study

INTRODUCTION

Identification of Alzheimer's disease (AD) needs inexpensive, noninvasive biomarkers, with validation in all populations.

METHODS

We collected plasma markers in older American Indian individuals: phosphorylated-tau181 (pTau181); amyloid-beta (Aβ) 40,42; glial fibrillary acidic protein (GFAP); and neurofilament light chain (NfL). Plasma markers were analyzed for discriminant properties with cognitive status and etiology using receiver operating characteristic (ROC) analysis.

RESULTS

PTau181, GFAP, NfL plasma values were significantly associated with cognition, but Aβ were not. Discriminant performance was moderate for individual markers, with pTau181, GFAP, NfL performing best, but an empirically selected panel of markers (age, sex, education, pTau181, GFAP, NfL, Aβ4240 ratio) had excellent discriminant performance (AUC > 0.8).

DISCUSSION

In American Indian individuals, pTau181 and Aβ values suggested more common pathology than in majority populations. Aβ was less informative than in other populations; however, all four markers were needed for a best-performing dementia diagnostic model. These data validate utility of AD plasma markers, while suggesting population-specific diagnostic characteristics.

Subjective cognitive decline, APOE e4 allele, and the risk of neurocognitive disorders: Age- and sex-stratified cohort study

OBJECTIVE

Subjective cognitive decline and APOE e4 allele (APOE4) are known predictors of mild cognitive impairment and dementia (mild cognitive impairment/dementia), with recent evidence showing interaction between subjective cognitive decline and APOE4 in amplifying the risk of mild cognitive impairment/dementia. However, the literature is unclear whether the interaction effect is seen across various age and sex strata. This study examined the interaction between subjective cognitive decline and APOE4-across different age and sex strata-on the risk of mild cognitive impairment/dementia.

METHODS

This cohort study included 16,221 participants aged ⩾50 years and had normal cognition at baseline. Participants were evaluated for subjective cognitive decline and APOE4 at baseline, and followed-up almost annually for mild cognitive impairment/dementia (median follow-up = 4.5 years). Interaction effects were examined in Cox regression using Relative Excess Risk due to Interaction, stratified by age (⩽70 vs >70 years) and sex.

RESULTS

Subjective cognitive decline and APOE4 were independently associated with mild cognitive impairment/dementia (hazard ratio: 1.4-1.8), with the highest risk when subjective cognitive decline and APOE4 co-occurred (hazard ratio: 2.6). APOE4 amplified the association between subjective cognitive decline and mild cognitive impairment/dementia in older women (Relative Excess Risk due to Interaction 1.0; 95% confidence interval = [0.3, 1.6]), but not in other age or sex strata. Among older women, half of them developed mild cognitive impairment/dementia by 12.1 years in the absence of subjective cognitive decline or APOE4. This duration shortened to 8.1-10.3 years in the presence of either subjective cognitive decline or APOE4, and to 4.4 years in the presence of both subjective cognitive decline and APOE4. Interaction effect among older women remained consistent when alternate outcomes were used (i.e. mild cognitive impairment and dementia due to Alzheimer's disease; dementia; and Alzheimer's dementia) (Relative Excess Risk due to Interaction 1.2-2.5).

CONCLUSIONS

APOE4 amplifies the association between subjective cognitive decline and neurocognitive disorders in older women, with the findings suggesting the need for further research to delineate underlying neurobiology. APOE4 may potentially have a role in facilitating further risk stratification of older women with subjective cognitive decline in clinical practice.

Neuropsychological Profile of Early Cognitive Impairment in Cerebral Small Vessel Disease

INTRODUCTION

The neuropsychological feature of vascular mild cognitive impairment is a deficit of the frontal-subcortical circuit; however, the features in the early stage are not consistent. In the present study, we aimed to investigate the neuropsychological features of the very early stage of cognitive impairment with cerebral small vessel disease (CSVD) and to elucidate the cognitive differences among CSVD subtypes.

METHODS

A comprehensive neuropsychological test battery was applied to nondemented subjects scoring below the cutoff point 26 of the Japanese version of the Montreal Cognitive Assessment. After factor analysis was conducted to identify covert cognitive factors in the battery, correlation analyses were performed between the factors and CSVD subtypes: white matter hyperintensity (WMH), lacunar infarcts (LIs), cerebral microbleeds (CMBs), perivascular spaces, and cortical atrophy.

RESULTS

Among the 465 recruited patients, 139 underwent a full neuropsychological test battery. Through factor analysis, the following three factors were extracted: executive function, memory, and attention. Of the CSVD features, total WMH was correlated with executive function and memory, whereas deep WMH was correlated with memory alone. Of the CSVD subtypes, LIs and CMBs were correlated only with executive function. Frontal and posterior atrophy were correlated with memory and attention, whereas medial temporal atrophy was correlated with memory alone.

CONCLUSIONS

Executive dysfunction accompanied by subtle impairment of memory and processing speed was the main feature of neuropsychological profiles in the subjects with CSVD, even in the very early stage. Furthermore, each CSVD feature and focal cerebral atrophy are associated with cognitive impairment.

Tau deposition and structural connectivity demonstrate differential association patterns with neurocognitive tests

Tau neurofibrillary tangles have a central role in the pathogenesis of Alzheimer’s Disease (AD). Mounting evidence indicates that the propagation of tau is assisted by brain connectivity with weakened white-matter integrity along the propagation pathways. Recent advances in tau positron emission tomography tracers and diffusion magnetic resonance imaging allow the visualization of tau pathology and white-matter connectivity of the brain in vivo. The current study aims to investigate how tau deposition and structural connectivity are associated with memory function in prodromal AD. In this study, tau accumulation and structural connectivity data from 83 individuals (57 cognitively normal participants and 26 participants with mild cognitive impairment) were associated with neurocognitive test scores. Statistical analyses were performed in 70 cortical/subcortical brain regions to determine: 1. the level of association between tau and network metrics extracted from structural connectivity and 2. the association patterns of brain memory function with tau accumulation and network metrics. The results showed that tau accumulation and network metrics were correlated in early tau deposition regions. Furthermore, tau accumulation was associated with worse performance in almost all neurocognitive tests performance evaluated in the study. In comparison, decreased network connectivity was associated with declines in the delayed memory recall in Craft Stories and Benson Figure Copy. Interaction analysis indicates that tau deposition and dysconnectivity have a synergistic effect on the delayed Benson Figure Recall. Overall, our findings indicate that both tau deposition and structural dysconnectivity are associated with neurocognitive dysfunction. They also suggest that tau-PET may have better sensitivity to neurocognitive performance than diffusion MRI-derived measures of white-matter connectivity.

Neuropsychiatric symptoms in early stage of Alzheimer's and non-Alzheimer's dementia, and the risk of progression to severe dementia

BACKGROUND

Neuropsychiatric symptoms (NPSs) in early dementia have been suggested to predict a higher risk of dementia progression. However, the literature is not yet clear whether the risk is similar across Alzheimer's dementia (AD) and non-Alzheimer's dementia (non-AD), as well as across different NPSs. This study examined the association between NPSs in early dementia and the risk of progression to severe dementia, specifically in AD and non-AD, as well as across various NPSs.

METHOD

This cohort study included 7,594 participants who were ≥65 years and had early dementia (global Clinical Dementia Rating [CDR] = 1). Participants completed Neuropsychiatric-Inventory-Questionnaire at baseline and were followed-up almost annually for progression to severe dementia (global CDR = 3) (median follow-up = 3.5 years; interquartile range = 2.1-5.9 years). Cox regression was used to examine progression risk, stratified by AD and non-AD.

RESULTS

The presence of NPSs was associated with risk of progression to severe dementia, but primarily in AD (HR 1.4, 95% confidence interval [CI]: 1.1-1.6) and not in non-AD (HR 0.9, 95% CI: 0.5-1.5). When comparing across various NPSs, seven NPSs in AD were associated with disease progression, and they were depression, anxiety, apathy, delusions, hallucinations, irritability and motor disturbance (HR 1.2-1.6). In contrast, only hallucinations and delusions were associated with disease progression in non-AD (HR 1.7-1.9).

CONCLUSIONS

NPSs in early dementia-especially among individuals with AD-can be useful prognostic markers of disease progression. They may inform discussion on advanced care planning and prompt clinical review to incorporate evidence-based interventions that may address disease progression.

Assessment of dementia in a clinical sample of persons with intellectual disability

BACKGROUND

Assessment of age-associated disorders has become increasingly important.

METHODS

In a clinical setting, people with intellectual disability with and without dementia were assessed retrospectively using the Neuropsychological Test Battery (NTB) and the Dementia Questionnaire for People with Learning Disabilities (DLD) at two different times to analyse neuropsychological changes and diagnostic validity. One group (n = 44) was assessed with both instruments, while the DLD was applied in 71 patients.

RESULTS

In the NTB (n = 44), only patients with dementia (n = 26) showed a decline in the NTB total score and three subscales. Receiver operating characteristic analysis revealed a diagnostic sensitivity of .67, a specificity of .81, and an area under the curve (AUC) of .767. In the DLD group (n = 71), only those with dementia displayed a decrease in the cognitive and social scale; diagnostic sensitivity and specificity values were low (.61/.63) and the AUC was .704.

CONCLUSIONS

Neuropsychological assessment was sensitive to detect cognitive changes over time. Sensitivity values of both instruments suggest a reassessment at a later time point.

Trajectories of subjective cognitive decline, and the risk of mild cognitive impairment and dementia

BACKGROUND

In cognitively normal individuals, subjective cognitive decline (SCD) has been reported to predict MCI and dementia (MCI/dementia). However, prior studies mostly captured SCD at single time-points without considering the longitudinal course of SCD. This study examined whether the trajectories of SCD provide any added information-beyond one-time assessments of SCD-on the risk of MCI/dementia.

METHODS

This cohort study included 5661 participants from the Alzheimer's Disease Centers across the USA, who were ≥ 50 years and had normal cognition in the first-four annual visits (year 1 to year 4). The participants were evaluated for SCD in the first-four annual visits (year 1 to year 4), and followed-up almost annually (year 4 up to year 14) for incident MCI/dementia. SCD trajectories (as identified from latent-class-growth-curve-analysis) were included in Cox regression to estimate their risks of MCI/dementia, with analyses further stratified by age (< 75 years versus ≥ 75 years; based on median-split).

RESULTS

Compared to those without SCD (in the first-four annual visits), Intermittent SCD (i.e., reported in 1-2 of the first-four annual visits) predicted a higher risk (HR 1.4) and Persistent SCD (i.e., reported in 3-4 of the first-four annual visits) predicted the highest risk (HR 2.2), with the results remaining significant even after adjusting for baseline SCD. Age-stratified analysis revealed that the risk associated with Intermittent SCD was only present in older individuals, while risk related to Persistent SCD was consistently present across the younger and older age groups. Age compounded the effects of the trajectories, whereby older individuals with Persistent SCD had > 75% probability of developing MCI/dementia by 10 years, in contrast to < 25% probability by 10 years in younger individuals with No SCD.

CONCLUSIONS

The findings demonstrate the utility of SCD trajectories-especially when used in combination with age strata-in identifying high-risk populations for preventive interventions and trials. They also suggest a potential modification in the current SCD criteria, with the inclusion of "persistent SCD over several years" as a feature of SCD plus.

Development and Preliminary Validation of Standardized Regression-Based Change Scores as Measures of Transitional Cognitive Decline

OBJECTIVE

An increasing focus in Alzheimer's disease and aging research is to identify transitional cognitive decline. One means of indexing change over time in serial cognitive evaluations is to calculate standardized regression-based (SRB) change indices. This paper includes the development and preliminary validation of SRB indices for the Uniform Data Set 3.0 Neuropsychological Battery, as well as base rate data to aid in their interpretation.

METHOD

The sample included 1,341 cognitively intact older adults with serial assessments over 0.5-2 years in the National Alzheimer's Coordinating Center Database. SRB change scores were calculated in half of the sample and then validated in the other half of the sample. Base rates of SRB decline were evaluated at z-score cut-points, corresponding to two-tailed p-values of .20 (z = -1.282), .10 (z = -1.645), and .05 (z = -1.96). We examined convergent associations of SRB indices for each cognitive measure with each other as well as concurrent associations of SRB indices with clinical dementia rating sum of box scores (CDR-SB).

RESULTS

SRB equations were able to significantly predict the selected cognitive variables. The base rate of at least one significant SRB decline across the entire battery ranged from 26.70% to 58.10%. SRB indices for cognitive measures demonstrated theoretically expected significant positive associations with each other. Additionally, CDR-SB impairment was associated with an increasing number of significantly declined test scores.

CONCLUSIONS

This paper provides preliminary validation of SRB indices in a large sample, and we present a user-friendly tool for calculating SRB values.

Active case finding of dementia in ambulatory care settings: a comparison of three strategies

BACKGROUND AND PURPOSE

To reduce the diagnostic gap of dementia, three strategies can be employed for case finding of cognitive impairment in ambulatory care settings, namely using informant report, brief cognitive test or a combination of informant report and brief cognitive test. The right strategy to adopt across different healthcare settings remains unclear. This diagnostic study compared the performance of the three strategies for detecting dementia (primary aim), as well as for detecting both mild cognitive impairment (MCI) and dementia (secondary aim).

METHODS

Participants aged ≥65 years (n = 11 057) were recruited from Alzheimer's Disease Centers across the USA. Participants provided data on an informant report (Functional Activities Questionnaire), brief cognitive test (four-item short variant of Montreal Cognitive Assessment) and a combined measure with informant report and brief cognitive test (sum of Functional Activities Questionnaire and Montreal Cognitive Assessment short variant). They also received standardized assessments (clinical history, physical examination and neuropsychological testing) to diagnose MCI and dementia. Areas under the receiver operating characteristic curve (AUCs) of the three strategies were compared using the DeLong method, with AUC > 90% indicating excellent performance.

RESULTS

All three strategies had excellent performance in detecting dementia, although informant report [AUC, 95.9%; 95% confidence intervals (CI), 95.4-96.3%] was significantly better than brief cognitive test (AUC, 93.0%; 95% CI, 92.4-93.6%) and the combined measure had the best performance (AUC, 97.0%; 95% CI, 96.7-97.4%). However, to detect both MCI and dementia, only the combined measure had excellent performance (AUC, 93.0%; 95% CI, 92.5-93.4%), whereas stand-alone informant report or brief cognitive test performed suboptimally (AUC < 90%). Performance of the three strategies was not affected by participants' age, educational attainment or underlying prevalence of MCI and dementia.

CONCLUSIONS

For case finding of dementia in ambulatory care settings, informant reports would suffice as first-line measures and brief cognitive tests may optionally be added on, in services with available resources, to further improve the accuracy of detection. For case finding of both MCI and dementia, a combination of informant reports and brief cognitive tests remains the most appropriate strategy.

Subjective cognitive decline, anxiety symptoms, and the risk of mild cognitive impairment and dementia

BACKGROUND

Subjective cognitive decline (SCD) and anxiety symptoms both predict neurocognitive disorders, but the two correlate strongly with each other. It is unclear whether they reflect two independent disease processes in the development of neurocognitive disorders and hence deserve separate attention. This cohort study examined whether SCD and anxiety symptoms demonstrate independent risks of mild cognitive disorder and dementia (MCI/dementia).

METHODS

The study included 14,066 participants aged ≥ 50 years and diagnosed with normal cognition at baseline, recruited from Alzheimer's Disease Centers across the USA. The participants were evaluated for SCD and anxiety symptoms at baseline and followed up almost annually for incident MCI/dementia (median follow-up 4.5 years; interquartile range 2.2-7.7 years). SCD and anxiety symptoms were included in Cox regression to investigate their independent risks of MCI/dementia.

RESULTS

SCD and anxiety symptoms demonstrated independent risks of MCI/dementia, with HR 1.9 (95% CI 1.7-2.1) and 1.3 (95% CI 1.2-1.5), respectively. Co-occurring SCD and anxiety symptoms demonstrated the highest risk (HR 2.4, 95% CI 1.9-2.9)-participants in this group had a 25% probability of developing MCI/dementia by 3.1 years (95% 2.4-3.7), compared to 8.2 years among those without SCD or anxiety (95% CI 7.9-8.6). The results remained robust even in the sensitivity analyses that took into account symptom severity and consistency of symptoms in the first 2 annual visits.

CONCLUSIONS

The findings suggest that clinicians should not dismiss one over the other when patients present with both SCD and anxiety and that both constructs may potentially be useful to identify high-risk populations for preventive interventions and trials. The findings also point to the need for further research to clarify on the neurobiological distinctions between SCD and anxiety symptoms, which may potentially enrich our understanding on the pathogenesis of neurocognitive disorders.

Neuropsychiatric symptoms in cognitively normal older persons, and the association with Alzheimer's and non-Alzheimer's dementia

Background

Neuropsychiatric symptoms (NPS) have been reported to be useful in predicting incident dementia among cognitively normal older persons. However, the literature has not been conclusive on the differential utilities of the various NPS in predicting the subtypes of dementia. This study compared the risks of Alzheimer’s and non-Alzheimer’s dementia associated with the various NPS, among cognitively normal older persons.

Methods

This cohort study included 12,452 participants from the Alzheimer’s Disease Centers across USA, who were ≥ 60 years and had normal cognition at baseline. Participants completed the Neuropsychiatric Inventory-Questionnaire at baseline and were followed up almost annually for incident dementia (median follow-up = 4.7 years). Symptom clusters of NPS—as identified from exploratory and confirmatory factor-analyses—were included in the Cox regression to investigate their associations with incident dementia.

Results

The various NPS showed independent yet differential associations with incident dementia. Although psychotic symptoms were rarely endorsed by the participants, they predicted much higher risk of dementia (HR 3.6, 95% CI 2.0–6.4) than affective symptoms (HR 1.5, 95% CI 1.2–1.8) or agitation symptoms (HR 1.6, 95% CI 1.3–2.1). Psychotic symptoms predicted all dementia subtypes, while affective and agitation symptoms differentially predicted some subtypes. Across dementia subtypes, psychotic symptoms had relatively higher risk estimates than affective or agitation symptoms, with the risk estimates being particularly high in non-Alzheimer’s dementia.

Conclusions

Among cognitively normal individuals, the presence of NPS may warrant greater clinical vigilance as precursors to dementia and its subtypes. The findings highlight the need for further research to enrich our understanding on the neurobiological links between various NPS and dementia subtypes. They may also change the clinical approach in managing late-life psychotic symptoms, requiring a greater emphasis on dementia surveillance in the diagnostic criteria of late-life psychotic disorders.

A 4-Item Case-Finding Tool to Detect Dementia in Older Persons

OBJECTIVES

Brief cognitive tests are recommended in clinical services outside of specialized memory clinics as case-finding tools to reduce the diagnostic gap of dementia. Although the Montreal Cognitive Assessment (MoCA) is among the most widely used brief tests in specialized memory clinics, its length precludes routine use in nonspecialty clinics. This study investigated whether a small subset of MoCA would suffice to match the performance of the full MoCA in detecting dementia and, hence, be useful in nonspecialty clinics.

DESIGN

Cross-sectional test research.

SETTING

Alzheimer's Disease Centers across the United States.

PARTICIPANTS

Participants age ≥65 years (n = 8773).

MEASURES

Participants completed MoCA and were evaluated for dementia. The study sample was split into 2: the derivation sample (n = 4386) was used to develop a short variant of MoCA that best distinguish dementia (using the best-subset-approach with 10-fold cross-validation), while the validation sample (n = 4387) verified its actual performance using area under the receiver operating characteristic-curve (AUC).

RESULTS

A 4-item cognitive test was identified, comprising Clock-drawing, Tap-at-letter-A, Orientation, and Delayed-recall. It demonstrated excellent performance in distinguishing dementia from nondementia (AUC 94.2%) and was comparable to that of MoCA (AUC 93.8%), even across education subgroups. It explained 85.9% of the variability in MoCA and had scores that could be mapped to MoCA with reasonable precision. At the optimal cut-off score of <10, it demonstrated 87.9% sensitivity and 87.6% specificity in detecting dementia.

CONCLUSIONS AND IMPLICATIONS

Using rigorous methods, this study developed a brief cognitive test that is free of charge, takes <5 minutes to complete, covers the key cognitive domains, and has standardized instructions to allow its administration even by nonphysicians. This brief test is well suited as a case-finding tool in nonspecialty clinics (such as in primary care and geriatric clinics) and may improve care-integration with specialized memory clinics that utilize MoCA.