Association of Stages of Objective Memory Impairment With Incident Symptomatic Cognitive Impairment in Cognitively Normal Individuals

BACKGROUND AND OBJECTIVES

Increasing evidence indicates that a subset of cognitively normal individuals has subtle cognitive impairment at baseline. We sought to identify them using the Stages of Objective Memory Impairment (SOMI) system. Symptomatic cognitive impairment was operationalized by a Clinical Dementia Rating (CDR) ≥0.5. We hypothesized that incident impairment would be higher for participants with subtle retrieval impairment (SOMI-1), higher still for those with moderate retrieval impairment (SOMI-2), and highest for those with storage impairment (SOMI-3/4) after adjusting for demographics and APOE ε4 status. A secondary objective was to determine whether including biomarkers of β-amyloid, tau pathology, and neurodegeneration in the models affect prediction. We hypothesized that even after adjusting for in vivo biomarkers, SOMI would remain a significant predictor of time to incident symptomatic cognitive impairment.

METHODS

Among 969 cognitively normal participants, defined by a CDR = 0, from the Knight Alzheimer Disease Research Center, SOMI stage was determined from their baseline Free and Cued Selective Reminding Test scores, 555 had CSF and structural MRI measures and comprised the biomarker subgroup, and 144 of them were amyloid positive. Cox proportional hazards models tested associations of SOMI stages at baseline and biomarkers with time to incident cognitive impairment defined as the transition to CDR ≥0.5.

RESULTS

Among all participants, the mean age was 69.35 years, 59.6% were female, and mean follow-up was 6.36 years. Participants in SOMI-1-4 had elevated hazard ratios for the transition from normal to impaired cognition in comparison with those who were SOMI-0 (no memory impairment). Individuals in SOMI-1 (mildly impaired retrieval) and SOMI-2 (moderately impaired retrieval) were at nearly double the risk of clinical progression compared with persons with no memory problems. When memory storage impairment emerges (SOMI-3/4), the hazard ratio for clinical progression increased approximately 3 times. SOMI stage remained an independent predictor of incident cognitive impairment after adjusting for all biomarkers.

DISCUSSION

SOMI predicts the transition from normal cognition to incident symptomatic cognitive impairment (CDR ≥0.5). The results support the use of SOMI to identify those cognitively normal participants most likely to develop incident cognitive impairment who can then be referred for biomarker screening.

Associations of Stages of Objective Memory Impairment with Cerebrospinal Fluid and Neuroimaging Biomarkers of Alzheimer's Disease

OBJECTIVE

To investigate cerebrospinal fluid (CSF) and neuroimaging correlates of Stages of Objective Memory Impairment (SOMI) based on Free and Cued Selective Reminding Test (FCSRT) performance, and to evaluate the effect of APOE ε4 status on this relationship.

METHODS

Data from 586 cognitively unimpaired individuals who had FCSRT, CSF, and volumetric magnetic resonance imaging (MRI) measures available was used. We compared CSF measures of β-amyloid (Aβ42/Aβ40 ratio), phosphorylated tau (p-Tau181), total tau (t-Tau), hippocampal volume, and PIB-PET mean cortical binding potential with partial volume correction (MCBP) among SOMI groups in the whole sample and in subsamples stratified by APOE ε4 status.

RESULTS

Participants had a mean age of 67.4 (SD=9.1) years, had 16.1 (SD=2.6) years of education, 57.0% were female, and 33.8% were APOE ε4 positive. In the entire sample, there was no significant difference between SOMI stages in Aβ42/Aβ40 ratio, p-Tau181, t-Tau, or PIB-PET MCBP when adjusted for age, sex, and education. However, higher SOMI stages had smaller hippocampal volume (F=3.29, p=0.020). In the stratified sample based on APOE ε4 status, in APOE ε4 positive individuals, higher SOMI stages had higher p-Tau181 (F=2.94, p=0.034) higher t-Tau (F=3.41, p=0.019), and smaller hippocampal volume (F=5.78, p<0.001). There were no significant differences in CSF or imaging biomarkers between SOMI groups in the APOE ε4 negative subsample.

CONCLUSION

Cognitively normal older individuals with higher SOMI stages have higher in-vivo tau and neurodegenerative pathology only in APOE ε4 carriers. These original results indicate the potential usefulness of the SOMI staging system in assessing of tau and neurodegenerative pathology.

Association of Alcohol Consumption with Cognition in Older Population: The A4 Study

BACKGROUND

Alcohol use disorders have been categorized as a 'strongly modifiable' risk factor for dementia.

OBJECTIVE

To investigate the cross-sectional association between alcohol consumption and cognition in older adults and if it is different across sexes or depends on amyloid-β (Aβ) accumulation in the brain.

METHODS

Cognitively unimpaired older adults (N = 4387) with objective and subjective cognitive assessments and amyloid positron emission tomography (PET) imaging were classified into four categories based on their average daily alcohol use. Multivariable linear regression was then used to test the main effects and interactions with sex and Aβ levels.

RESULTS

Individuals who reported no alcohol consumption had lower scores on the Preclinical Alzheimer Cognitive Composite (PACC) compared to those consuming one or two drinks/day. In sex-stratified analysis, the association between alcohol consumption and cognition was more prominent in females. Female participants who consumed two drinks/day had better performance on PACC and Cognitive Function Index (CFI) than those who reported no alcohol consumption. In an Aβ-stratified sample, the association between alcohol consumption and cognition was present only in the Aβ- subgroup. The interaction between Aβ status and alcohol consumption on cognition was not significant.

CONCLUSION

Low or moderate consumption of alcohol was associated with better objective cognitive performance and better subjective report of daily functioning in cognitively unimpaired individuals. The association was present only in Aβ- individuals, suggesting that the pathophysiologic mechanism underlying the effect of alcohol on cognition is independent of Aβ pathology. Further investigation is required with larger samples consuming three or more drinks/day.

Predicting Amyloid Positivity in Cognitively Unimpaired Older Adults: A Machine Learning Approach Using A4 Data

BACKGROUND AND OBJECTIVES

To develop and test the performance of the Positive Aβ Risk Score (PARS) for prediction of β-amyloid (Aβ) positivity in cognitively unimpaired individuals for use in clinical research. Detecting Aβ positivity is essential for identifying at-risk individuals who are candidates for early intervention with amyloid targeted treatments.

METHODS

We used data from 4,134 cognitively normal individuals from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) Study. The sample was divided into training and test sets. A modified version of AutoScore, a machine learning-based software tool, was used to develop a scoring system using the training set. Three risk scores were developed using candidate predictors in various combinations from the following categories: demographics (age, sex, education, race, family history, body mass index, marital status, and ethnicity), subjective measures (Alzheimer's Disease Cooperative Study Activities of Daily Living-Prevention Instrument, Geriatric Depression Scale, and Memory Complaint Questionnaire), objective measures (free recall, Mini-Mental State Examination, immediate recall, digit symbol substitution, and delayed logical memory scores), and APOE4 status. Performance of the risk scores was evaluated in the independent test set.

RESULTS

PARS model 1 included age, body mass index (BMI), and family history and had an area under the curve (AUC) of 0.60 (95% CI 0.57-0.64). PARS model 2 included free recall in addition to the PARS model 1 variables and had an AUC of 0.61 (0.58-0.64). PARS model 3, which consisted of age, BMI, and APOE4 information, had an AUC of 0.73 (0.70-0.76). PARS model 3 showed the highest, but still moderate, performance metrics in comparison with other models with sensitivity of 72.0% (67.6%-76.4%), specificity of 62.1% (58.8%-65.4%), accuracy of 65.3% (62.7%-68.0%), and positive predictive value of 48.1% (44.1%-52.1%).

DISCUSSION

PARS models are a set of simple and practical risk scores that may improve our ability to identify individuals more likely to be amyloid positive. The models can potentially be used to enrich trials and serve as a screening step in research settings. This approach can be followed by the use of additional variables for the development of improved risk scores.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in cognitively unimpaired individuals PARS models predict Aβ positivity with moderate accuracy.

Associations of Stages of Objective Memory Impairment With Amyloid PET and Structural MRI: The A4 Study

BACKGROUND AND OBJECTIVES

The goal of this work was to investigate the neuroimaging correlates of the Stages of Objective Memory Impairment (SOMI) system operationalized with the Free and Cued Selective Reminding Test (FCSRT), a widely used episodic memory measure.

METHODS

The FCSRT begins with a study phase in which items (e.g., grapes) are identified in response to unique semantic cues (e.g., fruit) that are used in the test phase to prompt recall of items not retrieved by free recall. There are 3 test trials of the 16 items (maximum 48). Data from 4,484 cognitively unimpaired participants from the Anti-Amyloid Treatment in Asymptomatic Alzheimer's (A4) study were used. All participants had amyloid PET imaging, and a subset of 1,262 β-amyloid (Aβ)-positive had structural MRIs. We compared the Aβ mean cortical standardized uptake value ratio (SUVR) and volumetric measures of hippocampus, parahippocampal gyrus, entorhinal cortex, and inferior temporal cortex between the 5 SOMI stages.

RESULTS

Participants had a mean age of 71.3 (SD 4.6) years; 40.6% were male; and 34.6% were APOE ε4 positive. Half had no memory impairment; the other half had retrieval deficits, storage limitations, or both. Analysis of covariance in the entire sample while controlling for age, sex, education, and APOE ε4 showed that individuals in higher SOMI stages had higher global amyloid SUVR (p < 0.001). Both SOMI-4 and -3 subgroups had higher amyloid SUVR than SOMI-0 and SOMI-1 subgroups. Individuals in higher SOMI stages had smaller hippocampal volume (p = 0.003), entorhinal cortex (p < 0.05), and inferior temporal lobes (p < 0.05), but there was no difference between parahippocampal gyrus volume of different SOMI stages. Pairwise comparison of SOMI subgroups showed that the SOMI-4, -3, and -2 subgroups had smaller hippocampal volume than the SOMI-0 and -1 subgroup. The SOMI-4 subgroup had significantly smaller entorhinal cortex and smaller inferior temporal lobe compared to all other groups.

DISCUSSION

Presence of Alzheimer disease pathology is closely related to memory impairment according to SOMI stages in the cognitively unimpaired sample of A4. Results from structural MRIs suggest that memory storage impairment (SOMI-3 and -4) is present when there is widespread medial temporal lobe atrophy.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov identifier: NCT02008357.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that, in normal older individuals, higher stages of memory impairment assessed with FCSRT were associated with higher amyloid imaging burden and lower volume of hippocampus, entorhinal cortex, and inferior temporal lobes.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impact of sex and APOE ε4 on the association of cognition and hippocampal volume in clinically normal, amyloid positive adults

INTRODUCTION

Cognitive decline follows pathological changes including neurodegeneration on the Alzheimer's disease continuum. However, it is unclear which cognitive domains first become affected by neurodegeneration in amyloid-positive individuals and if sex or apolipoprotein (APOE) ε4 status differences affect this relationship.

METHODS

Data from 1233 cognitively unimpaired, amyloid-positive individuals 65 to 85 years of age were studied to assess the effect of hippocampal volume (HV) on cognition and to evaluate differences due to sex and APOE ε4 status.

RESULTS

Lower HV was linked with worse performance on measures of memory (free recall, total recall, logical memory delayed recall, Mini-Mental State Examination [MMSE]), executive functioning (digit symbol substitution, DSS), and the Preclinical Alzheimer's Cognitive Composite (PACC). Among both women and APOE ε4+ individuals, all cognitive measures, except MMSE, were associated with HV. DSS and PACC had the largest effect sizes in differentiating early and intermediate stage neurodegeneration.

DISCUSSION

Despite all cognitive measures being associated with HV, cognitive tests show differences in detecting early or late signs of neurodegeneration. Differences exist in association between cognition and neurodegeneration based on sex and APOE ε4 status.

Sensitivity of the Preclinical Alzheimer's Cognitive Composite (PACC), PACC5, and Repeatable Battery for Neuropsychological Status (RBANS) to Amyloid Status in Preclinical Alzheimer's Disease -Atabecestat Phase 2b/3 EARLY Clinical Trial

BACKGROUND

Cognitive composites commonly serve as primary outcomes in Alzheimer's disease (AD) secondary prevention trials.

OBJECTIVE

To evaluate the association between amyloid (Aβ) burden level (+/-) and performance on three separate composite endpoints: Preclinical Alzheimer's Cognitive Composite (PACC), PACC+Semantic Fluency (PACC5), and Repeatable Battery for Neuropsychological Status (RBANS).

DESIGN

Screening data from the randomized, double-blind, placebo-controlled, phase 2b/3 atabecestat EARLY study in preclinical AD participants were used in this analysis.

SETTING

The EARLY study was conducted at 143 centers across 14 countries.

PARTICIPANTS

3,569 cognitively unimpaired older adults (Clinical Dementia Rating of 0; aged 60-85 years) screened for inclusion in the EARLY study with Aβ status and at least PACC or RBANS at screening were included. Participants were categorized as those with non-pathological Aβ levels (Aβ-, n=2,824) and those with pathological Aβ levels (Aβ+, n=745) based on florbetapir uptake or levels of cerebrospinal fluid Aβ1-42.

MEASUREMENTS

Analysis of Covariance models controlling for age, sex, and education were used to examine the difference in PACC, PACC5, and RBANS between Aβ groups. Nonparametric bootstrap was used to compare sensitivity of composites to differentiate between Aβ status.

RESULTS

Of 3,569 participants, 2,116 were women (59%); 3,006 were Caucasian (84%); mean (SD) age was 68.98 (5.28) years. Aβ+ participants performed worse versus Aβ- participants on all cognitive composites though the magnitude of the Aβ effect was generally small. The Aβ+/- effect size for the PACC (Cohen's d=-0.15) was significantly greater than the RBANS (d=-0.097) while the PACC5 effect size (d=-0.139) was numerically larger than the RBANS. When examining subscores from the composites, memory tests (i.e., Free and Cued Selective Reminding Test, Figure Recall) and speed of processing (i.e., Digit-Symbol/Coding on the PACC/RBANS) exhibited the largest Aβ+/- effect sizes.

CONCLUSIONS

Cross-sectional relationships between Aβ and cognition among clinically unimpaired older adults are detectable on multi-domain cognitive composites but are relatively small in magnitude. The Aβ+/- group effect was statistically larger for PACC and marginally larger for PACC5 versus RBANS. However, interpretation of composite sensitivity to Aβ status cross-sectionally cannot be generalized to sensitivity to change over time.

Neuroimaging correlates of Stages of Objective Memory Impairment (SOMI) system

INTRODUCTION

To assess the relationship between memory performance defined by the Stages of Objective Memory Impairment (SOMI) system and the Alzheimer's disease (AD) ATN (amyloid beta [A], pathologic tau [T], and neurodegeneration [N]) biomarker system.

METHODS

We used data from the Harvard Aging Brain Study cohort to estimate the level of ATN biomarkers: amyloid beta (C-Pittsburgh compound B-positron emission tomography [PET]), tau (F-18-flortaucipir [FTP] PET), and neurodegeneration (magnetic resonance imaging volumetrics). We assessed the cross-sectional relationship of SOMI classification with global amyloid levels, entorhinal and inferior temporal tau deposition, and hippocampal atrophy.

RESULTS

Participants with both memory storage and retrieval deficits (SOMI-3, -4) had smaller hippocampal volumes and higher entorhinal and inferior temporal tau burden than participants with no memory impairment (SOMI-0) or mild retrieval difficulty (SOMI-1). Amyloid burden did not differ among SOMI stages.

DISCUSSION

This pilot supports the close relationship between tau pathology and memory impairment across the AD continuum.  SOMI may be useful to determine eligibility for randomized controlled trials prior to the assessment of biomarker status.

Stages of Objective Memory Impairment Predict Alzheimer's Disease Neuropathology: Comparison with the Clinical Dementia Rating Scale-Sum of Boxes

BACKGROUND

The ultimate validation of a clinical marker for Alzheimer's disease (AD) is its association with AD neuropathology.

OBJECTIVE

To examine how well the Stages of Objective Memory Impairment (SOMI) system predicts intermediate/high AD neuropathologic change and extent of neurofibrillary tangle (NFT) pathology defined by Braak stage, in comparison to the Clinical Dementia Rating (CDR) Scale sum of boxes (CDR-SB).

METHODS

251 well-characterized participants from the Knight ADRC clinicopathologic series were classified into SOMI stage at their last assessment prior to death using the free recall and total recall scores from the picture version of the Free and Cued Selective Reminding Test with Immediate Recall (pFCSRT + IR). Logistic regression models assessed the predictive validity of SOMI and CDR-SB for intermediate/high AD neuropathologic change. Receiver operating characteristics (ROC) analysis evaluated the discriminative validity of SOMI and CDR-SB for AD pathology. Ordinal logistic regression was used to predict Braak stage using SOMI and CDR-SB in separate and joint models.

RESULTS

The diagnostic accuracy of SOMI for AD diagnosis was similar to that of the CDR-SB (AUC: 85%versus 83%). In separate models, both SOMI and CDR-SB predicted Braak stage. In a joint model SOMI remained a significant predictor of Braak stage but CDR-SB did not.

CONCLUSION

SOMI provides a neuropathologically validated staging system for episodic memory impairment in the AD continuum and should be useful in predicting tau positivity based on its association with Braak stage.

The Free and Cued Selective Reminding Test Predicts Braak Stage

Background:

The ultimate validation of a clinical marker for Alzheimer’s disease (AD) is its association with AD neuropathology.

Objective:

To identify clinical measures that predict pathology, we evaluated the relationships of the picture version of the Free and Cued Selective Reminding Test (pFCSRT + IR), the Mini-Mental State Exam (MMSE), and the Clinical Dementia Rating scale Sum of Boxes (CDR-SB) to Braak stage.

Methods:

315 cases from the clinicopathologic series at the Knight Alzheimer’s Disease Research Center were classified according to Braak stage. Boxplots of each predictor were compared to identify the earliest stage at which decline was observed and ordinal logistic regression was used to predict Braak stage.

Results:

Looking at the assessment closest to death, free recall scores were lower in individuals at Braak stage III versus Braak stages 0 and I (combined) while MMSE and CDR scores for individuals did not differ from Braak stages 0/I until Braak stage IV. The sum of free recall and total recall scores independently predicted Braak stage and had higher predictive validity than MMSE and CDR-SB in models including all three.

Conclusion:

pFCSRT + IR scores may be more sensitive to early pathological changes than either the CDR-SB or the MMSE.

Relation of Diabetes to Cognitive Function in Hispanics/Latinos of Diverse Backgrounds in the United States

Objectives:To examine the association between diabetes and cognitive function within U.S. Hispanics/Latinos of Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American background. Method: This cross-sectional study included 9,609 men and women (mean age = 56.5 years), who are members of the Hispanic Community Health Study/Study of Latinos. We classified participants as having diabetes, prediabetes, or normal glucose regulation. Participants underwent a neurocognitive battery consisting of tests of verbal fluency, delayed recall, and processing speed. Analyses were stratified by Hispanic/Latino subgroup. Results: From fully adjusted linear regression models, compared with having normal glucose regulation, having diabetes was associated with worse processing speed among Cubans (β = -1.99; 95% CI [confidence interval] = [-3.80, -0.19]) and Mexicans (β = -2.26; 95% CI = [-4.02, -0.51]). Compared with having normal glucose regulation, having prediabetes or diabetes was associated with worse delayed recall only among Mexicans (prediabetes: β = -0.34; 95% CI = [-0.63, -0.05] and diabetes: β = -0.41; 95% CI = [-0.79, -0.04]). No associations with verbal fluency. Discussion: The relationship between diabetes and cognitive function varied across Hispanic/Latino subgroup.

Cardiovascular disease risk factor burden and cognition: Implications of ethnic diversity within the Hispanic Community Health Study/Study of Latinos

OBJECTIVE

Hispanics/Latinos have some of the highest prevalence rates for cardiovascular disease risk factors, but stark differences exist by self-reported background. Cardiovascular disease risk factors negatively impact cognition in Hispanics/Latinos; less is known about these relationships by Hispanic/Latino backgrounds. We investigated cognitive associations with cardiovascular disease risk factor burden in a diverse cohort, the Hispanic Community Health Study/Study of Latinos.

METHODS

Baseline data from this observational study of cardiovascular disease and its antecedents was collected from 2008-2011. We included 7,121 participants 45-74 years old from Central American, Cuban, Dominican, Mexican, Puerto Rican, or South American backgrounds. Dichotomous indicators for hypertension, diabetes, hypercholesterolemia, obesity, and smoking were evaluated and totaled, with participants grouped by lowest (0-2), middle (3) or highest (4-5) burden. Cognitive testing included the Brief Spanish English Verbal Learning Test, letter fluency, and digit symbol substitution.

RESULTS

In separate fully-adjusted linear regression models, lower fluency and digit symbol substitution performance were restricted to the highest compared to the lowest burden group; whereas the middle burden group displayed impaired memory performance compared to the lowest burden group (p-values≤0.05). Background interacted with burden for learning and memory performance. That is, the association of burden level (i.e., lowest, middle, or highest) with cognitive performance was modified by background (e.g., Mexicans vs Cuban).

CONCLUSIONS

Hispanics/Latinos with higher levels of cardiovascular disease risk factor burden displayed lower levels of cognitive performance, with learning and memory performance modified by background.

Life's Simple 7's Cardiovascular Health Metrics are Associated with Hispanic/Latino Neurocognitive Function: HCHS/SOL Results

BACKGROUND

Hispanics/Latinos are purportedly at increased risk for neurocognitive decline and dementias. Without dementia cures, low-cost, well-tolerated public health means for mitigating neurocognitive decline are needed.

OBJECTIVE

We examined associations between neurocognition and cardiovascular health (CVH) metrics (Life's Simple 7; LS7) among diverse Hispanics/Latinos. We hypothesized that higher LS7 would be associated with healthier brain function (neurocognitive performance).

METHODS

We used baseline (2008-2011) Hispanic Community Health Study/Study of Latinos (HCHS/SOL; N = 9,623; ages 45-74 years) to examine neurocognition in relation to CVH LS7 scores.

RESULTS

In age and sex adjusted models, a one unit LS7 score increase (range = 0-14) was associated with higher neurocognitive function on the B-SEVLT sum (0.23 [p < 0.01]; range = 3-42), B-SEVLT recall (0.12 [p < 0.01]; range = 0-15), Word Fluency (phonemic; 0.46 (p < 0.01); range = 0-49), and Digit Symbol Substitution (0.49 (p < 0.01); range = 0-83) tests, respectively. Stated differently, a change from the minimum LS7 (0) to maximum LS7 (14) score corresponded to higher scores on verbal learning (4.62) and memory (2.24), verbal fluency (7.0), and psychomotor processing speed (12). In fully adjusted models the associations were attenuated, but remained statistically significant. Incremental adjustments indicated that Latino background and, to a lesser extent, education were primary contributors to the evinced attenuations.

CONCLUSIONS

We found that higher neurocognitive function was associated with better LS7 CVH metrics among middle-aged and older Hispanics/Latinos. Associations between neurocognitive function and LS7 were strongest among two at-risk groups for neurocognitive decline and dementia, women and Hispanics/Latinos with lower education. Public health efforts to reduce cardiovascular disease morbidity and mortality may have additional neurocognitive benefits among at-risk Hispanics/Latinos.

Temporal unfolding of declining episodic memory on the Free and Cued Selective Reminding Test in the predementia phase of Alzheimer's disease: Implications for clinical trials

Introduction

Free and Cued Selective Reminding Test (FCSRT) performance identifies patients with preclinical disease at elevated risk for developing Alzheimer's dementia, predicting diagnosis better than other memory tests.

Methods

Based on literature mapping FCSRT performance to clinical outcomes and biological markers, and on longitudinal preclinical data from the Baltimore Longitudinal Study of Aging, we developed the Stages of Objective Memory Impairment (SOMI) model. Five sequential stages of episodic memory decline are defined by Free Recall (FR) and Total Recall (TR) score ranges and years prior to dementia diagnosis. We sought to replicate the SOMI model using longitudinal assessments of 142 Einstein Aging Study participants who developed AD over 10 years.

Results

Time to diagnosis was at least seven years if FR was intact, at least four years if TR was intact, and two years if TR was impaired, consistent with SOMI model predictions. The SOMI identified incipient dementia with excellent sensitivity and specificity.

Discussion

The SOMI model provides an efficient approach for clinical trial cognitive screening in advance of more costly biomarker studies and ultimately in clinical practice, and provides a vocabulary for understanding AD biomarker patterns and for re-analysis of existing clinical trial data.

Neuropsychological measures that detect early impairment and decline in preclinical Alzheimer disease

Identifying which neuropsychological measures detect early cognitive changes associated with Alzheimer disease (AD), brain pathology would be helpful clinically for the diagnosis of early AD and for the design of clinical trials. We evaluated which neuropsychological measures in our cognitive battery are most strongly associated with cerebrospinal fluid (CSF) biomarkers of AD brain pathology. We studied a large cohort (n = 233) of middle-to older-aged community-dwelling individuals (mean age 61 years) who had no clinical symptoms of dementia and underwent baseline CSF collection at baseline. Participants completed a battery of 9 neuropsychological measures at baseline and then every 1 to 3 years. CSF tau/Aβ42 was associated with baseline performance on 5/9 neuropsychological measures, especially measures of episodic memory, and longitudinal performance on 7/9 neuropsychological measures, especially measures of global cognition. The free recall portion of the Free and Cued Selective Reminding Task (FCSRT-free) detected declining cognition in the high CSF tau/Aβ42 group the earliest, followed by another measure of episodic memory and a sequencing task.

Identifying memory impairment and early dementia in primary care

INTRODUCTION

This study examined the operating characteristics of two-stage case finding to identify memory impairment and very mild dementia.

METHODS

Primary care patients underwent two-stage testing and a subsequent diagnostic assessment to assess outcomes. Patients who screen positive for subjective cognitive decline on the Informant Questionnaire on Cognitive Decline in the Elderly undergo memory testing with the Free and Cued Selective Reminding Test with Immediate Recall. Outcomes were determined without access to these data. A split-half design with discovery and confirmatory samples was used.

RESULTS

One hundred seventeen of 563 (21%) patients had dementia and 68 (12%) had memory impairment but not dementia. Operating characteristics were similar in the discovery and confirmatory samples. In the pooled sample, combined, patients with memory impairment or dementia were identified with good sensitivity (72%) and high specificity (90%). Differences in ethnicity, educational level, or age (≤75, >75) did not affect classification accuracy.

DISCUSSION

Two-stage screening facilitates the efficient identification of older adults with memory impairment or dementia.

Glycemic control, cognitive function, and family support among middle-aged and older Hispanics with diabetes: The Hispanic Community Health Study/Study of Latinos

AIMS

To examine among Hispanics in the U.S., a population with increased reliance on informal healthcare support structures, (1) the association between cognitive function and control of diabetes; and (2) whether this association is modified by family support.

METHODS

The Digit Symbol Substitution Test (DSST), word fluency, and learning and delayed recall components of the Spanish English Verbal Learning Test were administered to 1794 Hispanic adults aged 45-76years with diagnosed diabetes. An executive function index and global cognitive function index (GCFI) were derived. Uncontrolled diabetes (HbA1c⩾7% [53mmol/mol]) was compared across quartiles of cognitive function using multivariable logit models with interaction terms for cognitive function and family support.

RESULTS

After adjustment, lower DSST scores were associated with uncontrolled diabetes (P=0.03). Family support modified the relationship between other measures of cognition and diabetes control (Pinteraction: 0.002, 0.09). Among individuals with low family support, as cognitive function declined, the odds of uncontrolled diabetes increased (P-trend across quartiles of the GCFI, 0.015). Among those with low family support, persons in the lowest quartile of global cognitive function were more than twice as likely to have uncontrolled diabetes as those in the highest performing quartile (OR=2.31; 95% CI: 1.17, 4.55). There was no similar effect among those with high family support.

CONCLUSIONS

Family support may buffer the negative association between low cognitive functioning and diabetes control in US Hispanics/Latinos. Educational programs targeted at family members of middle-age and older persons with diabetes regardless of neurocognitive status may help improve population-level glycemic control.

Two-stage screening for early dementia in primary care

OBJECTIVE

The objective was to compare two screening strategies for dementia in an urban primary care clinic, serving a low-education, minority community composed largely of Latino and African American patients.

METHOD

Two hundred and fifty-seven patients underwent two-stage patient-based screening (PBS) and informant-based screening (IBS) followed by a diagnostic evaluation. In the first stage, PBS included brief tests of episodic memory (Memory Impairment Screen), semantic memory (Animal Fluency), and executive function (Reciting Months Backwards). For IBS, the first stage consisted of the short Informant Questionnaire on Cognitive Decline in the Elderly, administered to a family member or friend. Patients who screened positive in the first stage of either strategy underwent testing with the picture version of the Free and Cued Selective Reminding Test with Immediate Recall to identify memory impairment. Sensitivity, specificity, and positive and negative predictive values were computed for various cutoffs of each test and combination of tests. Dementia was diagnosed using Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition (DSM-IV) criteria without access to the screening test results.

RESULTS

We identified 66 patients (25.7%) with previously undiagnosed dementia. Sensitivity was the same (77%) for both strategies but specificity was higher for IBS than for PBS (92% versus 83%). IBS's higher specificity makes it the preferred strategy if a knowledgeable informant is available.

CONCLUSION

Unrecognized dementia is common in primary care. Case-finding can be improved using either PBS or IBS two-stage screening strategies.

Conventional and robust norming in identifying preclinical dementia

OBJECTIVE

To contrast four approaches to norming two widely used memory tests in older adults for the purpose of detecting preclinical dementia.

METHOD

The study sample included participants from the Einstein Aging Study who were over age 70, were free of dementia at baseline, and were followed for at least 5 years. Norms were derived from a conventional sample (excluding individuals with dementia at baseline but not those who developed dementia during follow-up) and a robust normative sample (excluding persons with dementia at baseline as well as those who developed dementia over 5 years of follow-up). Both normative samples were examined with and without adjustment for age and education. We contrasted the picture version of the Free and Cued Selective Reminding Test with Immediate Recall (pFCSRT+IR) and the Logical Memory (LM) test for their ability to identify persons with preclinical dementia, operationally defined by the development of diagnosable dementia over 5 years of follow-up, using these four approaches to developing norms for detecting preclinical dementia.

RESULTS

Of 418 participants included in the conventional normative sample, the mean age was 78.2 years, and 59% were female. There were 78 incident cases of dementia over 5 years leaving 340 participants in the robust normative sample. Means and standard deviations were defined for both the conventional and robust normative samples, and cut-scores with and without adjustment were set at 1.5 standard deviations below the mean of each test. As predicted, in comparison with the conventional sample, the robust sample had higher cut-scores, which provided higher sensitivity for detecting preclinical dementia. This effect persisted regardless of adjustment. The pFCSRT+IR was more sensitive than LM in detecting incident dementia cases.

CONCLUSION

When using cognitive test norms to identify preclinical dementia, robust norming procedures improves detection using both the pFCSRT+IR and LM.

Are clinical diagnoses of Alzheimer's disease and other dementias affected by education and self-reported race?

A randomized controlled trial examined whether the diagnostic process for Alzheimer's disease and other dementias may be influenced by knowledge of the patient's education and/or self-reported race. Four conditions were implemented: diagnostic team knows (a) race and education, (b) education only, (c) race only, or (d) neither. Diagnosis and clinical staging was established at baseline, at Wave 2, and for a random sample of Wave 3 respondents by a consensus panel. At study end, a longitudinal, "gold standard" diagnosis was made for patients with follow-up data (71%). Group differences in Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) diagnosis were estimated using logistic regression and generalized estimating equations. Sensitivity and specificity were examined for baseline diagnosis in relation to the gold standard, longitudinal diagnosis. Despite equivalent status on all measured variables across waves, members of the "knows race only" group were less likely than those of other groups to receive a diagnosis of dementia. At final diagnosis, 19% of the "knows race only" group was diagnosed with dementia versus 38% to 40% in the other 3 conditions (p = .038). Examination of sensitivities and specificities of baseline diagnosis in relation to the gold standard diagnosis showed a nonsignificant trend for lower sensitivities in the knowing race conditions (0.3846), as contrasted with knowing education only (0.480) or neither (0.600). The finding that knowledge of race may influence the diagnostic process in some unknown way is timely, given the recent State-of-the-Science conference on Alzheimer's disease prevention, the authors of which called for information about and standardization of the diagnostic process.

Memory Impairment and Executive Dysfunction are Associated with Inadequately Controlled Diabetes in Older Adults

OBJECTIVE

To assess the cross-sectional relationship of glycemic control to memory impairment and executive dysfunction in older adults with diabetes treated at an urban primary care center.

PARTICIPANTS AND METHODS

As part of a primary care-based cognitive screening program, we identified adults age 65 or older with a diagnosis of diabetes. Glycosylated hemoglobin level (HbA1c) was used to define diabetes as controlled (HbA1c <7) or inadequately controlled(HbA1c ≥ 7). Episodic memory was measured by quartile of free recall scores on the Free and Cued Selective Reminding Test. Executive function was measured using an ordinal composite score derived from animal fluency and months backward. These were the main predictors of diabetic control.

RESULTS

The 169 participants with diabetes had a median age of 74. The sample was 38% African American and 42% Latino. One hundred four (61%) had inadequately controlled diabetes. Memory impairment and executive dysfunction were independent predictors of diabetic control after adjusting for age and education. Binary logistic regression models indicated that the odds of inadequately controlled diabetes was higher for patients in the worst quartile of memory functioning compared to patients in higher quartiles of memory functioning (odds ratio = 6.4; 95% confidence interval: 2.3, 17.6). Any level of executive dysfunction increased the odds of inadequately controlled diabetes compared to patients in the best quintile of executive functioning (odds ratio = 3.6; 95% confidence interval: 1.58, 8.35).

CONCLUSIONS

Memory impairment and executive dysfunction were associated with inadequately controlled diabetes. Though causal inferences are not robust in a cross-sectional study, we suggest that cognitive dysfunction may interfere with diabetes management and that inadequate diabetic control may contribute to cognitive dysfunction.

Very mild dementia and medical comorbidity independently predict health care use in the elderly

OBJECTIVE

To determine whether dementia status and medical burden were independent predictors of emergency department (ED) visits and hospitalizations in older patients from an urban geriatric practice participating in a primary care based cognitive screening program.

PARTICIPANTS AND METHODS

A comprehensive chart review was conducted for 300 African American and Caucasian patients, including 46 with prevalent dementia and 28 with incident dementia using the Cumulative Illness Burden Scale. Hospital-based claims data was used to retrieve ED visits and hospital admissions for 5 years following baseline assessment.

RESULTS

Patients with dementia had a 49% higher rate of ED visits (IRR = 1.49; 95% CI = 1.06, 2.09) and an 83% higher risk of death than patients without dementia (HR = 1.83; 95% CI = 3.07, 0.03). Dementia status predicted hospital admissions after adjustment for medical burden (IRR = 1.37; 95% CI = 0.99, 1.89). For each one point increase in medical burden, there was an 11% increase in ED visits (IRR = 1.11; 95% CI = 1.06, 1.16), a 13% increase in hospital admissions (IRR = 1.13; 95% CI = 1.09, 1.17), and an 11% higher risk of death (HR = 1.11; 95% CI = 1.04, 1.17). Age did not predict utilization.

CONCLUSION

Dementia status and medical burden were independent predictors of ED visits and death in patients with clinically diagnosed dementia followed from the early stage of disease.

Getting teams to talk: development and pilot implementation of a checklist to promote interprofessional communication in the OR

BACKGROUND

Pilot studies of complex interventions such as a team checklist are an essential precursor to evaluating how these interventions affect quality and safety of care. We conducted a pilot implementation of a preoperative team communication checklist. The objectives of the study were to assess the feasibility of the checklist (that is, team members' willingness and ability to incorporate it into their work processes); to describe how the checklist tool was used by operating room (OR) teams; and to describe perceived functions of the checklist discussions.

METHODS

A checklist prototype was developed and OR team members were asked to implement it before 18 surgical procedures. A research assistant was present to prompt the participants, if necessary, to initiate each checklist discussion. Trained observers recorded ethnographic field notes and 11 brief feedback interviews were conducted. Observation and interview data were analyzed for trends.

RESULTS

The checklist was implemented by the OR team in all 18 study cases. The rate of team participation was 100% (33 vascular surgery team members). The checklist discussions lasted 1-6 minutes (mean 3.5) and most commonly took place in the OR before the patient's arrival. Perceived functions of the checklist discussions included provision of detailed case related information, confirmation of details, articulation of concerns or ambiguities, team building, education, and decision making. Participants consistently valued the checklist discussions. The most significant barrier to undertaking the team checklist was variability in team members' preoperative workflow patterns, which sometimes presented a challenge to bringing the entire team together.

CONCLUSIONS

The preoperative team checklist shows promise as a feasible and efficient tool that promotes information exchange and team cohesion. Further research is needed to determine the sustainability and generalizability of the checklist intervention, to fully integrate the checklist routine into workflow patterns, and to measure its impact on patient safety.

Communication failures in the operating room: an observational classification of recurrent types and effects

BACKGROUND

Ineffective team communication is frequently at the root of medical error. The objective of this study was to describe the characteristics of communication failures in the operating room (OR) and to classify their effects. This study was part of a larger project to develop a team checklist to improve communication in the OR.

METHODS

Trained observers recorded 90 hours of observation during 48 surgical procedures. Ninety four team members participated from anesthesia (16 staff, 6 fellows, 3 residents), surgery (14 staff, 8 fellows, 13 residents, 3 clerks), and nursing (31 staff). Field notes recording procedurally relevant communication events were analysed using a framework which considered the content, audience, purpose, and occasion of a communication exchange. A communication failure was defined as an event that was flawed in one or more of these dimensions.

RESULTS

421 communication events were noted, of which 129 were categorized as communication failures. Failure types included "occasion" (45.7% of instances) where timing was poor; "content" (35.7%) where information was missing or inaccurate, "purpose" (24.0%) where issues were not resolved, and "audience" (20.9%) where key individuals were excluded. 36.4% of failures resulted in visible effects on system processes including inefficiency, team tension, resource waste, workaround, delay, patient inconvenience and procedural error.

CONCLUSION

Communication failures in the OR exhibited a common set of problems. They occurred in approximately 30% of team exchanges and a third of these resulted in effects which jeopardized patient safety by increasing cognitive load, interrupting routine, and increasing tension in the OR.

Communication failures in the operating room: an observational classification of recurrent types and effects

BACKGROUND

Ineffective team communication is frequently at the root of medical error. The objective of this study was to describe the characteristics of communication failures in the operating room (OR) and to classify their effects. This study was part of a larger project to develop a team checklist to improve communication in the OR.

METHODS

Trained observers recorded 90 hours of observation during 48 surgical procedures. Ninety four team members participated from anesthesia (16 staff, 6 fellows, 3 residents), surgery (14 staff, 8 fellows, 13 residents, 3 clerks), and nursing (31 staff). Field notes recording procedurally relevant communication events were analysed using a framework which considered the content, audience, purpose, and occasion of a communication exchange. A communication failure was defined as an event that was flawed in one or more of these dimensions.

RESULTS

421 communication events were noted, of which 129 were categorized as communication failures. Failure types included "occasion" (45.7% of instances) where timing was poor; "content" (35.7%) where information was missing or inaccurate, "purpose" (24.0%) where issues were not resolved, and "audience" (20.9%) where key individuals were excluded. 36.4% of failures resulted in visible effects on system processes including inefficiency, team tension, resource waste, workaround, delay, patient inconvenience and procedural error.

CONCLUSION

Communication failures in the OR exhibited a common set of problems. They occurred in approximately 30% of team exchanges and a third of these resulted in effects which jeopardized patient safety by increasing cognitive load, interrupting routine, and increasing tension in the OR.

Occupational exposure to methyl isobutyl ketone causes lasting impairment in working memory

The authors describe serial evaluations of a 44-year-old man who became cognitively impaired during a 6-year period of repeated exposure to high levels of methyl isobutyl ketone (MIBK). Neuropsychological tests administered six times over 10 years demonstrated a stable pattern of cognitive impairment. Dynamic imaging studies suggested persistent CNS dysfunction. The authors conclude that chronic, high-level, occupational MIBK exposure can cause a persistent cognitive syndrome best explained by impaired working memory.

The relative frequency of "dementia of unknown etiology" increases with age and is nearly 50% in nonagenarians

CONTEXT

With the recent change in pathological criteria for Alzheimer disease (AD), a group of patients has emerged who do not meet pathological criteria for any well-characterized degenerative dementias. Whether these unclassified patients have vascular dementia or some other form of dementia is not known.

OBJECTIVE

To determine the clinical characteristics, pathological substrate, and relative frequency of dementia not caused by well-characterized degenerative dementias.

DESIGN/SETTING

Clinicopathological study of a prospectively observed sample of elderly nondemented and demented subjects recruited from our urban community.

METHODS

In our series of 128 subjects with prospective neuropsychological evaluations as well as neuropathology, we identified 35 clinically nondemented subjects and 20 demented patients who did not meet pathological criteria for well-characterized degenerative dementias such as AD or dementia with Lewy bodies. The 20 demented patients were grouped together under the term dementia of unknown etiology (DUE). We compared clinical, genetic, neuropsychological, pathological, and neurochemical characteristics of the nondemented group, patients with DUE, and 28 patients with AD and no other pathological abnormality.

RESULTS

Mean age at death for patients with DUE was 89.1 +/- 5.8 years compared with 79.9 +/- 11.4 years for AD (P<.001). Patients with AD and DUE did not differ in sex, risk factors, apolipoprotein E genotype, neuropsychological features, or neurological features. Hippocampal sclerosis (in 11 patients with dementia and no controls) and leukoencephalopathy (in 7 patients with dementia and 1 control) were associated with cognitive impairment; other vascular markers were not. Dementia of unknown etiology accounted for 5% of all cases of dementia among patients dying in their 70s, 21% for patients dying in their 80s, and 48% for patients dying in their 90s.

CONCLUSIONS

A significant percentage of demented patients older than 80 years do not meet pathological criteria for AD or dementia with Lewy bodies. Hippocampal sclerosis and leukoencephalopathy are common in these patients but rare in clinically nondemented subjects.

Memory impairment on free and cued selective reminding predicts dementia

OBJECTIVE

To estimate the relative rates of dementia in initially nondemented subjects with and without memory impairment defined by baseline free recall from the Free and Cued Selective Reminding (FCSR) test.

BACKGROUND

Our approach to identifying persons at high risk for future dementia is to show the presence of memory impairment not caused by other cognitive deficits by using a memory test that controls attention and cognitive processing. When the conditions of testing are not adequately controlled, prediction is reduced because age-associated memory deficits due to other cognitive deficits are confused with dementia-associated memory deficits.

METHODS

Longitudinal evaluation of 264 initially nondemented, elderly community volunteers from the Einstein Aging Study with clinical and psychometric examinations every 12 to 18 months for up to 10 years.

MAIN OUTCOME MEASURES

Dementia was defined by an algorithmic definition that required a Blessed Information Memory and Concentration score >8 and clinical evidence of functional decline.

RESULTS

Thirty-two incident cases of dementia developed during follow-up. Survival analyses indicated that subjects with impaired free recall at baseline had dementia develop (relative risk = 75.2, 95% CI = 9.9 to 567) over 5 years of follow-up at dramatically higher rates than subjects with intact free recall after adjusting for age, gender, and education.

CONCLUSION

Poor performance on free recall from FCSR predicts future dementia. These findings support the existence of a preclinical phase of dementia characterized by memory impairment, which is present for at least 5 years before diagnosis.

Memory and mental status correlates of modified Braak staging

We assessed the relationships of performance on memory and mental status tests and neuropathologic stage of Alzheimer's disease as defined by Braak and Braak in 29 patients from a prospective clinicopathologic series. We predicted that memory changes would occur at an earlier Braak stage than mental status changes. Staging was accomplished by matching the topographic distribution of neurofibrillary lesions detected with tau immunocytochemistry to the best fitting diagram published by Braak and Braak. Higher Braak stages were associated with decrements in performance on both memory and mental status tests. As predicted, memory performance declined from stages II to III and mental status did not decline until stages III to IV. The association between memory and Braak stage was unchanged after adjusting for neocortical senile plaques, whereas adjustments for Braak stage eliminated the association between cognitive functioning and amyloid burden. We conclude that Braak staging provides a useful summary of Alzheimer's disease neuropathology, which is associated with both memory and mental status performance.