Translating Visual Short-Term Memory Binding Tasks to Clinical Practice: From Theory to Practice

Neural deterioration and compensation in visual short-term memory among individuals with amnestic mild cognitive impairment

INTRODUCTION

Visual short-term memory (VSTM) is a critical indicator of Alzheimer's disease (AD), but whether its neural substrates could adapt to early disease progression and contribute to cognitive resilience in amnestic mild cognitive impairment (aMCI) has been unclear.

METHODS

Fifty-five aMCI patients and 68 normal controls (NC) performed a change-detection task and underwent multimodal neuroimaging scanning.

RESULTS

Among the atrophic brain regions in aMCI, VSTM performance correlated with the volume of the right prefrontal cortex (PFC) but not the medial temporal lobe (MTL), and this correlation was mainly present in patients with greater MTL atrophy. Furthermore, VSTM was primarily correlated with frontal structural connectivity in aMCI but was correlated with more distributed frontal and MTL connectivity in NC.

DISCUSSION

This study provided evidence on neural adaptation in the precursor stages of AD, highlighting the compensatory role of PFC as MTL deteriorated and suggesting potential targets in early intervention for cognitive preservation.

HIGHLIGHTS

Atrophic left medial temporal lobe (MTL) no longer correlated with visual short-term memory (VSTM) in amnestic mild cognitive impairment (aMCI). Atrophic right middle frontal area continued to correlate with VSTM in aMCI. Frontal brain-behavior correlation was mainly present in the aMCI subgroup with greater medial temporal lobe (MTL) atrophy. Reliance of VSTM on frontal connectivity increased in compensation for MTL dysfunction.

Norms for the Triana Test: A Story Recall Test Based on Emotional Material

Background

The "Triana Test" is a novel story recall test based on emotional material with demonstrated accuracy in diagnosing mild cognitive impairment patients.

Objective

This study aims to obtain normative data for the "Triana Test".

Methods

A normative study was conducted at a university hospital in Spain. Partners of patients were systematically recruited if eligible (age ≥50, no memory complaints, and a total TMA-93 score at or above the 10th percentile). The "Triana Test" was administered and scored. For developing the normative data, a regression-based method was followed.

Results

The final sample included 362 participants (median age = 66, range = 50-88; 64.9% females). A model including age and educational level better predicted the total scores. Combinations of these variables resulted in different 10th percentile scores.

Conclusions

Norms for using the "Triana Test" are now available. The provided cutoffs for the 10th percentile will aid in the diagnosis of prodromal Alzheimer's disease.

Using Cognitive Reserve to Create Norms for the TMA-93 (Relational Binding of Images)

BACKGROUND

TMA-93 examines relational binding using images. Biomarker validation has demonstrated that it is discriminative for diagnosing early AD. The effect of cognitive reserve on TMA-93 performance remains unexplored and could improve the interpretative framework for using the test.

OBJECTIVE

To study the effect of cognitive reserve on TMA-93 performance and to provide new norms for the test that include its measurement.

METHODS

Cognitively unimpaired people aged 55 and over were systematically recruited for this cross-sectional normative study in southern Spain. Age, sex, and scores on the Cognitive Reserve Questionnaire (CRQ; maximum score: 25 points) were collected, and the TMA-93 was administered (maximum score: 30 points). Percentile-based reference data that captured combinations of socio-demographics variables with significant effect on TMA-93 performance were calculated.

RESULTS

902 participants (62.5% female; age: median = 68, IQR = 61-75, range = 55-90) were included. CRQ total scores were globally low (median = 8, IQR = 5-13, range = 0-24). Cognitive reserve, including modifiable items as reading activity and intellectual gaming activity, and age mainly supported the TMA-93 total score variance. Sex seemed to have some influence in the elderly. TMA-93 total scores medians began to drop from 70-75 years old. Higher total score on the CRQ and, possibly, female sex determined a gentler slope. New norms based on these variables showed wide variations in scores for the 5th and 10th percentiles.

CONCLUSION

Visual relational binding ability depends on cognitive reserve, including modifiable items. The age-related binding deficit is buffered by higher cognitive reserve and, at older ages, by female sex.

Testing Visual Binding by the TMA-93 in People Aged 75 and Over

Background: TMA-93 examines relational binding using images. The test has been proven to be discriminative for diagnosing early Alzheimer’s disease by biomarkers. Norms for this test are available, but the elderly, at high risk for Alzheimer’s disease, have not yet been widely represented. Objective: To extend normative data on the TMA-93 for people aged 75 and over. Methods: An extension of the Spanish TMA-93 normative study was undertaken. Only cognitively unimpaired people aged 75 and over were included. Age, gender, and educational attainment were registered as socio-demographic variables. Using histograms analysis, median comparisons, and linear regression analysis, we selected variables that demonstrated influence on TMA-93 total scores and provided percentile-base reference data according to combinations of those variables. Results: We included 431 new participants, resulting in a total sample of 657 individuals (median age = 78, interquartile range = 76–81, range = 75–93). Percentile-base reference data stratified by a combination of age ranges (75–79, n = 428; and ≥80 years, n = 229), and educational attainment (<  first grade, n = 253; first grade, n = 209; >  first grade, n = 195) revealed that participants achieved a minimum TMA-93 total score of 26/30 at the 50th-percentile regardless of stratum. At the 10th-percentile, a maximum of 24/30 was achieved in the more educated stratum contrasting with a minimum of 19/30 in the less educated stratum. Conclusion: Although mitigated by lower levels of education, performance on the TMA-93 is widely preserved in cognitively unimpaired people aged 75 and over. The test could facilitate the screening of elderly patients with memory complaints.

Effects of item distinctiveness on the retrieval of objects and object-location bindings from visual working memory

Visual working memory (VWM) is prone to interference from stored items competing for its limited capacity. Distinctiveness or similarity of the items is acknowledged to affect this competition, such that poor item distinctiveness causes a failure to discriminate between items sharing common features. In three experiments, we studied how the distinctiveness of studied real-world objects (i.e., whether the objects belong to the same or different basic categories) affects the retrieval of objects themselves (simple recognition) and object-location conjunctions (information about which object was where in a display, cued recall). In Experiments 1 and 2, we found that distinctiveness did not affect memories for objects or for locations, but low-distinctive objects were more frequently reported at "swapped" locations that originally contained other objects, showing object-location memory swaps. In Experiments 3 we found that observers swapped the location of a tested object with another object from the same category more frequently than with any of the objects from another category. This suggests that more similar studied objects cause more retrieval competition in object-location judgments than in simple recognition. Additionally, we discuss a possible role of categorical labeling of locations that can support object-location retrieval when the studied objects are highly distinct.

Visual short-term memory impairments in presymptomatic familial Alzheimer's disease: A longitudinal observational study

Visual short-term memory (VSTM) deficits including VSTM binding have been associated with Alzheimer's disease (AD) from preclinical to dementia stages, cross-sectionally. Yet, longitudinal investigations are lacking. The objective of this study was to evaluate VSTM function longitudinally and in relation to expected symptom onset in a cohort of familial Alzheimer's disease. Ninety-nine individuals (23 presymptomatic; 9 symptomatic and 67 controls) were included in an extension cross-sectional study and a sub-sample of 48 (23 presymptomatic carriers, 6 symptomatic and 19 controls), attending two to five visits with a median interval of 1.3 years, included in the longitudinal study. Participants completed the “What was where?” relational binding task (which measures memory for object identification, localisation and object-location binding under different conditions of memory load and delay), neuropsychology assessments and genetic testing. Compared to controls, presymptomatic carriers within 8.5 years of estimated symptom onset showed a faster rate of decline in localisation performance in long-delay conditions (4s) and in traditional neuropsychology measures of verbal episodic memory. This study represents the first longitudinal VSTM investigation and shows that changes in memory resolution may be sensitive to tracking cognitive decline in preclinical AD at least as early as changes in the more traditional verbal episodic memory tasks.

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VSTM function was investigated in presymptomatic and symptomatic FAD carriers.

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PMCs showed faster decline in VSTM function (target localisation) than controls.

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Target localisation accuracy decreased with proximity to expected symptom onset.

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“What was where?” may be sensitive to tracking preclinical cognitive decline.

Anemia and the Risk of Cognitive Impairment: An Updated Systematic Review and Meta-Analysis

BACKGROUND

Cognitive impairment is one of the most common, burdensome, and costly disorders in the elderly worldwide. The magnitude of the association between anemia and overall cognitive impairment (OCI) has not been established.

OBJECTIVE

We aimed to update and expand previous evidence of the association between anemia and the risk of OCI.

METHODS

We conducted an updated systematic review and meta-analysis. We searched electronic databases, including EMBASE, PubMed, and Web of Science for published observational studies and clinical trials between 1 January 1990 and 1 June 2020. We excluded articles that were in the form of a review, letter to editors, short reports, and studies with less than 50 participants. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. We estimated summary risk ratios (RRs) with random effects.

RESULTS

A total of 20 studies, involving 6558 OCI patients were included. Anemia was significantly associated with an increased risk of OCI (adjusted RR (aRR) 1.39 (95% CI, 1.25-1.55; p < 0.001)). In subgroup analysis, anemia was also associated with an increased risk of all-cause dementia (adjusted RR (aRR), 1.39 (95% CI, 1.23-1.56; p < 0.001)), Alzheimer's disease [aRR, 1.59 (95% CI, 1.18-2.13; p = 0.002)], and mild cognitive impairment (aRR, 1.36 (95% CI, 1.04-1.78; p = 0.02)).

CONCLUSION

This updated meta-analysis shows that patients with anemia appear to have a nearly 1.39-fold risk of developing OCI than those without anemia. The magnitude of this risk underscores the importance of improving anemia patients' health outcomes, particularly in elderly patients.

TMA-93 Validation by Alzheimer's Disease Biomarkers: A Comparison with the Free and Cued Selective Reminding Test on a Biobank Sample

BACKGROUND

The Memory Associative Test TMA-93 examines visual relational binding, characteristically affected in early-AD stages.

OBJECTIVE

We aim to validate the TMA-93 by biomarkers determination and compare its diagnostic characteristics with the Free and Cued Selective Reminding Test (FCSRT).

METHODS

Retrospective analysis of a Biobank database. Patients' records initially consulted for memory complaints, scored MMSE≥22, had TMA-93 and FCSRT tested, and AD biomarker determination (Amyloid-PET or CSF), either positive or negative, were selected. As cutoffs, we considered the 10-percentile for TMA-93 (P10/TMA-93), and "total free recall" (TFR) 21/22, total recall (TR) 43/44, and Cued Index < 0.77 for FCSRT from previous Spanish validation and normative studies. Diagnostic utilities were calculated using ROC curves and compared by the DeLong method. We studied if one test improved the other test's prediction, following a forward stepwise logistic regression model.

RESULTS

We selected 105 records: 64 "positive" and 41 "negative" biomarkers. TMA-93 total score diagnostic utility (AUC = 0.72; 95%CI:0.62-0.82) was higher than those of the FCSRT: TFR (AUC = 0.70; 95%CI: 0.60-0.80), TR (AUC = 0.63; 95%CI:0.53-0.74), and Cued Index (AUC = 0.62; 95%CI:0.52-0.73). The P10/TMA-93 cutoff showed 86%sensitivity, similar to that of the most sensitive FCSRT cutoff (TFR21/22, 89%) and 29%specificity, lower than that of the most specific FCSRT cutoff (Cued Index < 0.77, 57%). 32.8%of the positive-biomarker group scored above CI/0.77 but below p10TMA-93. The addition of TMA-93 total score to FCSRT variables improved significantly the biomarkers results' prediction.

CONCLUSION

TMA-93 demonstrated "reasonable" diagnostic utility, similar to FCSRT, for discriminating AD biomarker groups. TMA-93 total score improved the AD biomarker result prediction when added to FCSRT variables.

Eye-tracking indices of impaired encoding of visual short-term memory in familial Alzheimer's disease

The basis of visual short-term memory (VSTM) impairments in preclinical Alzheimer's disease (AD) remains unclear. Research suggests that eye movements may serve as indirect surrogates to investigate VSTM. Yet, investigations in preclinical populations are lacking. Fifty-two individuals from a familial Alzheimer's disease (FAD) cohort (9 symptomatic carriers, 17 presymptomatic carriers and 26 controls) completed the "Object-localisation" VSTM task while an eye-tracker recorded eye movements during the stimulus presentation. VSTM function and oculomotor performance were compared between groups and their association during encoding investigated. Compared to controls, symptomatic FAD carriers showed eye movement patterns suggestive of an ineffective encoding and presymptomatic FAD carriers within 6 years of their expected age at symptom onset, were more reliant on the stimuli fixation time to achieve accuracy in the localisation of the target. Consequently, for shorter fixation times on the stimuli, presymptomatic carriers were less accurate at localising the target than controls. By contrast, the only deficits detected on behavioural VSTM function was in symptomatic individuals. Our findings provide novel evidence that encoding processes may be vulnerable and weakened in presymptomatic FAD carriers, most prominently for spatial memory, suggesting a possible explanation for the subtle VSTM impairments observed in the preclinical stages of AD.

Preliminary Validation of the Triana Test: A New Story Recall Test Based on Emotional Material

OBJECTIVE

To first validate the diagnostic accuracy of the "Triana Test," a new story recall test based on emotional material.

METHOD

A phase I study of validation. We included 55 patients with amnestic Mild Cognitive Impairment and 69 healthy controls, diagnosed according to the "Memory Associative Test of the district of Seine-Saint-Denis" (TMA-93), and matched by age, gender, and educational level. The Triana Test's diagnostic accuracy was calculated by ROC curve analysis and Spearman correlations estimated its convergent validity with a hippocampal memory test, the Free and Cued Selective Reminding Test with Immediate Recall (FCSRT+IR).

RESULTS

The "Triana Test" immediate and delayed recalls showed adequate diagnostic accuracy (AUC ≥ 0,74). The delayed free recall showed the highest diagnostic accuracy (AUC = 0.86). Correlations with the FCSRT+IR were moderate to strong.

CONCLUSIONS

The "Triana Test" demonstrated accuracy for discriminating amnestic Mild Cognitive Impairment patients from healthy controls and convergent validity with the FCSRT+IR.

Reliability and Feasibility of the Memory Associative Test TMA-93

BACKGROUND

Memory tests focused on binding may be more sensitive to diagnose Alzheimer's disease (AD) at an early phase. TMA-93 examines relational binding by images.

OBJECTIVE

Evaluate the reliability (internal consistency and inter-rater and test-retest reliability) and feasibility of the TMA-93 in a clinic setting with low-educated individuals and limited face-to-face time per patient.

METHODS

The study was undertaken in a neurology outpatient clinic of a hospital in Southern Spain. The internal consistency of the TMA-93 was estimated in 35 patients with amnestic mild cognitive impairment (aMCI) and 40 healthy controls (HCs). The inter-rater reliability (by two raters) and feasibility (by recording the percentage of participants who completed the test, and by timing the administration time) were evaluated in HCs (n = 16), aMCI patients (n = 18), and mild dementia patients (n = 15). The test-retest reliability for the TMA-93 total score was studied in 51 HCs tested by the same examiner 2-4 months apart. The internal consistency was estimated by Cronbach's alpha. The inter-rater and test-retest reliability was quantified by the intraclass correlation coefficient (ICC). The administration time was compared by diagnosis.

RESULTS

The internal consistency was "optimal" (Cronbach's alpha = 0.936). The test-retest reliability was "good" [ICC = 0.802 (CI 95%  = 0.653-0.887)]. The inter-rater reliability was "optimal" [ICC = 0.999, (CI 95%  = 0.999-1)]. All participants completed the test. The administration time ranged from less than 3 min in HCs to 6 min in aMCI patients, and 7 min in mild dementia patients.

CONCLUSION

Good feasibility and reliability support using the TMA-93 for examining visual relational binding, particularly in the context of low-educational attainment and limited time per patient.